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JP6798359B2 - Laminated joint and its manufacturing method - Google Patents

Laminated joint and its manufacturing method Download PDF

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JP6798359B2
JP6798359B2 JP2017038228A JP2017038228A JP6798359B2 JP 6798359 B2 JP6798359 B2 JP 6798359B2 JP 2017038228 A JP2017038228 A JP 2017038228A JP 2017038228 A JP2017038228 A JP 2017038228A JP 6798359 B2 JP6798359 B2 JP 6798359B2
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melt
solidified
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steel plates
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JP2017221973A (en
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仁寿 ▲徳▼永
仁寿 ▲徳▼永
富士本 博紀
博紀 富士本
晃樹 阪本
晃樹 阪本
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Nippon Steel Corp
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Description

本発明は、重ね接合継手とその製造方法に関し、特に、自動車車体に用いられる高強度鋼板の重ね接合継手とその製造方法に関するものである。 The present invention relates to a lap joint and a method for manufacturing the lap joint, and more particularly to a lap joint for a high-strength steel plate used for an automobile body and a method for manufacturing the same.

近年、自動車分野では、低燃費化やCO2排出量の削減のため、車体を軽量化することや、衝突安全性の向上のため、車体部材を高強度化することが求められている。これらの要求を満たすためには、車体部材や各種部品などに高強度鋼板を使用することが有効である。 In recent years, in the automobile field, it has been required to reduce the weight of the vehicle body in order to reduce fuel consumption and CO 2 emissions, and to increase the strength of the vehicle body member in order to improve collision safety. In order to satisfy these requirements, it is effective to use high-strength steel plates for vehicle body members and various parts.

このような高強度鋼板よりなる車体の組立や部品の取付けなどの工程では、主として、抵抗発熱を利用したスポット溶接が広く普及しているが、近年、スポット溶接に替えて、一部で高パワー密度を有する光線(以下、光線とする。)による接合法を用い、点状に接合を行う技術が自動車の製造に適用されつつある。 In processes such as assembling a car body made of such high-strength steel plate and attaching parts, spot welding using resistance heat generation is widely used, but in recent years, some parts have high power instead of spot welding. A technique of spot welding using a bonding method using a light beam having a density (hereinafter referred to as a light beam) is being applied to the manufacture of automobiles.

光線による点状の接合は、スポット溶接より高速の施工が可能で、スポット溶接のように分流の影響を受けないため、接合点のピッチを短くできるというメリットがあり、多点接合による車体剛性の向上も可能である。 Point-shaped joints using light rays can be performed at a higher speed than spot welding, and unlike spot welding, they are not affected by diversion, so they have the advantage of shortening the pitch of the joint points. Improvement is also possible.

一方、光線による点状の接合継手の強度は、従来の抵抗スポット溶接と同程度、もしくは低下する傾向があり、炭素量の高い980MPa以上の高強度鋼板の場合は、継手強度のうち、十字引張強度が低下する問題があった。
接合継手の品質指標の一つである継手強度には、せん断方向に引張荷重を負荷して測定する引張せん断強さ(TSS)と、剥離方向に引張荷重を負荷して測定する十字引張強さ(CTS)がある。光線による接合継手において、特に、CTSは、従来の抵抗スポット溶接と同程度、又は、低下する傾向があり、炭素量の多い高強度鋼板の場合には、CTSが低くなることがあった。
このため、高強度鋼板に光線による接合を行った場合に、CTS等の継手強度を向上させる技術が望まれていた。
On the other hand, the strength of the point-shaped joint joint by light rays tends to be about the same as or lower than that of conventional resistance spot welding, and in the case of a high-strength steel plate having a high carbon content of 980 MPa or more, the cross tension of the joint strength There was a problem that the strength decreased.
The joint strength, which is one of the quality indexes of the joint, includes the tensile shear strength (TSS) measured by applying a tensile load in the shear direction and the cross tensile strength measured by applying a tensile load in the peeling direction. There is (CTS). In joints formed by light rays, CTS tends to be as low as or lower than that of conventional resistance spot welding, and in the case of high-strength steel sheets having a large amount of carbon, CTS may be low.
Therefore, a technique for improving the joint strength such as CTS when the high-strength steel sheet is joined by light rays has been desired.

このような状況のもと、光線による接合において、継手強度を向上させる技術として、接合部の近傍に、他の接合部を形成する技術(特許文献1参照)、閉ループ状の本ビードの内側に、本ビードを焼き戻すことを目的とした他のビードを形成する技術(特許文献2、3参照)が知られている。 Under such circumstances, as a technique for improving the joint strength in joining with a light beam, a technique for forming another joint in the vicinity of the joint (see Patent Document 1), inside the closed loop-shaped main bead. , A technique for forming another bead for the purpose of tempering the present bead (see Patent Documents 2 and 3) is known.

このようなループ状に光線による接合部を形成する技術では、接合部の接合面積が小さくなり、引張せん断強さ(TSS)が低くなることが懸念される。これに対して、ループ状の接合部より接合面積が広い、鋼板表面側から平面視したとき、外側輪郭が略円形状で、その中心まで溶融凝固している光線による接合部を鋼板に形成して、継手強度を向上させる技術が報告されている(特許文献4参照)。 In the technique of forming the joint portion by the light beam in such a loop shape, there is a concern that the joint area of the joint portion becomes small and the tensile shear strength (TSS) becomes low. On the other hand, when viewed from the surface side of the steel sheet, which has a larger joint area than the loop-shaped joint, the outer contour is substantially circular, and a joint formed by light rays that are melt-solidified to the center is formed on the steel sheet. (See Patent Document 4), a technique for improving joint strength has been reported.

特開2010−012504号公報Japanese Unexamined Patent Publication No. 2010-012504 特開2012−240086号公報Japanese Unexamined Patent Publication No. 2012-241986 国際公開第2012/050097号International Publication No. 2012/05007 特開昭60−68185号公報Japanese Unexamined Patent Publication No. 60-68185

特許文献4に開示の技術は、光線による接合部を点状としているので、引張せん断強さ(TSS)の向上に有効であるが、十字引張強さ(CTS)を更に向上させることが望まれていた。
そこで、本発明は、このような実情に鑑み、継手強度に優れ信頼性の向上した重ね接合継手を提供することを課題とする。
The technique disclosed in Patent Document 4 is effective in improving the tensile shear strength (TSS) because the joints formed by light rays are dotted, but it is desired to further improve the cross tensile strength (CTS). Was there.
Therefore, in view of such circumstances, it is an object of the present invention to provide a lap joint with excellent joint strength and improved reliability.

本発明者らは、鋼板に光線による接合を実施し、光線による点状の接合部を形成した接合継手のCTSを更に向上させるための手段について鋭意検討した。
重ね接合継手は、剥離方向に接合部に荷重が負荷されると、鋼板と溶融凝固部との溶融境界の近傍に応力が集中し破断に至り易いため、十分なCTS値を確保できないと考えられる。そこで、溶融境界近傍を熱処理することにより、その部分の靭性を向上させることを着想し、そのための熱処理箇所及び熱処理方法について種々調査した。
The present inventors have diligently studied means for further improving the CTS of a joint joint in which a steel plate is joined by a light beam and a point-shaped joint portion is formed by the light beam.
When a load is applied to the joint portion in the peeling direction, the lap joint joint is considered to be unable to secure a sufficient CTS value because stress is concentrated in the vicinity of the fusion boundary between the steel plate and the melt-solidified portion and is likely to break. .. Therefore, the idea was to improve the toughness of the portion by heat-treating the vicinity of the melting boundary, and various investigations were conducted on the heat-treated portion and the heat-treated method for that purpose.

その結果、点状の接合部の溶融凝固部の内側に光線を環状に照射して、照射部を再溶融凝固させるとともに、その際の熱によって鋼板と溶融凝固部との溶融境界付近を焼き戻すように再加熱することで、CTSが向上することを見出した。
本発明は、上記知見に基づいてなされたもので、その要旨とするところは以下の通りである。
As a result, the inside of the melt-solidified portion of the point-shaped joint is irradiated with light rays in a ring shape to re-melt and solidify the irradiated portion, and the heat at that time is used to burn back the vicinity of the molten boundary between the steel sheet and the melt-solidified portion. It was found that CTS was improved by reheating as described above.
The present invention has been made based on the above findings, and the gist thereof is as follows.

(1)重ね合わされた複数の鋼板で構成され、光線による点状の接合部を有する重ね接合継手において、
前記光線による点状の接合部は、前記重ね合わされた全ての鋼板に跨る点状の溶融凝固部を有し、
該溶融凝固部は、再溶融凝固部と、凝固再加熱部とを有し、
前記再溶融凝固部は、シリンダー状の形状を有し、前記溶融凝固部と鋼板との溶融境界の内側に該溶融境界とは重ならないように、かつ、重ね合わされた鋼板を貫通しないように位置しており、
前記凝固再加熱部は、前記再溶融凝固部の周囲に位置し、前記溶融境界を含んでおり、前記再溶融凝固部より軟化している
ことを特徴とする重ね接合継手。
(1) In a lap joint joint composed of a plurality of lapped steel plates and having point-shaped joints by light rays.
The point-shaped joint portion formed by the light beam has a point-shaped melt-solidified portion straddling all the overlapped steel plates.
The melt-solidified portion has a remelt-solidified portion and a solidified / reheated portion.
The remelted solidified portion has a cylinder-like shape, and is positioned inside the molten boundary between the melted solidified portion and the steel plate so as not to overlap the molten boundary and not to penetrate the overlapped steel plates. And
A lap joint joint characterized in that the solidification / reheating portion is located around the remelt / solidification portion, includes the fusion boundary, and is softened from the remelt / solidification portion.

