KR100936363B1 - Manufacturing method of cold work tool steel with small dimensional changes after heat treatments - Google Patents
Manufacturing method of cold work tool steel with small dimensional changes after heat treatments Download PDFInfo
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- KR100936363B1 KR100936363B1 KR1020070135518A KR20070135518A KR100936363B1 KR 100936363 B1 KR100936363 B1 KR 100936363B1 KR 1020070135518 A KR1020070135518 A KR 1020070135518A KR 20070135518 A KR20070135518 A KR 20070135518A KR 100936363 B1 KR100936363 B1 KR 100936363B1
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- tool steel
- heat treatment
- dimensional
- hot rolling
- cold tool
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- 238000010438 heat treatment Methods 0.000 title claims abstract description 42
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 13
- 229910000822 Cold-work tool steel Inorganic materials 0.000 title 1
- 238000005098 hot rolling Methods 0.000 claims abstract description 29
- 229910001315 Tool steel Inorganic materials 0.000 claims abstract description 21
- 238000005242 forging Methods 0.000 claims abstract description 13
- VGIPUQAQWWHEMC-UHFFFAOYSA-N [V].[Mo].[Cr] Chemical compound [V].[Mo].[Cr] VGIPUQAQWWHEMC-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000000203 mixture Substances 0.000 claims description 3
- 229910000831 Steel Inorganic materials 0.000 abstract description 8
- 239000010959 steel Substances 0.000 abstract description 8
- 239000000463 material Substances 0.000 abstract description 5
- 238000000034 method Methods 0.000 description 18
- 238000005496 tempering Methods 0.000 description 12
- 238000010791 quenching Methods 0.000 description 11
- 230000000171 quenching effect Effects 0.000 description 10
- 238000012545 processing Methods 0.000 description 8
- 150000001247 metal acetylides Chemical class 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 6
- 229910045601 alloy Inorganic materials 0.000 description 5
- 239000000956 alloy Substances 0.000 description 5
- 239000011651 chromium Substances 0.000 description 5
- 238000005096 rolling process Methods 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 229910052804 chromium Inorganic materials 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 239000011159 matrix material Substances 0.000 description 4
- 229910052750 molybdenum Inorganic materials 0.000 description 4
- 229910052720 vanadium Inorganic materials 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 3
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 3
- 230000008602 contraction Effects 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 239000011733 molybdenum Substances 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 238000001816 cooling Methods 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 230000008646 thermal stress Effects 0.000 description 2
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- VNTLIPZTSJSULJ-UHFFFAOYSA-N chromium molybdenum Chemical compound [Cr].[Mo] VNTLIPZTSJSULJ-UHFFFAOYSA-N 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000010137 moulding (plastic) Methods 0.000 description 1
- 238000000879 optical micrograph Methods 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000011282 treatment Methods 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
- B21B3/02—Rolling special iron alloys, e.g. stainless steel
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J1/00—Preparing metal stock or similar ancillary operations prior, during or post forging, e.g. heating or cooling
- B21J1/003—Selecting material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J1/00—Preparing metal stock or similar ancillary operations prior, during or post forging, e.g. heating or cooling
- B21J1/06—Heating or cooling methods or arrangements specially adapted for performing forging or pressing operations
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
본 발명은 냉간 공구강에 관한 것으로, 단조 또는 열간압연 공정에 있어서 열간가공의 개시온도를 980℃~1050℃로 하고 종료온도를 930℃~960℃로 제어함으로써 열처리시 발생하는 치수변화를 줄여 냉간 공구강 소재로 제작되는 각종 금형이나 펀치의 치수정밀도를 향상시키고, 금형이나 펀치로 가공되는 각종 부품의 치수정밀도를 향상시켜 줄 수 있는 것을 특징으로 하는 고탄소-고크롬-몰리브덴-바나듐 계 냉간 공구강의 제조방법이다.The present invention relates to a cold tool steel, in the forging or hot rolling process by controlling the start temperature of the hot working to 980 ℃ ~ 1050 ℃ and the end temperature of 930 ℃ ~ 960 ℃ by reducing the dimensional change generated during heat treatment cold tool steel Manufacture of high-carbon-high chromium-molybdenum-vanadium cold tool steels, which can improve the dimensional accuracy of various molds and punches made of materials and improve the dimensional precision of various parts processed with molds and punches. It is a way.
