CN113732263B - Sleeve for die casting and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a sleeve for die casting and a method for manufacturing the same. A sleeve for die casting having a flow path therein, wherein a melt supply port for supplying a molten metal from the outside to the flow path penetrates from the inner surface to the outer surface of the sleeve for die casting. At least a portion of the inner surface forming the flow path facing the melt supply port is formed of a material having, in mass%, C:0.4% or more and 2.5% or less, si: less than 1.0%, mn: less than 1.0%, cr:3.0% or more and 12.0% or less, mo: less than 1.0%, and the balance being Fe and impurities.

Description

Sleeve for die casting and manufacturing method thereof

This application is a divisional application of:

Invention name: Sleeve for die casting and its manufacturing method

Application number: 201780053624.1

technical field

The present invention relates to a die-casting sleeve as a component of a die-casting device and a manufacturing method thereof.

Background technique

A die-casting sleeve, which is one of the components of a die-casting device used for die-casting, generally has a cylindrical shape. A molten metal supply port for supplying molten metal to an internal flow path is provided on a side surface of the cylindrical die-casting sleeve. Then, during operation of the die casting apparatus, molten metal such as aluminum or aluminum alloy, zinc or zinc alloy is supplied into the cylinder from the above-mentioned molten solution supply port. The supplied molten metal is injected from the molten injection port toward the cavity through the plunger. As a material for such a sleeve for die casting, for example, SKD61, which is a standard steel grade of "alloy tool steel materials" of JIS-G-4404:2006, is often used. In addition, a die-casting sleeve in which surface treatment such as nitriding treatment is performed on the inner surface of the die-casting sleeve made of SKD61 or the like is proposed (Patent Documents 1 and 2).

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2005-205666

Patent Document 2: Japanese Patent Laid-Open No. 2012-219340

Contents of the invention

The problem to be solved by the invention

One of the important characteristics required for die-casting sleeves is resistance to melting. Melting loss refers to the loss of the sleeve material caused by the contact of the molten metal with the inner surface of the die-casting sleeve. Then, when the wear is severe, injection abnormalities and the like are caused during casting, and the life of the die-casting sleeve is shortened. Then, when the inner surface of the die-casting sleeve is subjected to surface treatment, a certain degree of improvement effect of erosion resistance is observed, but further improvement in erosion resistance is required.

An object of the present invention is to provide a sleeve for die-casting excellent in erosion resistance and a method for producing the same.

solutions to problems

According to one aspect of the present disclosure, there can be provided a die-casting sleeve having a flow path inside, and in the die-casting sleeve, a molten metal supply port for supplying molten metal to the flow path from the outside. Penetrating from the inner surface to the outer surface of the die-casting sleeve, at least the part of the inner surface forming the flow path facing the melt supply port has, in mass %, C: 0.4% or more and 2.5% The raw material is composed of Si: 1.0% or less, Mn: 1.0% or less, Cr: 3.0% or more and 12.0% or less, and the remainder is Fe and impurities.

In addition, according to one aspect of the present disclosure, it is possible to provide a method of manufacturing a die-casting sleeve having a flow path inside for supplying molten metal to the flow path from the outside. The mouth penetrates from the outer surface to the inner surface. In the method of manufacturing the die-casting sleeve, a preliminary body constituting the die-casting sleeve is prepared, and at least the molten liquid is supplied to the inner surface forming the flow path. The part facing the mouth or the part facing the part constituting the melt supply port is provided with, in mass %, C: 0.4% to 2.5%, Si: 1.0% or less, Mn: 1.0% or less, Cr: A raw material having a component composition of 3.0% to 12.0% and the remainder being Fe and impurities.

Invention effect

According to the present invention, it is possible to provide a sleeve for die-casting excellent in erosion resistance and a method of manufacturing the same.

Description of drawings

Fig. 1 is a schematic diagram showing a cross-sectional structure of a die-casting sleeve according to the present invention.

Fig. 2 is a schematic view showing a cross-sectional structure of another die-casting sleeve according to the present invention.