(2)前記凝固再加熱部のうち、前記鋼板の合わせ面の前記溶融境界から、前記再溶融凝固部に向かって0.5mmの範囲のビッカース硬さの平均値は、Hv390以下であり、かつ、前記再溶融凝固部のビッカース硬さの平均値よりHv70以上低いことを特徴とする上記(1)に記載の重ね接合継手。 (2) Among the solidified and reheated portions, the average value of Vickers hardness in the range of 0.5 mm from the molten boundary of the mating surface of the steel sheet toward the remelted solidified portion is Hv390 or less and The lap joint according to (1) above, wherein the Vickers hardness of the remelted solidified portion is lower than the average value of Hv70 or more.

(3)前記複数の鋼板の板厚方向断面において、鋼板合わせ面と前記溶融境界の交点から前記再溶融凝固部までの最短距離が1.0〜3.0mmであることを特徴とする上記(1)又は(2)に記載の重ね接合継手。 (3) The shortest distance from the intersection of the steel plate mating surface and the fusion boundary to the remelt solidification portion in the cross section of the plurality of steel plates in the plate thickness direction is 1.0 to 3.0 mm (1). The lap joint according to 1) or (2).

(4)前記複数の鋼板が、表面処理皮膜を有する鋼板を1枚以上含むことを特徴とする上記(1)〜(3)のいずれかに記載の重ね接合継手。 (4) The lap joint according to any one of (1) to (3) above, wherein the plurality of steel plates include one or more steel plates having a surface treatment film.

(5)複数の鋼板を重ね合わせ、高パワー密度を有する光線を照射して前記複数の鋼板を接合する重ね接合継手の製造方法において、
重ね合わされた鋼板の一方の外表面の限られた領域内に高パワー密度を有する光線を照射し、前記重ね合わされた全ての鋼板に跨って溶融凝固させて、点状の溶融凝固部を有する光線による点状の接合部を形成し、
次いで、該溶融凝固部と鋼板との溶融境界の内側に、該溶融境界とは重ならないようにかつ、重ね合わされた鋼板を貫通しないように、高パワー密度を有する光線を環状に再照射し、該照射部分を再溶融凝固させてシリンダー状の再溶融凝固部を形成するとともに、該再溶融凝固部の周囲を再加熱して前記溶融境界を含む凝固再加熱部を形成し、
さらに、前記再溶融凝固部を形成する際の接合条件を調整して前記凝固再加熱部を前記再溶融凝固部より軟化させる
ことを特徴とする重ね接合継手の製造方法。
(5) In a method for manufacturing a lap joint, in which a plurality of steel plates are laminated and irradiated with a light beam having a high power density to join the plurality of steel plates.
A light beam having a high power density is irradiated into a limited area on one outer surface of one of the superposed steel sheets, and melt-solidified over all the superposed steel sheets to have a point-like melt-solidified portion. Forming a point-like joint by
Next, a light beam having a high power density is cyclically re-irradiated inside the melt boundary between the melt-solidified portion and the steel plate so as not to overlap the melt boundary and not to penetrate the overlapped steel plates. The irradiated portion is remelted and solidified to form a cylindrical remelted solidified portion, and the periphery of the remelted solidified portion is reheated to form a solidified and reheated portion including the melting boundary.
Further, a method for manufacturing a lap joint, which comprises adjusting the joining conditions when forming the remelted solidified portion to soften the solidified and reheated portion from the remelted solidified portion.

(6)前記光線の再照射は、前記複数の鋼板の板厚方向断面において、鋼板合わせ面と前記溶融境界の交点から前記再溶融凝固部までの最短距離が1.0〜3.0mmとなるように行われることを特徴とする上記(5)に記載の重ね接合継手の製造方法。 (6) In the re-irradiation of the light beam, the shortest distance from the intersection of the steel plate mating surface and the fusion boundary to the remelt solidification portion is 1.0 to 3.0 mm in the cross section of the plurality of steel plates in the plate thickness direction. The method for manufacturing a lap joint according to (5) above, wherein the lap joint is performed as described above.

(7)前記複数の鋼板に、表面処理皮膜を形成した鋼板を1枚以上用いることを特徴とする上記(5)又は(6)に記載の重ね接合継手の製造方法。 (7) The method for manufacturing a lap joint according to (5) or (6) above, wherein one or more steel plates having a surface treatment film formed on the plurality of steel plates are used.

ここで、光線による点状の接合部とは、重ね合わされた鋼板表面の一部の限られた領域内に光線を照射して点状に形成された溶融凝固部によって鋼板が相互に接合された部分をいう。 Here, the point-shaped joints formed by light rays are those in which the steel sheets are joined to each other by the melt-solidified parts formed in the form of dots by irradiating a part of the surface of the overlapped steel sheets with light rays. Refers to the part.

本発明によれば、溶融凝固部の溶融境界近傍に、靱性に優れる凝固再加熱部を設けたので、重ね接合継手の継手強度、特に、十字引張強さ(CTS)を向上させることができ、接合継手の信頼性を向上させることができる。そして、本発明の接合継手を自動車部品に適用することで、自動車部品の信頼性を向上させることができる。 According to the present invention, since the solidification / reheating portion having excellent toughness is provided near the fusion boundary of the melt solidification portion, the joint strength of the lap joint, particularly the cross tensile strength (CTS) can be improved. The reliability of the joint can be improved. Then, by applying the joint of the present invention to an automobile part, the reliability of the automobile part can be improved.

光線による点状の接合部を有する接合継手を模式的に示す図であり、(a)は接合継手の断面の構造を示し、(b)は接合継手のビッカース硬さ分布を示す。It is a figure which shows typically the joint which has the point-like joint part by a light ray, (a) shows the structure of the cross section of a joint joint, and (b) shows the Vickers hardness distribution of a joint joint. 光線による点状の接合部の内側に、環状に光線を照射した接合継手について、図1と同様に模式的に示す図である。It is a figure which shows typically the joint by irradiating the inside of the point-like joint part by a light ray in an annular shape, like FIG. 1. 光線による点状の接合部の内側に、環状に光線を照射した接合継手であって、図2と異なる例について、図2と同様に模式的に示す図である。It is a figure which shows typically the example which is different from FIG. 2 by irradiating the inside of the point-like joint part by a light ray with the light beam in an annular shape, like FIG. 本発明の接合継手の断面を説明する図である。It is a figure explaining the cross section of the joint joint of this invention. 光線による点状の接合部の形成の概要を示す斜視図であり、(a)は異なる照射直径で光線を照射する概要図を示し、(b)は集光面積を広くして光線を照射する概要図を示し、(c)は形成された光線による点状の接合部の斜視図を示す。It is a perspective view which shows the outline of the formation of the point-like joint part by a light ray, (a) shows the outline figure which irradiates a light ray with a different irradiation diameter, and (b) is irradiates a light beam with a wide condensing area. A schematic view is shown, and (c) shows a perspective view of a point-shaped joint portion formed by the formed light rays. 光線による点状の接合部の熱処理の概要を示す斜視図であり、(a)は光線を照射する概要図を示し、(b)は再溶融凝固部と凝固再加熱部とを有する光線による点状の接合部の斜視図を示す。It is a perspective view which shows the outline of the heat treatment of a point-like joint part by a light ray, (a) shows the outline figure which irradiates a light ray, (b) is a point by a light ray which has a remelt solidification part and a solidification reheating part. A perspective view of the shaped joint is shown.

まず、本発明に至った検討の経緯及び本発明の基本的構成について説明する。
光線による点状の接合部を有する重ね接合継手において、更に、継手強度を向上させることが望まれていた。重ね接合継手は、剥離方向に接合部に荷重が負荷されると、鋼板と溶融凝固部との境界(溶融境界)の近傍、特に、鋼板合わせ面と溶融境界との交点近傍に応力が集中し、破断に至り易い。
そこで、光線による点状の接合部における溶融境界近傍の応力が集中する部分に熱処理することを検討した。
First, the background of the study leading to the present invention and the basic configuration of the present invention will be described.
It has been desired to further improve the joint strength in a lap joint having a point-shaped joint formed by light rays. In a lap joint, when a load is applied to the joint in the peeling direction, stress is concentrated near the boundary between the steel plate and the melt solidification part (melt boundary), especially near the intersection between the steel sheet mating surface and the melt boundary. , Easy to break.
Therefore, it was examined to heat-treat the part where the stress is concentrated near the melting boundary in the point-shaped joint by light rays.

まず、重ね合わされた2枚の鋼板(引張強さ1500MPa級、板厚1.6mm)の一方の外表面に光線を照射して、照射部分を溶融凝固させて、直径が約6.0mmで、2枚の鋼板を重ね方向に柱状に貫通する溶融凝固部を有する光線による点状の接合部を形成した(図1(a)参照)。
次に、この溶融凝固部の鋼板との溶融境界の内側に、ビーム径0.4mmの光線を、直径3.0mmの円周に沿って一周再照射して、照射部分を再溶融凝固させて、溶融凝固部の内側にシリンダー状の再溶融凝固部を有するとともに、その周囲に、再溶融凝固部3aの熱により再加熱された凝固再加熱部3bを有する光線による点状の接合部を形成した(図2(a)参照)。
なお、再照射の際には、再溶融凝固部の内側端部が、鋼板合わせ面2cの延長線より鋼板2a側であって、鋼板合わせ面と溶融境界との交点がビッカース硬さの測定点が焼戻し温度範囲に加熱される位置になるように光線の照射条件を調整した。
そして、それぞれの光線による接合部を含む接合継手の板厚方向断面において、鋼板合わせ面近傍位置のビッカース硬さの変化を測定した。
図1、2の(b)にビッカース硬さの変化を概略図で示す。
First, the outer surface of one of the two stacked steel plates (tensile strength 1500 MPa class, plate thickness 1.6 mm) is irradiated with light rays to melt and solidify the irradiated portion, and the diameter is about 6.0 mm and 2 A point-shaped joint was formed by a light beam having a melt-solidified portion penetrating the steel plates in a columnar shape in the stacking direction (see FIG. 1 (a)).
Next, a light beam having a beam diameter of 0.4 mm is re-irradiated around the inside of the fusion boundary of the melt-solidified portion with the steel plate along the circumference of 3.0 mm in diameter to re-melt and solidify the irradiated portion. A cylindrical remelt solidification portion is provided inside the melt solidification portion, and a point-shaped joint portion formed by a light beam having a solidification reheat portion 3b reheated by the heat of the remelt solidification portion 3a is formed around the cylinder-shaped remelt solidification portion. (See FIG. 2 (a)).
At the time of re-irradiation, the inner end of the remelt solidification portion is on the steel plate 2a side from the extension line of the steel plate mating surface 2c, and the intersection of the steel plate mating surface and the melting boundary is the measurement point of Vickers hardness. The light irradiation conditions were adjusted so that the temperature was within the tempering temperature range.
Then, the change in Vickers hardness at the position near the steel plate mating surface was measured in the plate thickness direction cross section of the joint including the joint portion due to each light beam.
(B) of FIGS. 1 and 2 shows a schematic change in Vickers hardness.