냉간공구강, 열간압연, 단조, 열처리, 치수변화, 제조방법 Cold work, hot rolled, forged, heat treated, dimensional change, manufacturing method
Description
본 발명은 프레스 금형, 나사 전조용 다이, 냉간 성형 롤, 박판성형 롤, 인발 다이스, 플라스틱 성형용 금형, 등의 금형 또는 다이 제작용 소재로 사용되는 냉간 공구강에 관한 것으로서, 단조 또는 열간압연 공정에서 열처리시 열간가공의 개시온도는 980℃~1050℃로 하고, 종료온도는 930℃~960℃로 제어해서 공정 탄화물 분포를 균일하고 미세화함으로써 금형가공 후 경도와 인성을 향상시키기 위해 실시되는 담금질(quenching) 및 뜨임(tempering) 열처리 단계에서 치수변화가 적게 발생되는 고탄소-고크롬-몰리브덴-바나듐(1.5C-12Cr-1.0Mo-0.25V) 계 냉간 공구강의 제조방법을 특징으로 한다.BACKGROUND OF THE
담금질과 뜨임 열처리시 발생되는 판재의 치수 변형은 압연방향에 평행한 길이방향, 폭방향, 그리고 두께방향으로 발생된다. 이와 같이 열처리 치수변화율이 큰 평강 소재를 이용해서 금형을 가공하는 경우 열처리 후 길이와 폭 방향의 치수 변화가 비례적으로 변화되지 않고 뒤틀림이 발생될 뿐만 아니라 구멍이나 나사 가공부의 원주 형상이 타원 형상으로 변형될 수 있다. 또한 열처리시 치수변화가 크게 발생하면, 금형설계시 열처리에 따른 변형을 미리 고려해서 치수설계를 하더라도 최종치수를 보정하는데 한계가 있기 때문에 치수 공차범위를 필요이상으로 크게 설계해야 한다. 결국 필요이상으로 크게 설계된 금형의 치수 공차는 금형의 치수정밀도와 지그 부품의 조립 정밀도를 감소시키고, 금형으로 가공되는 최종제품의 치수정밀도의 품질이 저하되는 결과를 초래하고, 뿐만 아니라 금형 및 지그의 수명을 감소시키는 원인을 제공하게 된다.The dimensional deformation of the plate produced during the quenching and tempering heat treatment occurs in the longitudinal direction, the width direction, and the thickness direction parallel to the rolling direction. As such, when the mold is processed using a flat steel material having a large heat treatment dimensional change rate, the dimensional change in the length and width directions after the heat treatment is not proportionally changed, distortion is generated, and the circumferential shape of the hole or the thread processing part is elliptical. It can be modified. In addition, if the dimensional change occurs largely during the heat treatment, even if the dimensional design is made in consideration of the deformation due to the heat treatment during the mold design, the final dimension should be corrected, so the dimensional tolerance range should be designed larger than necessary. As a result, dimensional tolerances of molds that are designed to be larger than necessary reduce the dimensional accuracy of the mold and the assembly accuracy of the jig parts, and result in the deterioration of the quality of the dimensional precision of the final product processed into the mold. It provides a cause for reducing the lifetime.