Fig. 3 is a photograph substituted for a drawing showing the appearance of a die-casting sleeve used in an example.

4 is a photograph substituted for a drawing showing the inner surface of the die-casting sleeve of the example of the present invention after die-casting, at the position where the melt supply port is provided.

FIG. 5 is a photograph substituted for a drawing showing the inner surface of a die-casting sleeve of a comparative example after die-casting at a position where a melt supply port is provided.

6 is a photograph substituted for a drawing showing the inner surface of the die-casting sleeve of the example of the present invention after die-casting, at the position where the melt supply port is provided.

FIG. 7 is a photograph substituted for a drawing showing the inner surface of the die-casting sleeve of the comparative example after die-casting at the position where the melt supply port is provided.

FIG. 8 is a diagram showing the shape of a test piece used in a melting loss test in an example.

FIG. 9 is a diagram illustrating the outline of a melting loss test in an example.

Detailed ways

The inventors of the present invention investigated the state of melting loss occurring on the inner surface of the die-casting sleeve. As a result, it was found that the above-mentioned melting loss is conspicuous in the inner surface of the die-casting sleeve, especially in the portion facing the melt supply port. From this, it was found that the melting resistance of the entire die-casting sleeve can be improved by re-examining the material constituting at least this portion, and completed the present invention.

It should be noted that the above-mentioned "cylindrical shape" means a shape in which a cavity serving as a flow path is formed inside, such as a cylindrical shape or a square cylindrical shape. The die-casting sleeve may have a shape in which a cylindrical portion and a square tubular portion are combined. A protrusion, a flange, etc. may be provided on the outer peripheral surface of the cylindrical main body of the die-casting sleeve.

The shape of the flow path may also be a column shape, a prism shape, or a combination thereof. A cylindrical flow path may be formed in a cylindrical die-casting sleeve. Alternatively, a prismatic flow path may be formed in a cylindrical die-casting sleeve.

The melt supply port is provided on the outer peripheral surface of the cylindrical die-casting sleeve. The die-casting sleeve is used with the melt supply port opening upward and the flow path extending substantially in the horizontal direction.

Furthermore, melting loss includes: "physical melting loss" caused by the impact energy brought by the falling of molten metal; and "chemical melting loss" caused by chemical reaction with molten metal. Then, as a result of the investigation, it was found that physical erosion has a great influence on the erosion resistance at the portion facing the melt supply port in the inner surface forming the flow path. At this location, the molten metal supplied from the molten metal supply port to the flow path collides "violently", so that significant physical melting loss tends to occur.

In addition, the bush for die-casting which provided the surface treatment layer with low chemical reactivity with molten metal on the blank was proposed. This surface treatment layer is provided in order not to directly contact the material for forming the die-casting sleeve with the molten metal, and has a certain effect on chemical melting loss. However, for the physical melting loss caused by the mechanical factors of the molten metal, the strength of the surface treatment layer is limited, and the effect of suppressing the physical melting loss only by the surface treatment layer is limited.

Furthermore, in the recent die-casting, casting under special conditions is increasing along with the improvement of the quality of the produced die-casting products.

For example, in the case of general aluminum die-casting, the casting material uses ADC12 (Fe: 1.3% by mass or less) stipulated in JIS-H-5302:2006 "Aluminum alloy die-casting", and the temperature of the molten metal during casting is It is 660～680℃. Some automobile parts have been changed from iron to aluminum alloy in order to reduce weight. Such a change sometimes compensates for the decrease in the strength of the die-cast product that accompanies the change from iron to aluminum alloy.

In order to perform this strength compensation, it is effective to suppress the occurrence of "cavity" in the die-cast product and the like. Therefore, a method of increasing the melt fluidity (fluidity) of the molten metal by increasing the temperature of the molten metal of the aluminum alloy is often used. Then, when the temperature of the molten metal rises to a special level of "700° C. or higher", the chemical melting loss generated between the molten metal and the inner surface of the die-casting sleeve is accelerated.