ビッカース硬さは、図1、2の(a)図に示すように、点線Xの位置(板厚方向のビッカース硬さの測定位置)において、鋼板表面と平行方向に沿って測定範囲L1にわたってビッカース硬さを測定した。点線Xは、板厚方向において、鋼板2a、2bの合わせ面2cから鋼板2a側に0.1mmの位置である。また、L2は溶融凝固部内のビッカース硬さの測定範囲である。 As shown in FIGS. 1 and 2 (a), the Vickers hardness is measured over the measurement range L1 along the direction parallel to the steel plate surface at the position of the dotted line X (measurement position of Vickers hardness in the plate thickness direction). The hardness was measured. The dotted line X is a position 0.1 mm from the mating surface 2c of the steel plates 2a and 2b to the steel plate 2a side in the plate thickness direction. Further, L2 is a measurement range of Vickers hardness in the melt-solidified portion.

図1(b)に示すように、溶融凝固部3に光線を再照射する熱処理を施す前の接合継手1のビッカース硬さは、溶融凝固部3の内側(L2)において、HV460程度と硬く、ほぼ一定となっている。L2のすぐ外側の鋼板熱影響部は、A点以上の高温域まで加熱され、焼入れられるので、硬さが大きい。さらにその外側の鋼板熱影響部は、焼戻されて軟化部となっている。 As shown in FIG. 1 (b), the Vickers hardness of the joint joint 1 before the heat treatment for re-irradiating the melt-solidified portion 3 with light rays is as hard as about HV460 inside the melt-solidified portion 3 (L2). It is almost constant. Just outside of the steel plate heat affected zone of L2 it is heated to a high temperature range of not lower than 3 points A, because it is quenched, a large hardness. Further, the heat-affected zone of the steel sheet on the outer side is tempered to become a softened portion.

これに対し、溶融凝固部3の内側に環状に光線を再照射し、シリンダー形状に形成した再溶融凝固部3aの周囲に凝固再加熱部3bを有する接合継手1では、ビッカース硬さの測定点が、光線の再照射により焼戻し温度範囲に加熱されるため、ビッカース硬さは、図2(b)に示すように、溶融境界の前後の範囲が焼戻されて、溶融境界の内側0.5mmの範囲の平均硬さがHV300程度にまで低下した。 On the other hand, in the joint joint 1 having the solidification / reheating portion 3b around the remelting solidification portion 3a formed in a cylinder shape by re-irradiating the inside of the melt solidification portion 3 with a light beam in an annular shape, the Vickers hardness measurement point. However, since it is heated to the tempering temperature range by re-irradiation of light rays, the Vickers hardness is 0.5 mm inside the melting boundary because the range before and after the melting boundary is tempered as shown in FIG. 2 (b). The average hardness in the range of 1 was reduced to about HV300.

そして、両者の接合継手の十字引張強さ(CTS)を調査したところ、溶融凝固部の内側に光線を再照射して形成された凝固再加熱部を有する接合継手の方の十字引張強さが高くなることが判明した。これより、図2(a)に示す光線による点状の接合部が再溶融凝固部より軟化している凝固再加熱部を有するものは、溶融境界周囲が焼き戻されて硬さが低減し、靱性が向上することを知見した。また、鋼板の組合せを変えても、光線による点状の接合部が再溶融凝固部より軟化している凝固再加熱部を有するものでは、CTSの向上が確認された。 Then, when the cross tensile strength (CTS) of both joints was investigated, the cross tensile strength of the joint having the solidified and reheated portion formed by re-irradiating the inside of the molten solidified portion was found. It turned out to be higher. As a result, in the case where the point-shaped joint portion by the light beam shown in FIG. 2A has a solidification reheating portion softened from the remelt solidification portion, the periphery of the fusion boundary is tempered to reduce the hardness. It was found that the toughness was improved. Further, even if the combination of the steel plates was changed, the improvement of CTS was confirmed in the case where the point-shaped joint portion by the light beam had a solidification reheating portion softened from the remelt solidification portion.

本発明は、以上のような検討過程を経て上記(1)に記載の発明に至ったものであり、そのような本発明について、さらに、必要な要件や好ましい要件について順次説明する。 The present invention has led to the invention described in (1) above through the above-mentioned examination process, and necessary requirements and preferable requirements will be sequentially described for such an invention.

[接合継手]
本発明の接合継手10は、図4の断面図に示すように、複数の鋼板20a、20bを重ね合わせ、鋼板20a側から鋼板20aの限られた領域内に光線を照射し、光線による点状の接合部を形成して、複数の鋼板20a、20bを光線による重ね接合をしたものである。
[Joined joint]
As shown in the cross-sectional view of FIG. 4, the joint joint 10 of the present invention is formed by superimposing a plurality of steel plates 20a and 20b, irradiating a limited region of the steel plate 20a from the steel plate 20a side with light rays, and forming dots by the light rays. The joint portion of the above is formed, and a plurality of steel plates 20a and 20b are laminated and joined by a light beam.

<光線による点状の接合部>
光線による点状の接合部は、複数の鋼板20a、20bを重ね合わせ、光線の照射により溶融凝固した点状の溶融凝固部30を有しており、さらに、溶融凝固部30は、内部に該溶融凝固部が再溶融した再溶融凝固部30aと、再溶融凝固部によって溶融凝固部が凝固後に再加熱された凝固再加熱部30bとを有している。なお、図4では、鋼板側の熱影響部は示していない。
ここで、光線による点状の接合部とは、重ね合わされた鋼板表面の一部の限られた領域内に光線を照射して点状に形成された溶融凝固部によって鋼板が相互に接合された部分をいう。
<Point-shaped joints by light rays>
The point-shaped joint portion formed by the light beam has a point-shaped melt-solidified portion 30 in which a plurality of steel plates 20a and 20b are superposed and melt-solidified by irradiation with the light beam, and the melt-solidified portion 30 is internally said. It has a remelt solidification section 30a in which the melt solidification section is remelted, and a solidification reheating section 30b in which the melt solidification section is reheated after solidification by the remelt solidification section. Note that FIG. 4 does not show the heat-affected zone on the steel plate side.
Here, the point-shaped joints formed by light rays are those in which the steel sheets are joined to each other by the melt-solidified parts formed in the form of dots by irradiating a part of the surface of the overlapped steel sheets with light rays. Refers to the part.

(点状の溶融凝固部)
光線による点状の接合部に形成される溶融凝固部30は、重ね合わされた鋼板表面の一部の限られた領域内に光線を照射して形成された溶融凝固部である。
溶融凝固部30の幅W(光線の照射側から溶融凝固部を平面視したときの溶融凝固部の円相当径)は、継手強度等に応じて調整すればよく、特に限定されるものでないが、5〜12mmが例示される。好ましくは、6〜10mmである。
溶融凝固部30は、接合部を形成する複数の鋼板20a、20bに跨って形成されていれば、光線照射側と反対側の鋼板の外表面まで貫通していても、貫通していなくてもよい。
(Dot-shaped melt-solidified part)
The melt-solidified portion 30 formed in the point-shaped joint portion formed by the light beam is a melt-solidified portion formed by irradiating a limited region of a part of the surface of the stacked steel plates with a light beam.
The width W of the melt-solidified portion 30 (the equivalent circle diameter of the melt-solidified portion when the melt-solidified portion is viewed in a plan view from the light irradiation side) may be adjusted according to the joint strength and the like, and is not particularly limited. , 5-12 mm, for example. It is preferably 6 to 10 mm.
If the melt-solidified portion 30 is formed so as to straddle the plurality of steel plates 20a and 20b forming the joint portion, the melt-solidified portion 30 may or may not penetrate to the outer surface of the steel plate on the opposite side to the light irradiation side. Good.

ここで、点状とは、光線の照射側から溶融凝固部を平面視したとき、溶融凝固部の外周輪郭が円形状又多角形状などの限られた領域に限定されており、かつ、その領域の中心まで溶融凝固していることを意味する。円形状とは、光線の照射側から溶融凝固部を平面視したとき、溶融凝固部が円形や楕円形の場合以外に、直径の異なる半円や半楕円を組み合わせたものも含むものである。また、鋼板に光線を渦巻状に、外周側から中心側又は中心側から外周側に向かって照射して形成した溶融凝固部の形状も点状に含まれる。 Here, the point shape means that when the melt-solidified portion is viewed in a plan view from the irradiation side of a light beam, the outer peripheral contour of the melt-solidified portion is limited to a limited region such as a circular shape or a polygonal shape, and that region. It means that it is melted and solidified to the center of. The circular shape includes not only the case where the melt-solidified portion is circular or elliptical when the melt-solidified portion is viewed in a plan view from the light irradiation side, but also a combination of semicircles or semi-ellips having different diameters. In addition, the shape of the melt-solidified portion formed by irradiating the steel sheet with light rays in a spiral shape from the outer peripheral side to the center side or from the center side to the outer peripheral side is also included in a dot shape.