종래에는 상기 냉간 공구강의 열처리 치수 변형을 감소시키기 위해 인(P), 황(S), 니켈(Ni), 구리(Cu) 와 같은 불순물 농도를 매우 낮은 수준으로 감소시킨 개량합금이나 탄소(C)와 크롬(Cr)의 농도는 감소시키나, 몰리브덴(Mo)의 농도는 증가시키고, 동시에 상기 불순물 농도를 매우 낮은 수준으로 감소시킨 개량합금(JP 1999-310820)이 사용되어 왔다. 하지만 이들 개량합금의 경우에는 불순물 농도를 감소시키기 위해 값싼 스크랩을 사용하는 비율이 제한되기 때문에 원재료비가 상승하므로 종래기술에 의한 개량합금을 사용한 냉간 공구강은 기존의 냉간 공구강보다 가격이 비싼 문제점을 가지고 있다. Conventionally, an improved alloy or carbon (C) in which impurity concentrations such as phosphorus (P), sulfur (S), nickel (Ni), and copper (Cu) are reduced to a very low level in order to reduce heat treatment dimensional deformation of the cold tool steel. Improved alloys (JP 1999-310820) have been used that reduce the concentration of and chromium (Cr), but increase the concentration of molybdenum (Mo) and at the same time reduce the impurity concentration to very low levels. However, in the case of these modified alloys, since the ratio of using cheap scrap to reduce the impurity concentration is limited, the raw material costs increase, so the cold tool steels using the conventional alloys have a problem that they are more expensive than conventional cold tool steels. .
본 발명은 상기와 같은 종래기술의 문제점을 해결하기 위하여, 단조 또는 열 간압연을 할 때 열처리공정시 발생하는 치수 변형율이 작은 냉간 공구강을 제공하기 위한 것으로, 합금성분이나 불순물 농도를 종래와 동일하게 유지하되 단조 또는 열간압연이 실시되는 개시온도와 종료온도의 범위를 낮은 온도범위에서 제어함으로써 열처리 치수변화율이 작은 냉간 공구강의 제조방법을 제공하는데 그 목적이 있다.The present invention, in order to solve the problems of the prior art as described above, to provide a cold tool steel with a small dimensional strain generated during the heat treatment process when forging or hot rolling, the alloy component or impurity concentration in the same way as the conventional It is an object of the present invention to provide a method for manufacturing a cold tool steel having a small heat treatment dimensional change rate by maintaining the starting temperature and the ending temperature at which the forging or hot rolling is performed at a low temperature range.
본 발명은 냉간 공구강의 제조시 단조 또는 열간압연 공정에 있어서, 열간가공 개시온도를 980℃~1050℃로, 종료온도를 930℃~960℃로 제어하는 것을 특징으로 하는 고탄소-고크롬-몰리브덴-바나듐계 열처리 치수변화가 작은 냉간 공구강의 제조방법이다.High carbon-high chromium-molybdenum in the forging or hot rolling process in the manufacture of cold tool steel, characterized in that the hot working start temperature is controlled to 980 ℃ ~ 1050 ℃, the end temperature is 930 ℃ ~ 960 ℃ -Vanadium-based heat treatment method for manufacturing cold tool steel with small change in dimensions.
본 발명에 의하여, 낮은 온도 범위에서 열간압연을 실시할 경우, 조직이 미세하고 균일하게 분포되어, 공정 탄화물이 기지보다 경도 및 강도가 높기 때문에 일방향으로 배열될 경우에 열처리 과정에서 일어나는 기지의 팽창 및 수축을 억제하는 효과가 있다. 반면 높은 온도 범위에서 열간압연이 실시될 경우, 공정 탄화물이 조대하게 분포하여 열처리시 기지에 고용되지 못하고 잔류하기 때문에 오히려 치수변화율을 증가시킨다. According to the present invention, when hot rolling is carried out at a low temperature range, the structure is finely and uniformly distributed, so that the process carbides have higher hardness and strength than the matrix, so that the expansion of matrix caused in the heat treatment process when arranged in one direction and It is effective in suppressing shrinkage. On the other hand, when hot rolling is carried out at a high temperature range, the process carbides are coarsely distributed and are not dissolved in the matrix during heat treatment, thereby increasing the rate of dimensional change.