In addition, in order to perform the above-mentioned strength compensation, a method of increasing the strength of the die-cast product by reducing the amount of Fe in the aluminum alloy is often used. Then, in the case of a special aluminum alloy in which the Fe content is reduced to a level of "0%", chemical melting loss is accelerated.

In such a special die-casting, even a conventional die-casting sleeve having a surface treatment layer has a limited effect of suppressing chemical melting loss.

Thus, the present inventors have found that there is room for improvement in the following two aspects, that is, reducing the physical melting loss at the portion opposite to the melt supply port in the inner surface forming the flow path; chemical melting loss.

Therefore, the present inventors first sought a blank for a sleeve for die-casting (hereinafter simply referred to as "sleeve blank") that is highly resistant to physical impact when molten metal is supplied and has low chemical reactivity with molten metal. Were studied. As a result, it was found that the sleeve material "has, in mass %, C: 0.4% to 2.5%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 3.0% % and 12.0% or less, with the rest being Fe and impurities" is effective. Hereinafter, the above-mentioned component composition will be described.

C: 0.4% by mass or more and 2.5% by mass or less (hereinafter, mass% is abbreviated as "%")

C is an element that bonds with Cr, W, Mo, V, and Nb to form carbides to improve the wear resistance of the die-casting sleeve. Improvement in abrasion resistance is effective in suppressing physical melting loss. However, when too much, toughness will fall. Therefore, from the viewpoint of balancing with the Cr, W, Mo, V, and Nb contents described later, it is 0.4% or more and 2.5% or less.

In addition, it is preferable that C is 0.4 % or more and less than 1.0 %. When the C content is within this range, it is easy to balance the toughness and high-temperature strength of the sleeve material. More preferably, C is 0.9% or less. Then, it is still more preferable that C is 0.8% or less, and it is particularly preferable that C is 0.6% or less. In addition, it is more preferable that C exceeds 0.42%. Then, it is still more preferable that C is 0.43% or more, and it is particularly preferable that C is 0.44% or more.

Alternatively, it is preferable that C is not less than 1.0% and not more than 2.5%, and in this case, it is preferable that the sleeve blank is a sintered product obtained by sintering a powder material. Then, preferably, the sintered product is obtained by sintering metal powder having the same composition as that of the sleeve blank to be obtained. Preferably, at the time of sintering, HIP (Hot Isostatic Pressing) treatment is used. Generally speaking, as the C content increases, the high-temperature strength of the billet increases, but carbides tend to become coarser or segregate easily, and the toughness tends to decrease. However, by sintering the metal powder, carbides in the structure are easily formed finely and uniformly, and the structure itself is easily made finer, so it is easy to improve the toughness of the billet. More preferably, C is 1.2% or more. More preferably, C is 1.5% or more. Still more preferably, C is 1.7% or more. In addition, it is more preferable that C is 2.3% or less.

・Si: 1.0% or less

Si is generally used as a deoxidizer in the melting process. Then, there is an effect of improving the machinability of the sleeve blank. However, if too much, the toughness of a sleeve material will fall. Therefore, Si is made 1.0% or less. Preferably it is 0.6% or less. More preferably, it is 0.5% or less. In addition, the lower limit of Si is not particularly specified (it can be set to 0%), but it is preferably more than 0%. The amount of Si is more preferably 0.1% or more.

・Mn: 1.0% or less

Mn is used as a deoxidizer similarly to Si. Then, there is an effect of improving hardenability and imparting moderate quenching and tempering hardness to the die-casting sleeve. However, if too much, the residual austenite will increase in the structure after quenching and tempering, and toughness will fall. Therefore, Mn is made 1.0% or less. Preferably it is 0.7% or less. More preferably, it is 0.6% or less. In addition, the lower limit of Mn is not particularly specified (it can be set to 0%), but it is preferably more than 0%. The amount of Mn is more preferably 0.1% or more. More preferably, it is 0.2% or more.