(再溶融凝固部)
再溶融凝固部30aは、溶融凝固部30と鋼板との溶融境界40の内側の溶融凝固部30に光線を環状の軌跡に沿って再照射し、照射部分を再溶融凝固させて得られるシリンダー状の形状を有する部分であり、溶融凝固したままの組織となっている。なお、環状とは、輪郭が円形状又多角形状を意味する。円形状とは、再溶融凝固部が円形や楕円形の場合以外に、直径の異なる半円や半楕円を組み合わせたものも含むものである。
(Remelt solidification part)
The remelt solidification portion 30a has a cylindrical shape obtained by re-irradiating the melt solidification portion 30 inside the fusion boundary 40 between the melt solidification portion 30 and the steel plate along an annular locus and remelting and solidifying the irradiated portion. It is a part having the shape of, and has a structure that remains melted and solidified. The circular shape means that the contour is circular or polygonal. The circular shape includes not only the case where the remelted solidified portion is circular or elliptical, but also a combination of semicircles or semicircles having different diameters.

再溶融凝固部30aは、溶融境界40とは重ならないように形成されており、その際、光線の照射側から溶融凝固部を平面視したとき、溶融凝固部の円相当の中心と、再溶融凝固部30aの円相当の中心とは、一致する必要はない。
また、再溶融凝固部30aは、接合継手10の板厚方向において、その重ね合わせ方向の先端部50が重ね合わされた鋼板を貫通しないように形成されている。下板の裏面まで貫通すると、接合部のひずみが大きくなり、凝固割れが発生しやすくなるので、貫通しないように形成する。
The remelting and solidifying portion 30a is formed so as not to overlap the melting boundary 40, and at that time, when the melting and solidifying portion is viewed in a plan view from the light irradiation side, the center corresponding to the circle of the melting and solidifying portion and the remelting portion are remelted. It does not have to coincide with the center of the solidified portion 30a corresponding to the circle.
Further, the remelt solidification portion 30a is formed so that the tip portion 50 in the stacking direction does not penetrate the stacked steel plates in the plate thickness direction of the joint joint 10. If it penetrates to the back surface of the lower plate, the strain of the joint becomes large and solidification cracks are likely to occur. Therefore, the joint is formed so as not to penetrate.

再溶融凝固部30aの重ね合わせ方向の先端部50の位置や再溶融凝固部30aの溶融境界40側の外側輪郭の位置は、鋼板合わせ面20c近傍の溶融凝固部を再加熱するために重要であり、後述するように、鋼板合わせ面と前記溶融境界の交点60近傍の溶融凝固部が、400℃以上Ac点温度以下の再加熱温度になるように設定される。
図2では、再溶融凝固部3a(30a)の先端部の位置が鋼板合わせ面2c(20c)の延長線より光線照射側(上方)にある場合を示したが、図3に、先端部の位置が鋼板合わせ面2cの延長線より下方にある場合を示す。
The position of the tip portion 50 in the overlapping direction of the remelt solidification portion 30a and the position of the outer contour of the remelt solidification portion 30a on the melting boundary 40 side are important for reheating the melt solidification portion near the steel sheet mating surface 20c. As will be described later, the melt-solidified portion near the intersection 60 of the steel sheet mating surface and the melting boundary is set to have a reheating temperature of 400 ° C. or higher and Ac 1- point temperature or lower.
FIG. 2 shows a case where the position of the tip portion of the remelted solidification portion 3a (30a) is on the light irradiation side (above) from the extension line of the steel sheet mating surface 2c (20c). The case where the position is below the extension line of the steel plate mating surface 2c is shown.

再溶融凝固部30aは、鋼板の重ね合わせ面20cの近傍にある溶融凝固部を再加熱すればよいため、その先端部50の位置は、鋼板合わせ面20cの延長線より光線照射側(上方)でも、下方でもどちらでも良いが、安定して効果を得るためには、先端部の位置が鋼板合わせ面20cの延長線より下方にある場合の方が望ましい。また、鋼板の3枚重ねの場合は、鋼板の合わせ面20cが2ヶ所形成される。このとき再溶融凝固部30aは、重ね合わせ面の延長線を横切らない深さでもよいが、望ましくは、1ヶ所の重ね合わせ面の延長線を横切ることが望ましく、2ヶ所の重ね合わせ面の延長線を横切ることがさらに望ましい。 Since the remelt solidification portion 30a may reheat the melt solidification portion near the overlapping surface 20c of the steel sheet, the position of the tip portion 50 is on the light irradiation side (above) from the extension line of the steel sheet bonding surface 20c. However, it may be either downward, but in order to obtain a stable effect, it is preferable that the position of the tip portion is below the extension line of the steel sheet mating surface 20c. Further, in the case of stacking three steel plates, two mating surfaces 20c of the steel plates are formed. At this time, the remelt solidification portion 30a may have a depth that does not cross the extension line of the overlapping surface, but it is desirable that the remelting solidification portion 30a crosses the extension line of the overlapping surface at one place, and the extension of the two overlapping surfaces. It is even more desirable to cross the line.

シリンダー状に形成される再溶融凝固部30aの径方向の幅Wb(光線の照射側から溶融凝固部を平面視したときの環状の再溶融凝固部の径方向の厚み)は、前記交点60近傍の溶融凝固部が、400℃以上Ac1点温度以下の再加熱温度になるために必要な熱量を与えるために、前記先端部の位置との関係で決められるが、0.3mm以上とすることが好ましい。幅Wbの上限は特に限定されないが、2.0mm以下であることが望ましい。 The radial width Wb of the remelted solidified portion 30a formed in a cylindrical shape (the radial thickness of the annular remelted solidified portion when the molten solidified portion is viewed in a plan view from the light irradiation side) is in the vicinity of the intersection 60. In order to give the amount of heat required for the melt-solidified portion of the above to reach the reheating temperature of 400 ° C. or higher and Ac1 point temperature or lower, it is determined in relation to the position of the tip portion, but it may be 0.3 mm or higher. preferable. The upper limit of the width Wb is not particularly limited, but it is preferably 2.0 mm or less.

(凝固再加熱部)
凝固再加熱部30bは、光線による点状の接合部の溶融凝固部30に光線を環状に再照射し、再溶融凝固部30aの周囲に溶融境界を含むように形成される部分であり、再溶融凝固部30aより軟化している部分を含むものである。
凝固再加熱部30bは、再溶融凝固部30aからの距離によって熱影響が異なる。再溶融凝固部30aに隣接した部位では、母材の融点以下Ac1点温度以上に再加熱されるため、焼入組織となる。それより離れると、Ac1点温度以下の再加熱温度となり、焼き戻された組織となる。
(Coagulation and reheating section)
The solidification / reheating portion 30b is a portion formed by re-irradiating the melt / solidification portion 30 of the point-shaped joint portion with light rays in a ring shape so as to include a melting boundary around the remelt / solidification portion 30a. It includes a portion softened from the melt-solidified portion 30a.
The solidification / reheating unit 30b has a different thermal effect depending on the distance from the remelting / solidifying unit 30a. At the portion adjacent to the remelting and solidifying portion 30a, the portion is reheated to a temperature equal to or higher than the melting point of the base metal at Ac1 point, resulting in a hardened structure. If it is separated from that, the reheating temperature becomes lower than the Ac1 point temperature, and the tempered structure is obtained.

重ね接合継手では、鋼板の剥離方向に荷重が負荷されると、鋼板の合わせ面近傍の溶融境界に応力が集中し、破断に至るため、少なくとも鋼板合わせ面20aと溶融境界40との交点60の周囲に位置する溶融凝固部が、400℃以上Ac点温度以下の再加熱温度となるように凝固再加熱部30bを形成して、その部分の靱性を向上させる。 In a lap joint, when a load is applied in the peeling direction of the steel sheet, stress concentrates on the molten boundary near the mating surface of the steel sheet, leading to fracture. Therefore, at least the intersection 60 between the steel sheet mating surface 20a and the molten boundary 40 The solidification / reheating portion 30b is formed so that the melt-coagulation portion located in the periphery has a reheating temperature of 400 ° C. or higher and Ac 1 point temperature or lower, and the toughness of the portion is improved.

具体的には、鋼板合わせ面20c近傍の溶融凝固部は、応力が集中し易いため、ビッカース硬さの平均値を、Hv390以下とし、また、再溶融凝固部30aのビッカース硬さの平均値よりHv70以上低くすることが好ましい。特に、CTSの向上のためには、鋼板合わせ面20cと前記溶融境界の交点60から内側に少なくとも0.5mmの範囲が400℃以上Ac1点温度以下の温度に加熱されることが望ましく、そのためには、鋼板の板厚方向断面において、鋼板合わせ面と前記溶融境界の交点60から前記再溶融凝固部までの最短距離Wcを、1.0〜3.0mmとすることが好ましい。
なお、再溶融凝固部はミクロ組織の観察により判別することができるので、Wcは光線による接合後の接合部の断面から測定することができる。
Specifically, since stress tends to concentrate in the melt-solidified portion near the steel plate mating surface 20c, the average value of the Vickers hardness is set to Hv390 or less, and the average value of the Vickers hardness of the remelt-solidified portion 30a is higher than the average value. It is preferable to lower Hv70 or more. In particular, in order to improve CTS, it is desirable that the range of at least 0.5 mm inward from the intersection 60 of the steel sheet mating surface 20c and the melting boundary is heated to a temperature of 400 ° C. or higher and Ac1 point temperature or lower. In the cross section of the steel plate in the plate thickness direction, the shortest distance Wc from the intersection 60 of the steel plate mating surface and the fusion boundary to the remelt solidification portion is preferably 1.0 to 3.0 mm.
Since the remelted solidified portion can be identified by observing the microstructure, Wc can be measured from the cross section of the joined portion after joining with light rays.