따라서, 본 발명에서와 같이 낮은 온도 범위에서 열간압연을 실시하면, 프레 스 금형, 나사 전조용 다이, 냉간 성형 롤, 박판 성형 롤, 등의 금형 또는 다이 제작용 소재로 사용되는 냉간 공구강의 치수정밀도를 향상시켜주고, 상기 금형에 의하여 가공되는 각종 부품의 치수정밀도를 향상시켜 주는 효과가 있다.Therefore, when hot rolling is performed in a low temperature range as in the present invention, the dimensional accuracy of cold tool steel used as a material for forming a die or die, such as a press die, a thread rolling die, a cold forming roll, a sheet forming roll, and the like It has the effect of improving the dimensional accuracy of the various parts processed by the mold.
상기 목적을 달성하기 위해, 본 발명인 냉간 공구강의 제조방법은 잉곳(Ingot)을 단조하거나 열간압연해서 평강을 제조할 때, 단조 또는 열간압연 시 실시되는 열간가공 개시온도를 980℃~1050℃로 하고 종료온도를 930℃~960℃로 제어해서 공정 탄화물 분포를 균일하고 미세하게 하는 것을 특징으로 한다. In order to achieve the above object, the present invention is a method for manufacturing cold tool steel of the present invention when manufacturing a flat steel by forging or hot rolling ingot, the hot processing start temperature is carried out during forging or hot rolling to 980 ℃ ~ 1050 ℃ It is characterized in that the end temperature is controlled at 930 ° C to 960 ° C to make the process carbide distribution uniform and fine.
냉간 공구강 소재를 이용해서 금형이나 펀치 등을 제조하는 경우, 금형이나 펀치 등을 가공하기 전에 절삭가공 또는 연삭가공을 쉽게 할 수 있도록 구상화 열처리를 실시하며, 최종적으로 경도와 인성을 부여하기 위해 담금질과 뜨임처리를 실시하게 된다. 열처리 치수변화는 최종적으로 실시되는 담금질과 뜨임처리 단계에서 발생되는 현상이고, 열처리 치수변화는 열처리시 냉간 공구강의 가공 부품이 겪는 온도 변화에 의한 열팽창, 열수축, 상변태, 그리고 내외부 온도차이에 의해 발생되는 열응력이 부품 형상에 따른 기하학적 구속과 결합되어 나타나는 결과이다. 도 1은 열처리시 상온에서 부피 a 가 온도변화에 따른 열팽창ㅇ수축과 상변태를 거쳐 다시 상온으로 냉각된 후 부피 g 로 변화되는 것을 도식적으로 나타낸 것이다. 이와 같은 부피 변화는 부품의 내외부 온도차이에 의한 열응력과 함께 복합적으로 작용하면서 실제 금형이나 펀치 등의 제품 열처리 후 치수변화로 나타나는 것이다.When manufacturing molds or punches using cold tool steel materials, before processing the molds or punches, spheroidization heat treatment is performed to make cutting or grinding process easier. Finally, hardening and Tempering is performed. The heat treatment dimensional change is a phenomenon that occurs during the final quenching and tempering treatment step, and the heat treatment dimensional change is caused by thermal expansion, heat shrinkage, phase transformation, and internal and external temperature difference due to temperature change experienced by the machined parts of cold tool steel during heat treatment. Thermal stress is the result of the combination of geometric constraints along the part geometry. Figure 1 schematically shows that the volume a at room temperature is changed to the volume g after cooling to room temperature again through thermal expansion and contraction and phase transformation according to the temperature change at room temperature. Such a volume change is combined with the thermal stress caused by the temperature difference between the inside and outside of the component, and appears as a dimensional change after heat treatment of a product such as an actual mold or punch.
또한 냉간 공구강에 있어서 열처리 치수 변화율을 감소시키기 위해서는 공정 탄화물 분포를 균일하고 미세하게 제어하는 것이 효과적이며, 이를 위해서는 단조 또는 열간압연 온도범위를 제어해야 한다.In addition, it is effective to uniformly and finely control the process carbide distribution in order to reduce the heat treatment dimensional change rate in the cold tool steel, and to control the forging or hot rolling temperature range.