・Cr: 3.0% to 12.0%

Cr is an element effective for improving the hardenability and for forming carbides to improve the wear resistance of the sleeve material. Improvement in abrasion resistance is effective in suppressing physical melting loss. In addition, Cr has a melting point of about 1903°C, which is higher than Fe's melting point (about 1539°C), and is an element that hardly reacts with molten metal. Therefore, Cr is an element effective for suppressing chemical melting loss. However, if too much, toughness and high temperature strength will fall. Therefore, Cr is 3.0% or more and 12.0% or less. Preferably it is 3.5% or more. More preferably, it is 4.0% or more. In addition, it is preferably 11.0% or less.

In addition, considering the characteristic relationship between the toughness required for the die-casting sleeve and the erosion resistance, when emphasizing the erosion resistance, it is preferable to make Cr 7.0% or more. More preferably, it is 8.0% or more, Especially preferably, it is 9.0% or more. In addition, when toughness is important, it is preferable to make Cr less than 7.0%. It is more preferably 6.0% or less, particularly preferably 5.0% or less.

In addition to the above-mentioned types of elements, the above-mentioned sleeve blank may contain one or more elements among Mo and W. Preferably, Mo is less than 1.0%, or 1.6% or more and 15.0% or less according to the relational expression (Mo+1/2W). Specifying Mo to be less than 1.0% assumes that Mo enters the sleeve material as an impurity, and Mo is not actively contained in the sleeve material. Mo itself is a relatively expensive material. In addition, if Mo is mixed into the billet, the mechanical strength of the billet will increase, so that the workability of the billet will become difficult. Therefore, a sleeve material in which Mo is not actively mixed and whose Mo content is less than 1.0% can be provided at relatively low cost and is not difficult to process, so it is preferable. In this case, Mo is more preferably 0.5% or less, further preferably 0.3% or less, still more preferably 0.15% or less. Then, the lower limit of Mo can be set to 0%.

・Mo, W: 1.6% or more and 15.0% or less based on the relational expression (Mo+1/2W)

Mo and W are elements that bond with C to form carbides, impart wear resistance to the die-casting sleeve, and suppress physical melting loss. In addition, the melting point of Mo is about 2620° C., and the melting point of W is about 3380° C., which are higher than the melting point of Fe. Mo and W are elements effective also in suppressing chemical melting loss. Next, it is an element that has a large secondary hardening effect during tempering and can also impart high-temperature strength. However, if too much, machinability and toughness will fall.

Mo and W can be contained individually or in combination as needed. Since the atomic weight of W is about twice that of Mo, the content at this time can be specified together with the "Mo equivalent" defined by the relational formula (Mo+1/2W). Then, in the present invention, when at least one of Mo and W is contained, it is necessary to contain 1.6% or more in the above relational expression. More preferably, it is 2.0% or more. Particularly preferably, it is 2.5% or more. Then, at least one of Mo and W may be contained by a value obtained from the relational expression (Mo+1/2W) of 15.0% or less. Preferably it is 10.0% or less. More preferably, it is 5.0% or less. However, when emphasis is placed on toughness, etc., it is particularly preferably 3.0% or less.

In addition, it is also preferable to contain Mo: 1.0% or more, and 1/2W: 0.6% or more about each element of Mo and W.

The above-mentioned sleeve material may contain V in addition to the above-mentioned kinds of elements.

・V: 6.0% or less

V is an element that bonds with C to form a hard carbide, contributes to the improvement of wear resistance of the die-casting sleeve, and suppresses physical melting loss. Then, V has a melting point of about 1847° C., which is higher than that of Fe, and is an element that effectively functions also to suppress chemical melting loss. However, when too much, toughness will fall. Therefore, V may be contained in an amount of 6.0% or less if necessary. Preferably it is 4.0% or less. More preferably, it is 3.0% or less. More preferably, it is 2.0% or less. In addition, when V is contained, it is preferably 0.5% or more. More preferably, it is 1.0% or more. More preferably, it is 1.1% or more. More than 1.2% is particularly preferable.

In addition, the above-mentioned sleeve material may contain one or more elements of Co and Nb in addition to the above-mentioned types of elements.