再溶融凝固部30a、及び、凝固再加熱部30bのビッカース硬さの平均値の測定では、中心軸Cを含む板厚方向の断面において、鋼板合わせ面20cと溶融境界40の交点60同士を結んだ線上を測定する。そして、溶融凝固部30の中央位置、及び、交点60近傍を含む3点以上等間隔でビッカース硬さを測定し、平均値を求める。具体的な測定条件の一例として、試験力0.3kgで、両端から0.15mmピッチで硬さを測定し、0.15mm、0.30mm、0.45mmでの硬さの平均値を求める。また、鋼板の重ね合わせ面が複数あるときは、それぞれの鋼板の合わせ面での交点同士を結んだ線上で測定する。 In the measurement of the average value of the Vickers hardness of the remelting and solidifying portion 30a and the solidifying and reheating portion 30b, the intersection points 60 of the steel plate mating surface 20c and the melting boundary 40 are connected in the cross section in the plate thickness direction including the central axis C. Measure on the parallel line. Then, the Vickers hardness is measured at three or more points including the central position of the melt-solidified portion 30 and the vicinity of the intersection 60, and the average value is obtained. As an example of specific measurement conditions, the hardness is measured at a pitch of 0.15 mm from both ends with a test force of 0.3 kg, and the average value of the hardness at 0.15 mm, 0.30 mm, and 0.45 mm is obtained. When there are a plurality of overlapping surfaces of the steel plates, the measurement is performed on the line connecting the intersections of the overlapping surfaces of the respective steel plates.

<複数の鋼板>
本発明の接合継手に用いる鋼板は、特に限定されるものでなく、用途に応じた機械特性等が得られる化学成分や組織の鋼板とすればよい。また、本発明の接合継手に炭素含有量を0.10質量%以上の高強度鋼板を適用すると、十字引張強さの向上が顕著であり、このような鋼板を対象とすることが好ましい。
<Multiple steel plates>
The steel sheet used for the joint of the present invention is not particularly limited, and may be a steel sheet having a chemical composition or structure that can obtain mechanical properties and the like according to the intended use. Further, when a high-strength steel sheet having a carbon content of 0.10% by mass or more is applied to the joint of the present invention, the cross tensile strength is remarkably improved, and such a steel sheet is preferably targeted.

鋼板の板厚は、特に限定されるものでなく、0.5〜3.2mmの範囲とすることができる。板厚が0.5mm未満であっても、接合部の継手強度の向上の効果は得られるが、継手強度は板厚に影響されるので、接合継手全体の強度向上の効果が小さくなり、接合継手の適用範囲が限定される。また、板厚が3.2mm超であっても、接合部の継手強度の向上の効果は得られるが、部材の軽量化の観点から、接合継手の適用範囲が限定される。 The thickness of the steel plate is not particularly limited and may be in the range of 0.5 to 3.2 mm. Even if the plate thickness is less than 0.5 mm, the effect of improving the joint strength of the joint can be obtained, but since the joint strength is affected by the plate thickness, the effect of improving the strength of the entire joint is reduced, and the joint is joined. The scope of application of joints is limited. Further, even if the plate thickness exceeds 3.2 mm, the effect of improving the joint strength of the joint portion can be obtained, but the applicable range of the joint joint is limited from the viewpoint of weight reduction of the member.

鋼板には、少なくとも接合箇所の両面又は片面に表面処理皮膜を形成した鋼板を1枚以上含んでいてもよい。表面処理皮膜は、めっき皮膜を含むものであり、更に、塗装皮膜等を含むものとすることができる。めっき皮膜としては、例えば、亜鉛めっき、アルミニウムめっき、亜鉛・ニッケルめっき、亜鉛・鉄めっき、亜鉛・アルミニウム・マグネシウム系めっき等であり、めっきの製造方法としては、溶融めっき、電気めっき等である。 The steel sheet may include at least one steel sheet having a surface treatment film formed on both sides or one side of the joint. The surface treatment film includes a plating film, and may further include a coating film and the like. Examples of the plating film include zinc plating, aluminum plating, zinc / nickel plating, zinc / iron plating, zinc / aluminum / magnesium-based plating, and the plating manufacturing method includes hot-dip plating and electroplating.

鋼板は、少なくとも接合継手を形成する部分が板状であればよく、全体が板でなくてもよい。例えば、断面ハット形の特定の形状にプレス成型された部材のフランジ部などを含むものである。重ね合わせる鋼板の枚数は、2枚に限らず、3枚以上としてもよい。また、各鋼板の、種類、成分組成及び板厚は、全て同じとしても、相互に異なっていてもよい。また、別々の鋼板から構成されるものに限定されず、1枚の鋼板を管状などの所定の形状に成形して、端部を重ね合わせたものの重ね接合継手であってもよい。 The steel plate may have at least a plate-like portion forming a joint, and may not be entirely a plate. For example, it includes a flange portion of a member press-molded into a specific shape having a hat-shaped cross section. The number of steel plates to be stacked is not limited to two, and may be three or more. Further, the type, composition and thickness of each steel sheet may be the same or different from each other. Further, the joint is not limited to those composed of separate steel plates, and may be a lap joint joint formed by molding one steel plate into a predetermined shape such as a tubular shape and overlapping the ends.

以下、これに限定されるものではないが、自動車での重ね接合継手の例を示す。
Aピラーの場合、270〜340MPa級の合金化溶融亜鉛めっき鋼板と、590〜1800MPa級非めっき鋼板もしくはホットスタンプ鋼板と、590〜1800MPa級非めっき鋼板もしくはホットスタンプ鋼板の3枚重ねの組み合わせでの重ね接合継手が例示される。
Hereinafter, an example of a lap joint in an automobile is shown, although not limited to this.
In the case of A-pillar, it is a combination of 270-340 MPa class alloyed hot-dip galvanized steel sheet, 590-1800 MPa class non-plated steel sheet or hot stamped steel sheet, and 590-1800 MPa class non-plated steel sheet or hot stamped steel sheet. A lap joint is exemplified.

Bピラーの場合、引張強さが270〜340MPa級の合金化溶融亜鉛めっき鋼板と、590〜1800MPa級非めっき鋼板もしくはホットスタンプ鋼板と、440〜980MPa級非めっき鋼板の3枚重ねの組み合わせでの重ね接合継手が例示される。 In the case of B-pillar, it is a combination of three layers of alloyed hot-dip galvanized steel sheet with tensile strength of 270-340 MPa class, 590-1800 MPa class non-plated steel sheet or hot stamped steel sheet, and 440-980 MPa class non-plated steel sheet. A lap joint is exemplified.

サイドシルの場合、270〜340MPa級の合金化溶融亜鉛めっき鋼板と、590〜1800MPa級合金化溶融亜鉛めっき鋼板と、590〜1800MPa級合金化溶融亜鉛めっき鋼板の3枚重ねの組み合わせでの重ね接合継手が例示される。 In the case of side sill, a lap joint joint consisting of a combination of 270-340 MPa class alloyed hot-dip galvanized steel sheet, 590-1800 MPa class alloyed hot-dip galvanized steel sheet, and 590-1800 MPa class alloyed hot-dip galvanized steel sheet. Is exemplified.

フロアメンバーの場合、270〜590MPa級の合金化溶融亜鉛めっき鋼板のフロアパネルと、440〜1800MPa級非めっき鋼板もしくは合金化溶融亜鉛めっき鋼板のフロアメンバーとの2枚重ねでの組み合わせでの重ね接合継手が例示される。 In the case of floor members, the floor panel of 270-590 MPa class alloyed hot-dip galvanized steel sheet and the floor member of 440-1800 MPa class non-plated steel sheet or alloyed hot-dip galvanized steel sheet are lap-bonded in a double-layered combination. A joint is exemplified.

[重ね接合継手の製造方法]
次に、本発明の重ね接合継手の製造方法について説明する。
まず、(a)複数の鋼板を重ね合わせ、重ね合わされた鋼板の一方の外表面の限られた領域内に光線を照射し、前記重ね合わされた全ての鋼板に跨って前記領域の中心まで溶融凝固させて、点状の溶融凝固部を有する光線による点状の接合部を形成することについて、図5を用いて説明する。
[Manufacturing method of lap joint]
Next, the method for manufacturing the lap joint of the present invention will be described.
First, (a) a plurality of steel plates are superposed, a light beam is irradiated into a limited region of one outer surface of the superposed steel plates, and the steel plates are melt-solidified to the center of the region across all the superposed steel plates. It will be described with reference to FIG. 5 that the point-shaped joint portion is formed by the light beam having the point-shaped melt-solidified portion.

図5は、限られた領域内(照射予定箇所)に光線を照射することによる点状の接合部の形成の概要を示す斜視図である。図5(a)は、異なる照射直径で光線を照射する概要を示し、図5(b)は、集光面積を広くして光線を照射する概要を示し、図5(c)は、形成された光線による点状の接合部を示す。 FIG. 5 is a perspective view showing an outline of formation of a point-shaped joint portion by irradiating a limited area (scheduled irradiation location) with light rays. FIG. 5A shows an outline of irradiating light rays with different irradiation diameters, FIG. 5B shows an outline of irradiating light rays with a wide condensing area, and FIG. 5C is formed. It shows a point-like joint due to the light beam.

図5(a)には、光線70を照射する方法の一例を示しており、異なる照射直径で光線70を照射するものである。この図には、光線70の照射予定箇所80aを点線で示しており、照射直径の異なる3つの照射予定箇所80aが示されている。 FIG. 5A shows an example of a method of irradiating the light beam 70, which irradiates the light ray 70 with different irradiation diameters. In this figure, the planned irradiation points 80a of the light beam 70 are shown by dotted lines, and three planned irradiation points 80a having different irradiation diameters are shown.

光線による点状の接合部の形成では、まず、複数の鋼板20a、20bを重ね合わせ、一方の鋼板20a側から光線70を照射して光線による接合を行う。光線70の照射では、光線70の照射側から照射予定箇所80aを平面視したとき、白抜き矢印で示すように、略円状に光線を走査する。その際に、光線70の照射を、外側の照射予定箇所80aに行い、その後、内側の照射予定箇所80aに行っても、内側の照射予定箇所80aに行い、その後、外側の照射予定箇所80aに行ってもよい。光線の走査方向は、特に限定されるものでなく、時計回り、反時計回りのいずれでもよい。 In the formation of the point-shaped joint portion by the light beam, first, a plurality of steel plates 20a and 20b are overlapped, and the light ray 70 is irradiated from one of the steel plates 20a side to perform the joint by the light beam. In the irradiation of the light beam 70, when the planned irradiation portion 80a is viewed in a plan view from the irradiation side of the light ray 70, the light ray is scanned in a substantially circular shape as shown by a white arrow. At that time, the light beam 70 is irradiated to the outer scheduled irradiation portion 80a, and then to the inner scheduled irradiation portion 80a, but also to the inner scheduled irradiation portion 80a, and then to the outer scheduled irradiation portion 80a. You may go. The scanning direction of the light beam is not particularly limited, and may be clockwise or counterclockwise.