냉간 공구강에 있어서는 다량의 탄소와 함께 탄화물을 형성하는 크롬, 몰리브덴, 바나듐이 합금원소로 구성되어 있기 때문에 잉곳 주조시 M7C3형 탄화물이 다량으로 정출된다. 이들 M7C3형 공정 탄화물은 단조나 열간압연 후 변형되는 방향을 따라 일방향으로 배열되는 특징이 있으며, 단조나 열간압연 후 실시되는 구상화 열처리, 담금질, 뜨임 열처리 후에도 기지에 고용되지 않고 단조방향이나 압연방향을 따라 일방향으로 배열된 형상으로 잔류된다. 도 2는 동일한 조건으로 제조된 슬라브를 이용해서 열간압연을 낮은 온도 범위(도 2-(a))에서 실시한 것과 높은 온도 범위(도 2-(b))에서 실시한 후 동일한 조건으로 구상화 열처리했을 때 얻어지는 미세조직을 비교해서 나타낸 것이다. 미세조직은 압연방향에 평행하고 판면에 수직한 단면의 광학현미경 사진으로 밝은 회색을 띤 M7C3형 공정 탄화물이 기지 내에 다량으로 분포되어있다. 도 2-(a)와 도 2-(b)의 미세조직에 있어서 M7C3형 공정 탄화물의 크기와 균일도를 비교해보면, 낮은 온도 범위에서 열간압연된 도 2-(a)의 공정 탄화물이 높은 온도 범위에서 열간압연된 도 2-(b)보다 미세하고 균일하게 분포되어 있음을 알 수 있다.When ingot casting because in the cold tool steel, a large amount of carbon to form a carbide with chromium, molybdenum, vanadium it is composed of alloying elements are crystallized in a large amount are M 7 C 3 type carbide. These M 7 C 3 type carbides are characterized by being arranged in one direction along the deformation direction after forging or hot rolling. It remains in the shape arranged in one direction along the rolling direction. FIG. 2 shows that when hot rolling is performed using a slab manufactured under the same conditions in a low temperature range (FIG. 2- (a)) and in a high temperature range (FIG. It compares and shows the obtained microstructure. The microstructure is an optical micrograph of the section parallel to the rolling direction and perpendicular to the plate surface, where light grayish M 7 C 3 type process carbides are distributed in a large amount in the matrix. Comparing the size and uniformity of the M 7 C 3 type process carbide in the microstructures of FIGS. 2- (a) and 2- (b), the process carbide of FIG. 2- (a) was hot-rolled at a low temperature range. It can be seen that the finer and more uniformly distributed than the hot rolled Figure 2- (b) in the high temperature range.
그런데, 이들 공정 탄화물은 기지보다 경도가 높고 강도가 높기 때문에 일방향으로 배열되는 경우 열처리 과정 중 일어나는 기지의 팽창이나 수축을 방해하는 역할을 한다. 특히 단조나 열간압연 후 일방향으로 배열된 공정 탄화물이 조대하게 분포하는 경우에는 담금질 열처리시 고용화 가열단계에서 기지에 고용되지 못하고 잔류되기 때문에 열처리 치수변화를 증가시키는 결과를 초래한다. However, these process carbides have a higher hardness and higher strength than the bases, and thus, when the carbides are arranged in one direction, they serve to hinder the expansion or contraction of the bases occurring during the heat treatment process. Particularly, in the case of coarse distribution of process carbides arranged in one direction after forging or hot rolling, quenching heat treatment results in an increase in dimensional change of heat treatment because it remains in the solid solution in the solid solution heating step.
따라서 열처리 치수변화율이 작은 냉간 공구강을 제조하기 위해서는 단조나 열간압연시 가공온도 범위 즉 개시온도를 980℃~1050℃로 하고 종료온도를 930℃~960℃로 하되 가능한 낮게 제어하는 것이 바람직하다.Therefore, in order to manufacture cold tool steel having a small rate of dimensional change in heat treatment, it is preferable to control the processing temperature range during forging or hot rolling, that is, the start temperature is 980 ° C. to 1050 ° C. and the end temperature is 930 ° C. to 960 ° C., but as low as possible.