Co: 10.0% or less

Co is an element that dissolves in a matrix and improves the strength and heat resistance of the sleeve material. However, when too much, toughness will fall. Therefore, in the present invention, Co may be contained in an amount of 10.0% or less as necessary. Preferably it is 5.0% or less. More preferably, it is 3.0% or less. Particularly preferably, it is 2.0% or less. In addition, the lower limit of Co is not particularly specified (it can be set to 0%), but it can also be set to 0% or more. When Co is contained, it is preferably 0.5% or more.

・Nb: 3.0% or less

Nb is an element that forms carbides, strengthens the matrix of the sleeve material, and improves wear resistance. In addition, it has a melting point as high as about 2415° C., and is an element that acts to suppress chemical melting loss. However, if too much, the machinability of a sleeve material will fall. Therefore, Nb may be contained in an amount of 3.0% or less as necessary. Preferably it is 2.0% or less. More preferably, it is 1.0% or less. In addition, the lower limit of Nb is not particularly specified (it may be 0%), but may be 0% or more. When Nb is contained, the above effects can be obtained by containing 0.01% or more.

P, S, Ni, Cu, Al, Ca, Mg, O (oxygen), and N (nitrogen) are elements that may remain in the billet as impurities. In the present invention, it is preferable that these elements are as small as possible. However, on the other hand, a small amount may be contained in order to obtain additional effects such as control of the shape of inclusions, improvement of other mechanical properties, and improvement of manufacturing efficiency. In this case, if 0≤P≤0.05%, 0≤S≤0.05%, 0≤Ni≤1.0%, 0≤Cu≤0.3%, 0≤Al≤0.3%, 0≤Ca≤0.02%, 0 The ranges of ≤Mg≤0.02%, 0≤O≤0.03%, and 0≤N≤0.05% are sufficiently acceptable.

In the die-casting sleeve, by constituting "at least the part of the inner surface forming the flow path facing the melt supply port" from the sleeve blank having the above composition, it is possible to suppress the Significant physical melting loss at the site. And since it is a component composition effective also for suppression of chemical melt loss, the melt loss resistance of the whole die-casting sleeve can be improved.

FIG. 1 is a schematic diagram of a sleeve 1 for die casting. As shown in FIG. 1 , the die-casting sleeve 1 has a melt supply port 2 opening upward, a melt injection port 6 opening leftward, and a plunger insertion port 8 opening rightward. A flow path 7 is provided inside the die-casting sleeve 1 . A molten metal supply port 2 for supplying molten metal to the flow path 7 from the outside penetrates from the inner surface to the outer surface of the die-casting sleeve 1 . The melt supplied from the outside to the flow path 7 through the melt supply port 2 is pushed by a plunger (not shown) inserted through the plunger insertion port 8 , and is injected to the outside (cavity) from the melt injection port 6 .

An example of a method of manufacturing such a die-casting sleeve 1 will be described with reference to FIG. 1 .

First, preparation body 3 is prepared. In this embodiment, the preparation body 3 is a cylindrical member. A part of the inner surface of the preparation body 3 forms a part of the flow path 7 . A part of the inner surface of the preparation body 3 is provided with an enlarged diameter portion 3 a having a diameter larger than that of the flow path 7 . A first opening 3 b forming a part of the melt supply port 2 is provided on a side surface of the preparation body 3 .

Next, the tubular member 5 is disposed on the enlarged diameter portion 3a. The outer diameter of the member 5 is the same as or slightly larger than the inner diameter of the enlarged diameter portion 3a. The inner surface of the member 5 forms a flow path 7 . The member 5 is provided with a second opening 5 a forming the melt supply port 2 together with the first opening 3 b. At least a portion 4 of the inner surface of the member 5 opposite to the second opening 5a is formed from a sleeve blank having the composition described above. In the present embodiment, the entire component 5 is formed from a sleeve blank having the composition described above. By combining the preparatory body 3 and the member 5 in this way, it is possible to manufacture the die-casting sleeve 1 in which the portion 4 facing the melt supply port 2 is composed of a material having the composition described above.