また、光線70の照射側からの照射予定箇所80aを平面視した場合、光線70の照射予定箇所80aの外周形状を円としているが、楕円状、多角形状、直径の異なる半円や半楕円を組み合わせた形状、渦巻状の形状としてもよい。光線70の照射予定箇所80aを渦巻状の形状とした場合、光線70の照射は、渦巻状の照射予定箇所の外側の端部から、内側の端部に向かって、又は、渦巻状の照射予定箇所の内側の端部から、外側の端部に向かって、渦巻状に光線を走査して行う。渦巻の方向は、特に限定されるものでなく、時計回り、反時計回りのいずれでもよい。 Further, when the planned irradiation portion 80a from the irradiation side of the light beam 70 is viewed in a plan view, the outer peripheral shape of the planned irradiation portion 80a of the light ray 70 is a circle, but a semicircle or a semicircle having an elliptical shape, a polygonal shape, or a different diameter is used. It may be a combined shape or a spiral shape. When the planned irradiation point 80a of the light beam 70 has a spiral shape, the light beam 70 is scheduled to be irradiated from the outer end of the planned spiral irradiation point toward the inner end or in a spiral shape. The light beam is scanned in a spiral shape from the inner end of the portion toward the outer end. The direction of the spiral is not particularly limited, and may be clockwise or counterclockwise.

図5(a)では、直径の異なる3つの照射予定箇所を例示したが、光線の焦点面積や、光線による点状の接合部の接合面積に応じて、直径の異なる照射予定箇所の数を増減させることができる。 In FIG. 5A, three planned irradiation points having different diameters are illustrated, but the number of planned irradiation points having different diameters is increased or decreased depending on the focal area of the light beam and the joint area of the point-shaped joints formed by the light beam. Can be made to.

図5(b)には、光線70を照射する方法の他の例を示しており、集光面積を広くして光線70を照射するものである。この図には、光線70の照射予定箇所80bを点線で示している。そして、光線70の照射は、光線の集光面積を広くして、1回で行われる。 FIG. 5B shows another example of the method of irradiating the light beam 70, which irradiates the light beam 70 with a wide condensing area. In this figure, the planned irradiation portion 80b of the light beam 70 is shown by a dotted line. Then, the light beam 70 is irradiated at one time by widening the light collecting area.

図5(a)、図5(b)に示すように光線70を照射することで、図5(c)に示すように、光線による点状の接合部の溶融凝固部30を形成できる。 By irradiating the light beam 70 as shown in FIGS. 5 (a) and 5 (b), as shown in FIG. 5 (c), the melt-solidified portion 30 of the point-shaped joint portion by the light beam can be formed.

また、複数の鋼板に、表面処理皮膜を形成した鋼板を1枚以上用いる場合、光線70の照射を、外側の照射予定箇所80aに行い、その後、内側の照射予定箇所80aに行うことが好ましい。これにより、接合部内に欠陥を生じさせる気体となった皮膜を、溶融部の中心付近に集め、攪拌除去することが容易となる。なお、光線70の照射を、内側の照射予定箇所80aに行い、その後、外側の照射予定箇所80aに行っても、光線70の集光面積を広くして行っても、気体となった皮膜を溶融部から除去することができるため、これらの光線の照射方法を採用することを排除するものでない。 Further, when one or more steel plates having a surface treatment film formed on the plurality of steel plates are used, it is preferable that the light beam 70 is irradiated to the outer scheduled irradiation portion 80a and then to the inner scheduled irradiation portion 80a. As a result, it becomes easy to collect the film which has become a gas that causes defects in the joint portion near the center of the molten portion and remove it by stirring. Even if the light beam 70 is irradiated to the inner planned irradiation portion 80a and then to the outer scheduled irradiation portion 80a, or if the light collecting area of the light ray 70 is widened, the film that has become a gas is formed. Since it can be removed from the molten portion, it does not exclude the adoption of these light beam irradiation methods.

次に、(b)溶融凝固部と鋼板との溶融境界の内側に、該溶融境界とは重ならないようにかつ、重ね合わされた鋼板を貫通しないように、光線を環状に再照射し、該照射部分を再溶融凝固させてシリンダー状の再溶融凝固部を形成するとともに、該再溶融凝固部の周囲を再加熱(熱処理)して前記溶融境界を含む凝固再加熱部を形成し、
さらに、前記再溶融凝固部を形成する際の接合条件を調整して前記凝固再加熱部を前記再溶融凝固部より軟化させることについて説明する。
Next, (b) the inside of the melt boundary between the melt-solidified portion and the steel plate is re-irradiated in a ring shape with light rays so as not to overlap the melt boundary and not to penetrate the overlapped steel plates. The portion is remelted and solidified to form a cylindrical remelted solidified portion, and the periphery of the remelted solidified portion is reheated (heated) to form a solidified and reheated portion including the molten boundary.
Further, it will be described that the joining condition at the time of forming the remelted solidified portion is adjusted to soften the solidified reheated portion from the remelted solidified portion.

光線による点状の接合部の熱処理では、図5で示す方法等により得られた点状の接合部の溶融凝固部30の温度が所定温度以下、例えば、鋼板ではMs点−50℃(Ms点:マルテンサイト変態開始温度)以下となるまで待機し、その後に、鋼板20a側から溶融凝固部30の内側に光線70を照射して行う。内側とは、溶融凝固部30の溶融境界を除く溶融凝固部30内をいう。 In the heat treatment of the punctate joints with light rays, the temperature of the melt-solidified portion 30 of the punctate joints obtained by the method shown in FIG. 5 is equal to or lower than a predetermined temperature, for example, Ms points-50 ° C. (Ms points) for steel sheets. : Wait until the temperature becomes lower than the martensitic transformation start temperature), and then irradiate the inside of the melt-solidified portion 30 with light rays 70 from the steel plate 20a side. The inside means the inside of the melt-solidified portion 30 excluding the melt boundary of the melt-solidified portion 30.

溶融凝固部30の温度をMs点−50℃以下とすると、鋼板中に一定量以上のマルテンサイトが生成されるため、点状の接合部の溶融凝固部30を熱処理することで、このマルテンサイトが焼戻されて軟化し、継手強度が向上する。また、点状の接合部の溶融凝固部30の熱処理を開始するときの溶融凝固部30の温度は、Ms点−250℃以下とするのがさらに好ましい。Ms点−250℃で、一般の鋼板はマルテンサイト変態を終了するからである。 When the temperature of the melt-solidified portion 30 is Ms point −50 ° C. or lower, a certain amount or more of martensite is generated in the steel sheet. Therefore, by heat-treating the melt-solidified portion 30 of the point-shaped joint, the martensite is formed. Is tempered and softened, improving joint strength. Further, it is more preferable that the temperature of the melt-solidified portion 30 at the start of the heat treatment of the melt-solidified portion 30 of the point-shaped joint portion is Ms point −250 ° C. or lower. This is because a general steel sheet completes martensitic transformation at an Ms point of −250 ° C.

次に、光線による点状の接合部の熱処理における光線70の照射について、図6を用いて説明する。
図6(a)には、再溶融予定箇所に光線70を照射する方法の一例を示しており、光線70の照射予定箇所90を点線で示している。
光線70の照射では、白抜き矢印で示すように略円状に光線を走査する。その際に、光線の走査方向は、特に限定されるものでなく、時計回り、反時計回りのいずれでもよい。
Next, the irradiation of the light beam 70 in the heat treatment of the point-shaped joint portion by the light beam will be described with reference to FIG.
FIG. 6A shows an example of a method of irradiating the planned remelting portion with the light beam 70, and the planned irradiation portion 90 of the light beam 70 is shown by a dotted line.
In the irradiation of the light beam 70, the light ray is scanned in a substantially circular shape as indicated by the white arrow. At that time, the scanning direction of the light beam is not particularly limited, and may be clockwise or counterclockwise.

略円状の光線70の照射予定箇所90は、光線70の照射により形成されたシリンダー形状の再溶融凝固部30aにより、溶融境界40と鋼板合わせ面20cの交点60の周囲が焼き戻される位置に設定される。 The portion 90 to be irradiated with the substantially circular light beam 70 is located at a position where the circumference of the intersection 60 between the melting boundary 40 and the steel plate mating surface 20c is tempered by the cylinder-shaped remelt solidification portion 30a formed by the irradiation of the light beam 70. Set.

また、光線70の照射側から光線による接合部を平面視した場合、光線70の照射予定箇所90の外周形状を円としているが、溶融凝固部の外側輪郭に合わせて楕円状、多角形状、直径の異なる半円や半楕円を組み合わせた形状としてもよい。また、光線70の照射回数は、再溶融凝固部の幅Wbに応じて、1回または複数回としてもよい。 Further, when the joint portion formed by the light beam is viewed in a plan view from the irradiation side of the light beam 70, the outer peripheral shape of the planned irradiation portion 90 of the light beam 70 is a circle, but the elliptical shape, polygonal shape, and diameter are matched to the outer contour of the melt-solidified portion. The shape may be a combination of different semicircles and semi-ellipses. Further, the number of irradiations of the light beam 70 may be once or a plurality of times depending on the width Wb of the remelted solidification portion.