또한 치수변화를 줄이기 위하여 사용되는 공구강은 공정 탄화물 분포를 균일하고 미세화함으로써 금형가공 후 경도와 인성을 향상시키기 위해 실시되는 담금질 및 뜨임 열처리 단계에서 치수변화가 적게 발생되는 고탄소-고크롬-몰리브덴-바나듐(1.5C-12Cr-1.0Mo-0.25V)계 냉간 공구강이다. 다만 상기 조성이외에도 고탄소-고크롬-몰리브덴-바나듐계를 포함할 수 있다. In addition, the tool steel used to reduce the dimensional change is made of high carbon, high chromium, molybdenum, which produces less dimensional change in the quenching and tempering heat treatment step, which is performed to improve hardness and toughness after mold processing by uniform and refined process carbide distribution. Vanadium (1.5C-12Cr-1.0Mo-0.25V) cold tool steel. However, in addition to the above composition, it may include a high carbon-high chromium-molybdenum-vanadium system.
이하 실시 예를 이용해서 본 발명을 더욱 상세히 설명한다. The present invention will be described in more detail with reference to the following examples.
실시예Example
본 발명의 실시예에서는 용해(잉곳 제조)-단조(슬라브)-열간압연(평강)-구상화 소둔-시편가공-초기 치수 측정-담금질 및 뜨임 열처리-최종 치수 측정을 거쳐 열처리시 발생되는 치수변화를 평가하였다. 잉곳의 화학조성(중량비) 1.51% C, 0.20% Si, 0.24% Mn, 0.02% P, 0.002% S, 0.16% Ni, 11.6% Cr, 0.85% Mo, 0.25% V, 0.09% Cu 이었으며, 잉곳의 중량은 3 ton 이었다. 상기 잉곳을 1160℃로 재가열하여 단조해서 슬라브를 제조하였으며, 슬라브 두께는 150 mm 로 하였다. 상기 슬라브를 1190℃로 가열한 후 열간압연을 실시하여 최종두께 30 mm 의 평강을 제조하였 는데, 열간압연시 열간압연 개시온도와 종료온도를 변화시켜 비교하였다. 이상과 같이 제조된 평강에 대하여 870℃에서 3시간 동안 구상화 소둔을 실시한 후 치수변화 평가용 시편을 제작하였으며, 시편 치수는 두께 25 mm, 폭 100 mm, 길이 110 mm로 하였다. 시편가공 후 치수정밀도 1 micrometer를 갖는 정밀 측정기를 이용해서 담금질 및 뜨임 열처리 전 초기치수를 측정하였다. 담금질 및 뜨임 열처리는 진공열처리로를 이용해서 실시하였다. 담금질은 1030℃로 가열 후 질소가스로 강제 냉각해서 실시하였다. 뜨임은 2단계로 실시하였는데, 1단계는 500℃로 가열 후 공냉, 2단계는 480℃로 가열 후 공냉하였다. 담금질 및 뜨임 열처리 후 열처리 과정에서 발생되는 치수변화량을 측정하기 위해 상기 정밀 측정기를 이용해서 열처리 후 최종치수를 측정하였다. 상기 시편 치수 측정 시 측정위치는 두께, 폭, 길이를 균등 분할해서 5개소씩 측정해서 평균값을 구했다. 이상과 같이 측정된 담금질 및 뜨임 열처리 전,후 치수로부터 다음 식과 같이 두께, 폭, 길이에 대한 각각의 치수변화율을 계산하였다.In the embodiment of the present invention, melting (ingot production)-forging (slab)-hot rolling (flat steel)-spheroidization annealing-specimen processing-initial dimensional measurement-quenching and tempering heat treatment-final dimensional change through the dimensional change generated during heat treatment Evaluated. Ingot chemical composition (weight ratio): 1.51% C, 0.20% Si, 0.24% Mn, 0.02% P, 0.002% S, 0.16% Ni, 11.6% Cr, 0.85% Mo, 0.25% V, 0.09% Cu The weight was 3 ton. The ingot was reheated to 1160 ° C. and forged to prepare a slab, and the slab thickness was 150 mm. The slab was heated to 1190 ° C. and then hot rolled to prepare a flat steel having a final thickness of 30 mm. The hot rolling was compared by changing the starting and ending temperatures of the hot rolling. After the spheroidizing annealing at 870 ℃ for 3 hours for the flat steel prepared as described above to prepare a specimen for dimensional change evaluation, the specimen dimensions were 25 mm thick, 100 mm wide, 110 mm long. After the specimen processing, the initial dimension of the quenching and tempering heat treatment was measured using a precision measuring instrument having a dimensional accuracy of 1 