Then, a part or the whole of the die-casting sleeve 1 may be heat-treated (quenched and tempered) as necessary to adjust to a predetermined hardness.

It should be noted that, in the above-mentioned embodiment, the example in which the melt supply port 2 is formed by combining the preparation body 3 having the first opening 3b and the member 5 having the second opening 5a has been described, but the present invention Not limited to this. The melt supply port may also be formed by combining the preparation body 3 without the first opening and the member 5 without the second opening, and forming a through hole through the preparation body 3 and the member 5 from the outside to the inside. 2. That is to say, it can be as follows: for the preparation body 3 provided with the melt supply port 2, in its "position opposite to the melt supply port", a sleeve blank (member 5) having the above-mentioned composition is set, It is also possible to arrange a sleeve blank (member 5 ) having the above-mentioned composition on the "position opposite to the portion constituting the melt supply port" of the preparatory body 3 before the melt supply port 2 is provided.

It should be noted that the member 5 having the above-mentioned composition can be a casting or a sintered product produced by powder metallurgy. Then, in addition to disposing the member 5 having the above-mentioned composition on the preparation body 3, for example, a material having the above-mentioned composition may be lined (lining) by methods such as surfacing welding and thermal spraying, or shrink fit (shrink fit) A ring-shaped part (inner sleeve: inner sleeve) composed of the above components. In the case of the method performed by shrink fitting, compressive stress can be applied to the ring-shaped member, and therefore cracks can be suppressed from occurring in the ring-shaped member.

In particular, in the case where the sleeve blank having the above-mentioned composition is a "pre-formed article before installation" such as a cylindrical member or an annular member, the preparation body 3 and the member 5 may be separately prepared before disposing the member 5. heat treatment. Thereby, it is possible to adjust to a preferable hardness at each part of the die-casting sleeve 1 .

For example, if the preparation body 3 (that is, in the case of FIG. 1, the inner surface of the flow path 7 other than the inner surface of the member 5) is adjusted to a hardness of "40 to 48HRC" that emphasizes toughness, on the other hand, Adjusting the member 5 to a hardness of "50 HRC or more" that emphasizes the erosion resistance is effective for improving the life of the die-casting sleeve 1 as a whole.

For example, it is preferable to adjust the hardness of the member 5 to a range of 50 to 75 HRC. By increasing the hardness of the member 5, the compressive strength of the member 5 is increased, and the resistance to physical melting loss is improved. In addition, it is also considered that carbides in the metal structure of the member 5 are enriched and distributed uniformly with the above-mentioned heat treatment, contributing to the improvement of resistance to physical melting loss. In other words, the harder the member 5 is, the more resistant it is to physical erosion, which is preferable.

Then, in order to harden the member 5, it is effective to increase the C content of the member 5, for example, it is preferable to set the C content to 1.0% or more. However, in the case of the member 5 having such a composition, coarse carbides are likely to be formed in the structure, and the toughness may decrease. Therefore, it is preferable that the member 5 having a C content of 1.0% or more is, for example, the above-mentioned "sintered product". As a result, carbides in the structure of the member 5 can be formed finely and uniformly, and the structure itself can be made finer, which contributes to maintaining and improving excellent toughness. In this case, sufficient toughness can be ensured regardless of whether the member 5 is adjusted to a hardness of "more than 60 HRC" or actually adjusted to a hardness of about 75 HRC.

As an example of the above composition with a C content of 1.0% or more, for example, C: 1.0% to 2.5%; Si: 1.0% or less; Mn: 1.0% or less; Cr: 3.0% to 12.0% or less. One or both of Mo and W obtained from the relational formula (Mo+1/2W): 10.0% to 15.0%; V: 3.0% to 6.0%; the remainder is Fe and impurities composition. Then, this component composition may further contain Co: 10.0% or less, Nb: 3.0% or less, and at least one of Co and Nb.

When the C content is set to be 1.0% or more as described above, since it is easy to increase the hardness of the member 5, it is preferable. However, if the C content is less than 1.0%, it is effective from the viewpoint of suppressing cracks of the member 5 caused by thermal shock and economic efficiency as described in detail below, and the C content is also preferably less than 1.0%.