図6(a)に示すように光線70を照射することで、図6(b)に示すように、光線70の照射側から溶融凝固部30を平面視したとき、環状に再溶融凝固部30aが形成され、その周囲に凝固再加熱部30bが形成される。そして、その際に溶融境界を含む前記交点近傍が焼き戻され、靱性が向上する。 By irradiating the light beam 70 as shown in FIG. 6 (a), as shown in FIG. 6 (b), when the melt-solidified portion 30 is viewed in a plan view from the irradiation side of the light beam 70, the remelt-solidified portion 30a is annularly remelted and solidified. Is formed, and a solidification reheating portion 30b is formed around the solidification / reheating portion 30b. Then, at that time, the vicinity of the intersection including the melting boundary is tempered, and the toughness is improved.

また、光線による点状の接合部の形成、及び、光線による点状の接合部の溶融境界の熱処理において、光線の照射方法は、同じ照射方法でも、異なる照射方法でもよい。例えば、異なる照射直径で光線を照射して、点状の接合部を形成し、異なる照射直径で光線を照射して、点状の接合部の溶融境界を熱処理しても、集光面積を広くして光線を照射して、点状の接合部の形成し、異なる照射直径で光線を照射して、点状の接合部の溶融境界を熱処理してもよい。 Further, in the formation of the point-shaped joint portion by the light beam and the heat treatment of the molten boundary of the point-shaped joint portion by the light beam, the light beam irradiation method may be the same irradiation method or a different irradiation method. For example, even if light rays are irradiated with different irradiation diameters to form point-shaped joints, and light rays are irradiated with different irradiation diameters to heat the melting boundary of the point-shaped joints, the condensing area is widened. Then, the point-shaped joint may be formed by irradiating the light beam, and the molten boundary of the point-shaped joint may be heat-treated by irradiating the light with different irradiation diameters.

次に、光線70の照射のうち、凝固再加熱部30bの加熱温度について説明する。
光線による点状の接合部の溶融凝固部30のうち鋼板合わせ面20aと溶融境界40との交点60から、少なくとも0.5mmの範囲の領域が焼き戻されるように再加熱するとよい。
Next, the heating temperature of the solidification reheating unit 30b in the irradiation of the light beam 70 will be described.
It is preferable to reheat the region of at least 0.5 mm from the intersection 60 of the steel plate mating surface 20a and the melting boundary 40 in the melt-solidified portion 30 of the point-shaped joint portion by the light beam so as to be reheated.

交点60から0.5mm以上の範囲を焼き戻すには、この範囲の最高到達温度がAc点以下の所定の温度(例えば、400℃以上700℃以下)となる条件で、光線70を溶融凝固部30の内側に照射する。交点60近傍の温度は、鋼板表面で測定した温度を代表値として用いることができる。温度は、放射温度計や熱電対を用いて測定することができる。 In order to burn back the range of the intersection 60 to 0.5 mm or more, the light beam 70 is melt-coagulated under the condition that the maximum temperature reached in this range is a predetermined temperature of 1 Ac or less (for example, 400 ° C or more and 700 ° C or less). Irradiate the inside of the portion 30. As the temperature near the intersection 60, the temperature measured on the surface of the steel sheet can be used as a representative value. The temperature can be measured using a radiation thermometer or a thermocouple.

このような温度とするには、予め、再溶融凝固部の外側の円相当直径Wa又は形成される再溶融凝固部の幅Wbと、光線の再照射中の前記範囲の温度との関係や、光線の再照射時間と前記範囲の温度との関係等を調査しておき、再溶融凝固部の外側の円相当直径Wa、再溶融凝固部の幅Wb、光線の再照射時間等を調整することで行うことができる。また、交点60から0.5mmの範囲の領域を400℃以上700℃以下とするには、交点60から前記再溶融凝固部までの最短距離Wcが1.0〜3.0mmとなるように光線の照射を調整することが例示される。好ましくは、1.0〜2.0mmである。 In order to obtain such a temperature, the relationship between the circle-equivalent diameter Wa outside the remelting and solidifying portion or the width Wb of the formed remelting and solidifying portion and the temperature in the above range during reirradiation of light rays is determined in advance. Investigate the relationship between the re-irradiation time of the light beam and the temperature in the above range, and adjust the outer circle-equivalent diameter Wa of the remelt-solidified portion, the width Wb of the remelt-solidified portion, the re-irradiation time of the light beam, and the like. Can be done with. Further, in order to set the region in the range of the intersection 60 to 0.5 mm to 400 ° C. or higher and 700 ° C. or lower, the light beam is set so that the shortest distance Wc from the intersection 60 to the remelted solidification portion is 1.0 to 3.0 mm. It is exemplified to adjust the irradiation of. It is preferably 1.0 to 2.0 mm.

次に、光線による点状の接合部の形成、及び、光線による点状の接合部の熱処理で使用する光線について説明する。
光線による接合は、特に限定されるものでないが、リモートレーザ接合とすることが好ましい。リモートレーザ接合は、ロボットアームの先端に取り付けたガルバノミラーにより、光線を接合打点の間を高速で移動させて接合するものであり、接合の作業時間の大幅な短縮が可能になる。また、接合に用いる光線としては、例えば、CO2光線、YAG光線、ファイバー光線、DISK光線、半導体光線などの光線を用いることができる。
Next, the light rays used in the formation of the point-shaped joints by the light rays and the heat treatment of the point-shaped joints by the light rays will be described.
The bonding by light rays is not particularly limited, but a remote laser bonding is preferable. In remote laser joining, a galvano mirror attached to the tip of a robot arm moves light rays between joining points at high speed for joining, which makes it possible to significantly reduce the joining work time. Further, as the light beam used for bonding, for example, a light ray such as a CO 2 ray, a YAG ray, a fiber ray, a DISK ray, or a semiconductor ray can be used.

また、光線による接合の条件は、従来の条件を採用することができる。例えば、光線出力2〜30kW、集光面のビーム径0.1〜8.0mm、接合速度0.1〜60m/minの接合条件で行うことができる。 In addition, conventional conditions can be adopted as the conditions for joining with light rays. For example, the light output can be 2 to 30 kW, the beam diameter of the condensing surface is 0.1 to 8.0 mm, and the bonding speed is 0.1 to 60 m / min.

また、自動車の組み立ては、複数の接合工程からなるが、1つの工程内で本発明の製法を実施する場合、1つ1つの接合点に対して、光線照射による接合と再溶融を実施してもよいが、接合後から再溶融開始までの冷却の待ち時間を低減するため、より好適には、光線照射により複数の溶融接合を実施し、その後、光線照射により複数の再溶融を実施するとことが好ましい。また複数の接合工程で本発明の製法を実施する場合、光線照射による溶融接合工程と、光線照射による再溶融工程を別々の工程とすることで、冷却の待ち時間を無くすことができる。 Further, assembling an automobile consists of a plurality of joining steps, but when the manufacturing method of the present invention is carried out in one step, joining and remelting by light beam irradiation are carried out at each joining point. However, in order to reduce the waiting time for cooling from the joining to the start of remelting, more preferably, a plurality of melt joinings are carried out by light beam irradiation, and then a plurality of remelting is carried out by light beam irradiation. Is preferable. Further, when the manufacturing method of the present invention is carried out in a plurality of joining steps, the waiting time for cooling can be eliminated by setting the melt joining step by light irradiation and the remelting step by light irradiation as separate steps.

次に、本発明の実施例について説明する。実施例での条件は、本発明の実施可能性及び効果を確認するために採用した一条件例であり、本発明は、この一条件例に限定されるものではない。 Next, examples of the present invention will be described. The conditions in the examples are one condition example adopted for confirming the feasibility and effect of the present invention, and the present invention is not limited to this one condition example.

表1に示す鋼板を2枚重ね合わせて、ガルバノミラーを有するリモート接合装置を用い、光線にファイバーレーザを用いて接合を行い、光線による点状の接合部を有する試験片を作成した。表2に、光線による点状の接合部の形成条件を示す。ビーム径は、集光面での光線の直径である。 Two steel plates shown in Table 1 were superposed and joined by using a remote joining device having a galvanometer mirror and using a fiber laser for light rays to prepare a test piece having a point-shaped joint portion by light rays. Table 2 shows the conditions for forming point-shaped joints by light rays. The beam diameter is the diameter of the light beam on the condensing surface.

Figure 0006798359
Figure 0006798359

Figure 0006798359
Figure 0006798359

次に、各試験片に対して、鋼板合わせ面20a近傍の溶融凝固部の熱処理を行った。この熱処理では、溶融凝固部とシリンダー形状の再溶融凝固部の中心が一致するようにし、鋼板合わせ面の下側位置(0.4mm)に下端が位置するように再溶融凝固部を形成して行った。
表3に、再溶融凝固部の形成条件(熱処理条件)を示す。ビーム径は、集光面での光線の直径である。なお、熱処理では、点状の溶融凝固部の形成と同じリモート接合装置を用いた。
Next, each test piece was heat-treated in the melt-solidified portion near the steel sheet mating surface 20a. In this heat treatment, the center of the melt-solidified portion and the cylinder-shaped remelt-solidified portion are aligned, and the remelt-solidified portion is formed so that the lower end is located at the lower position (0.4 mm) of the steel plate mating surface. went.
Table 3 shows the conditions for forming the remelted solidified portion (heat treatment conditions). The beam diameter is the diameter of the light beam on the condensing surface. In the heat treatment, the same remote joining device as for forming the point-shaped melt-solidified portion was used.

Figure 0006798359
Figure 0006798359

表4に、熱処理後の試験片について、鋼板合わせ面と溶融境界の交点から前記再溶融凝固部までの最短距離Wc、再溶融凝固部の平均ビッカース硬さA、交点から0.5mmの範囲の溶融凝固部における平均ビッカース硬さB、平均ビッカース硬さAとBの差、十字引張強さ(CTS)について示す。
CTSは、JIS Z3137にスポット接合の強度試験方法として記載されている方法を援用した。
Table 4 shows the test pieces after heat treatment in the range of the shortest distance Wc from the intersection of the steel plate mating surface and the fusion boundary to the remelt solidification portion, the average Vickers hardness A of the remelt solidification portion, and 0.5 mm from the intersection. The average Vickers hardness B, the difference between the average Vickers hardnesses A and B, and the cross tensile strength (CTS) in the melt-solidified portion are shown.
For CTS, the method described in JIS Z3137 as a method for testing the strength of spot bonding was used.