micrometer. Quenching and tempering heat treatment were carried out using a vacuum heat treatment furnace. Quenching was performed by forcibly cooling with nitrogen gas after heating to 1030 ° C. Tempering was carried out in two stages, the first stage was air cooled after heating to 500 ℃, the second stage was air cooled after heating to 480 ℃. After quenching and tempering heat treatment, the final dimension after heat treatment was measured using the precision measuring instrument to measure the amount of dimensional change generated during the heat treatment. When measuring the size of the specimen, the measurement position was equally divided by thickness, width, and length, and measured at five places to obtain an average value. From the dimensions before and after the quenching and tempering heat treatment measured as described above, the rate of change of each dimension for thickness, width, and length was calculated as follows.
그리고, 위와 같이 두께, 폭, 길이에 대하여 얻어진 치수변화율을 이용해서 다음 식과 같이 평균 치수 변화율(%)을 계산하였다.Then, using the dimensional change rate obtained for the thickness, width, and length as described above, the average dimensional change rate (%) was calculated as in the following equation.
실시예 1은 열간압연 개시온도를 1050℃로, 종료온도를 930℃ 하였으며, 평 균치수변화율은 0.023%로 나타났다. 실시예 2는 열간압연 개시온도를 1050℃로, 종료온도를 960℃ 하였으며, 평균치수변화율은 0.018%로 나타났다. 실시예 3은 열간압연 개시온도를 1020℃로, 종료온도를 930℃ 하였으며, 평균치수변화율은 0.015%로 나타났다. 실시예 4는 열간압연 개시온도를 980℃로, 종료온도를 930℃ 하였으며, 평균치수변화율은 0.013%으로 나타났다.In Example 1, the hot rolling start temperature was 1050 ° C., the end temperature was 930 ° C., and the average dimension change rate was 0.023%. In Example 2, the hot rolling start temperature was 1050 ° C., the end temperature was 960 ° C., and the average dimension change rate was 0.018%. In Example 3, the hot rolling start temperature was 1020 ° C., the end temperature was 930 ° C., and the average dimension change rate was 0.015%. In Example 4, the hot rolling start temperature was 980 ° C., the end temperature was 930 ° C., and the average dimension change rate was 0.013%.
비교예Comparative example
비교예 1은 열간압연 개시온도를 1150℃로, 종료온도를 1030℃ 하였으며, 평균치수변화율은 0.058%로 나타났다. 비교예 2는 열간압연 개시온도를 1150℃로, 종료온도를 960℃ 하였으며, 평균치수변화율은 0.045%로 나타났다. 비교예 3은 열간압연 개시온도를 1130℃로, 종료온도를 1030℃ 하였으며, 평균치수변화율은 0.030%으로 나타났다. 비교예 4는 열간압연 개시온도를 1100℃로, 종료온도를 980℃ 하였으며, 평균치수변화율은 0.037%으로 크게 나타났다.In Comparative Example 1, the hot rolling start temperature was 1150 ° C., the end temperature was 1030 ° C., and the average dimension change rate was 0.058%. In Comparative Example 2, the hot rolling start temperature was 1150 ° C., the end temperature was 960 ° C., and the average dimension change rate was 0.045%. In Comparative Example 3, the hot rolling start temperature was 1130 ° C., the end temperature was 1030 ° C., and the average dimension change rate was 0.030%. In Comparative Example 4, the hot rolling start temperature was 1100 ° C., the end temperature was 980 ° C., and the average dimensional change rate was 0.037%.
표 1Table 1
표 1에서 본 발명의 실시예의 경우 평균치수변화율이 0.023% 이하이지만, 비교예의 경우 평균 치수 변화율이 0.030% 이상으로 크게 나타나고 있다. 따라서 열간가공 개시온도를 980℃~1050℃로, 종료온도를 930℃~960℃로 제어하는 하는 것이 바람직하다.In Example 1 of the present invention, the average dimensional change rate is 0.023% or less, but in the comparative example, the average dimensional change rate is larger than 0.030%. Therefore, it is preferable to control hot processing start temperature to 980 degreeC-1050 degreeC, and end temperature to 930 degreeC-960 degreeC.
상기에서는 본 발명의 바람직한 실시예에 대하여 설명하였지만, 본 발명은 이에 한정되는 것이 아니고 특허청구범위 및 발명의 상세한 설명의 범위안에서 여러가지로 변형하여 실시하는 것이 가능하며, 이 또한 본 발명의 범위에 속하는 것은 당연하다.While the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention. Of course.
도 1은 열처리 중 발생되는 열팽창,수축과 상변태에 따른 부피변화 모식도이다.1 is a schematic diagram of volume change caused by thermal expansion, contraction and phase transformation generated during heat treatment.
도 2-(a)는 낮은 온도범위에서 열간압연하고 구상화 열처리 후 미세조직이다.2- (a) is a microstructure after hot rolling in a low temperature range and spheroidizing heat treatment.
도 2-(b)는 높은 온도범위에서 열간압연하고 구상화 열처리 후 미세조직이다.2- (b) shows the microstructure after hot rolling and spheroidizing heat treatment at high temperature range.
Claims (3)
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| Application Number | Priority Date | Filing Date | Title |
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| KR1020070135518A KR100936363B1 (en) | 2007-12-21 | 2007-12-21 | Manufacturing method of cold work tool steel with small dimensional changes after heat treatments |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20190120567A (en) | 2018-04-16 | 2019-10-24 | 나이프코리아 주식회사 | Mold reinforced with composite material and method of manufacturing the same |
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| WO2010006543A1 (en) * | 2008-07-17 | 2010-01-21 | Yi Xiaojie | An electric hand-held binding apparatus |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04116122A (en) * | 1990-09-07 | 1992-04-16 | Nkk Corp | Production of cold die steel excellent in machinability |
| JPH11158544A (en) | 1997-11-26 | 1999-06-15 | Daido Steel Co Ltd | Production of cold die steel |
| KR19990050962A (en) * | 1997-12-17 | 1999-07-05 | 이구택 | Manufacturing method of cold work tool steel with excellent wear resistance |
| KR20000041284A (en) * | 1998-12-22 | 2000-07-15 | 한수양 | Method for producing tool steel for cold-processing which has excellent toughness and abrasion resistance |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04116122A (en) * | 1990-09-07 | 1992-04-16 | Nkk Corp | Production of cold die steel excellent in machinability |
| JPH11158544A (en) | 1997-11-26 | 1999-06-15 | Daido Steel Co Ltd | Production of cold die steel |
| KR19990050962A (en) * | 1997-12-17 | 1999-07-05 | 이구택 | Manufacturing method of cold work tool steel with excellent wear resistance |
| KR20000041284A (en) * | 1998-12-22 | 2000-07-15 | 한수양 | Method for producing tool steel for cold-processing which has excellent toughness and abrasion resistance |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20190120567A (en) | 2018-04-16 | 2019-10-24 | 나이프코리아 주식회사 | Mold reinforced with composite material and method of manufacturing the same |
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| KR20090067759A (en) | 2009-06-25 |
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