Figure 0006798359
Figure 0006798359

No.2〜4、6〜8、10〜13は、光線による点状の接合部に熱処理を行い、本発明の接合継手で規定する構成をすべて満足するため、溶融凝固部の交点から0.5mmの範囲の靱性が向上し、十字引張強さ(CTS)が高くなっている。 No. In 2-4, 6-8, 10 to 13, the point-shaped joints are heat-treated by light rays, and 0.5 mm from the intersection of the melt-solidified parts in order to satisfy all the configurations specified by the joints of the present invention. The toughness of the range is improved and the cross tensile strength (CTS) is increased.

これに対して、No.1、No.5、及び、No.14は、光線による点状の接合部に熱処理を行っていないため、溶融凝固部の溶融境界の靱性が向上せず、十字引張強さ(CTS)が低くなっていた。また、No.9は、溶融凝固部の全部に熱処理を行ったため、溶融凝固部の溶融境界の靱性が向上せず、十字引張強さ(CTS)が低くなっていた。 On the other hand, No. 1, No. 5 and No. In No. 14, since the point-shaped joint portion by the light beam was not heat-treated, the toughness of the melt boundary of the melt-solidified portion was not improved, and the cross tensile strength (CTS) was low. In addition, No. In No. 9, since the entire melt-solidified portion was heat-treated, the toughness of the melt boundary of the melt-solidified portion was not improved, and the cross tensile strength (CTS) was low.

本発明によれば、光線による点状の接合部の溶融境界近傍に、靱性に優れる凝固再加熱部を設けたので、重ね接合継手の継手強度、特に、十字引張強さ(CTS)を向上させることができる。そして、本発明の接合継手を自動車部品に適用することで、自動車部品の信頼性を向上させることができる。よって、本発明は、産業上の利用可能性が高いものである。 According to the present invention, since the solidification and reheating portion having excellent toughness is provided near the melting boundary of the point-shaped joint portion by the light beam, the joint strength of the lap joint, particularly the cross tensile strength (CTS) is improved. be able to. Then, by applying the joint of the present invention to an automobile part, the reliability of the automobile part can be improved. Therefore, the present invention has high industrial applicability.

1、10 接合継手
2a、20a 鋼板
2b、20b 鋼板
2c、20c 鋼板合わせ面
3、30 光線による点状の接合部の溶融凝固部
3a、30a 溶融凝固部内に形成された再溶融凝固部
3b、30b 溶融凝固部内に形成された凝固再加熱部
40 鋼板と溶融凝固部の間の溶融境界
50 再溶融凝固部の重ね合わせ方向の先端部
60 鋼板合わせ面と溶融境界の交点
70 光線
80a、80b 照射予定箇所
90a、90b 照射予定箇所
X 板厚方向のビッカース硬さの測定位置
L1 鋼板表面と平行方向のビッカース硬さの測定範囲
L2 L1中の溶融凝固部の範囲
C 中心軸
W 溶融凝固部の円相当直径
Wa 再溶融凝固部の外側の円相当直径
Wb 再溶融凝固部の径方向の幅
Wc 鋼板合わせ面と溶融境界の交点から再溶融凝固部までの最短距離
1, 10 Joined joints 2a, 20a Steel plates 2b, 20b Steel plates 2c, 20c Steel plate mating surfaces 3, 30 Remelting and solidifying parts 3a, 30a formed in the melting and solidifying parts of point-shaped joints by light rays 3b, 30b Solidification reheating part formed in the melt solidification part 40 Melting boundary between the steel plate and the melt solidification part 50 Tip part in the overlapping direction of the remelt solidification part 60 Intersection between the steel plate mating surface and the fusion boundary 70 Rays 80a, 80b Scheduled to be irradiated Locations 90a, 90b Scheduled irradiation location X Vickers hardness measurement position in the plate thickness direction L1 Vickers hardness measurement range in the direction parallel to the steel plate surface L2 Range of melt-solidified part in L1 C Central axis W Corresponding to the circle of melt-solidified part Diameter Wa Corresponding circle diameter on the outside of the remelt solidification part Wb Radial width of the remelt solidification part Wc The shortest distance from the intersection of the steel plate mating surface and the fusion boundary to the remelt solidification part

Claims (7)

重ね合わされた複数の鋼板で構成され、光線による点状の接合部を有する重ね接合継手において、
前記光線による点状の接合部は、前記重ね合わされた全ての鋼板に跨る点状の溶融凝固部を有し、
該溶融凝固部は、再溶融凝固部と、凝固再加熱部とを有し、
前記再溶融凝固部は、シリンダー状の形状を有し、前記溶融凝固部と鋼板との溶融境界の内側に該溶融境界とは重ならないように、かつ、重ね合わされた鋼板を貫通しないように位置しており、
前記凝固再加熱部は、前記再溶融凝固部の周囲に位置し、前記溶融境界を含んでおり、前記再溶融凝固部より軟化している
ことを特徴とする重ね接合継手。
In a lap joint that is composed of a plurality of lapped steel plates and has point-like joints by light rays.
The point-shaped joint portion formed by the light beam has a point-shaped melt-solidified portion straddling all the overlapped steel plates.
The melt-coagulation section has a remelt-coagulation section and a coagulation / reheating section.
The remelted solidified portion has a cylinder-like shape, and is positioned inside the molten boundary between the melted solidified portion and the steel plate so as not to overlap the molten boundary and not to penetrate the overlapped steel plates. And
A lap joint joint characterized in that the solidification / reheating portion is located around the remelt / solidification portion, includes the fusion boundary, and is softened from the remelt / solidification portion.
前記凝固再加熱部のうち、前記鋼板の合わせ面の前記溶融境界から、前記再溶融凝固部に向かって0.5mmの範囲のビッカース硬さの平均値は、Hv390以下であり、かつ、前記再溶融凝固部のビッカース硬さの平均値よりHv70以上低いことを特徴とする請求項1に記載の重ね接合継手。 Among the solidified and reheated portions, the average value of Vickers hardness in the range of 0.5 mm from the molten boundary of the mating surface of the steel sheet toward the remelted solidified portion is Hv390 or less, and the reheating The lap joint according to claim 1, wherein the Vickers hardness of the melt-solidified portion is lower than the average value of Hv70 or more. 前記複数の鋼板の板厚方向断面において、鋼板合わせ面と前記溶融境界の交点から前記再溶融凝固部までの最短距離が1.0〜3.0mmであることを特徴とする請求項1又は2に記載の重ね接合継手。 Claim 1 or 2 is characterized in that the shortest distance from the intersection of the steel plate mating surface and the melting boundary to the remelted solidified portion is 1.0 to 3.0 mm in the cross section of the plurality of steel plates in the plate thickness direction. Laminated joints described in. 前記複数の鋼板が、表面処理皮膜を有する鋼板を1枚以上含むことを特徴とする請求項1〜3のいずれか1項に記載の重ね接合継手。 The lap joint according to any one of claims 1 to 3, wherein the plurality of steel plates include one or more steel plates having a surface treatment film. 複数の鋼板を重ね合わせ、高パワー密度を有する光線を照射して前記複数の鋼板を接合する重ね接合継手の製造方法において、
重ね合わされた鋼板の一方の外表面の限られた領域内に高パワー密度を有する光線を照射し、前記重ね合わされた全ての鋼板に跨って溶融凝固させて点状の溶融凝固部を有する光線による点状の接合部を形成し、
次いで、該溶融凝固部と鋼板との溶融境界の内側に、該溶融境界とは重ならないようにかつ、重ね合わされた鋼板を貫通しないように、高パワー密度を有する光線を環状に再照射し、該照射部分を再溶融凝固させてシリンダー状の再溶融凝固部を形成するとともに、該再溶融凝固部の周囲を再加熱して前記溶融境界を含む凝固再加熱部を形成し、
さらに、前記再溶融凝固部を形成する際の接合条件を調整して前記凝固再加熱部を前記再溶融凝固部より軟化させる
ことを特徴とする重ね接合継手の製造方法。
In a method for manufacturing a lap joint joint in which a plurality of steel plates are laminated and irradiated with a light beam having a high power density to join the plurality of steel plates.
A light beam having a high power density is irradiated into a limited area on one outer surface of one of the superposed steel sheets, and the light beam is melt-solidified across all the superposed steel sheets to have a punctate melt-solidified portion. Form a dotted joint and
Next, a light beam having a high power density is cyclically re-irradiated inside the melt boundary between the melt-solidified portion and the steel plate so as not to overlap the melt boundary and not to penetrate the overlapped steel plates. The irradiated portion is remelted and solidified to form a cylindrical remelted solidified portion, and the periphery of the remelted solidified portion is reheated to form a solidified and reheated portion including the melting boundary.
Further, a method for manufacturing a lap joint, which comprises adjusting the joining conditions when forming the remelted solidified portion to soften the solidified and reheated portion from the remelted solidified portion.
前記光線の再照射は、前記複数の鋼板の板厚方向断面において、鋼板合わせ面と前記溶融境界の交点から前記再溶融凝固部までの最短距離が1.0〜3.0mmとなるように行われることを特徴とする請求項5に記載の重ね接合継手の製造方法。 The re-irradiation of the light beam is performed so that the shortest distance from the intersection of the steel plate mating surface and the fusion boundary to the remelt solidification portion is 1.0 to 3.0 mm in the cross section of the plurality of steel plates in the plate thickness direction. The method for manufacturing a lap joint according to claim 5, wherein the lap joint is made. 前記複数の鋼板に、表面処理皮膜を形成した鋼板を1枚以上用いることを特徴とする請求項5又は6に記載の重ね接合継手の製造方法。 The method for manufacturing a lap joint according to claim 5 or 6, wherein one or more steel plates having a surface treatment film formed on the plurality of steel plates are used.
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