The hardness of the member 5 is preferably "60 HRC or less" in consideration of suppressing cracks of the member 5 due to thermal shock. More preferably below 58HRC, even more preferably less than 55HRC, even more preferably less than 54HRC. Then, in the case of the member 5 having such hardness, for example, the C content can be set to be less than 1.0%. Thereby, even if the member 5 is cast (even if it is not sintered), excellent toughness can be ensured. As the composition with the C content of less than 1.0%, for example, C: 0.4% to less than 1.0%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 3.0% to less than 7.0%, according to the relational expression One or both of Mo and W obtained by (Mo+1/2W): 1.6% to 15.0%, V: 0.5% to 6.0%, and the remainder is Fe and impurities. Then, this component composition may further contain Co: 10.0% or less, Nb: 3.0% or less, and at least one of Co and Nb.

It should be noted that, of course, the member 5 with C less than 1.0% can also be a sintered product.

On the other hand, when the member 5 is a "installed and molded article" such as a welded material or a thermally sprayed material, a part or the whole of the die-casting sleeve 1 after the member 5 is arranged is heat-treated as described above. Then, when heat-treating the entire die-casting sleeve 1 "simultaneously", in both the preparation body 3 and the member 5, a material that can achieve the desired balance of hardness and toughness under the common heat-treatment conditions is selected. (ingredient composition) is effective. Alternatively, optimal heat treatment conditions for either the preparation 3 or the member 5 may be selected. At this time, depending on the target hardness (heat treatment conditions) of the member 5, either of the above-mentioned composition having a C content of 1.0% or more or a composition having a C content of less than 1.0% may be applied to the component composition of the member 5 . It should be noted that, in the case of applying the method of welding or thermal spraying to the member 5 , the possibility that the arranged member 5 deviates or detaches from the inner surface of the preparation body 3 is reduced.

According to the above-mentioned manufacturing method, a part (preparation body 3) that does not require special measures against melting loss can be manufactured from a general-purpose/inexpensive material such as SKD61, so it is advantageous to reduce the time and cost required for manufacturing. In addition, parts that require measures against melting loss and parts that do not require measures against melting loss can be produced separately, so that optimum mechanical properties (for example, hardness, etc.) can be adjusted for each part. In other words, in the die casting sleeve of the present invention, it is preferable that at least a part of the inner surface forming the flow path facing the melt supply port is formed of a material (sleeve material) having the above-mentioned composition. The inner surface other than the portion facing the melt supply port is made of "other material" having a composition different from that of the above-mentioned sleeve material.

The above-mentioned "at least the portion facing the melt supply port" can be defined as, for example, "the whole area from the portion opposite to the melt supply port to the portion of the melt supply port in the cylindrical inner surface forming the flow path." Peripheral parts (for example, all inner surfaces of the member 5 in Figure 1)". In addition, the above-mentioned "at least the portion facing the melt supply port" can be set as, for example, relative to the total length of the flow path (the length from the plunger insertion port 8 to the melt injection port 6 in FIG. 1 ), including the "The length of half or less of the total length (for example, the entire inner surface of the member 5 in FIG. 1)" of the portion facing the liquid supply port.

In addition, the composition of the above-mentioned "other materials" can be, for example, in mass %, C: 0.30% to 0.50%, Si: 1.5% or less, Mn: 1.0% or less, Cr: 4.0% to 6.0% One or both of Mo and W obtained from the following relational formula (Mo+1/2W): 0.8% or more and less than 1.6%, V: 0.3% or more and 1.5% or less, Co: 0% or more and 1.0% % or less, Nb: 0% or more and 0.3% or less, and the remainder is Fe and impurities. P, S, Ni, Cu, Al, Ca, Mg, O (oxygen), and N (nitrogen) are elements that may remain in the billet as impurities. Then, if 0≤P≤0.05%, 0≤S≤0.05%, 0≤Ni≤1.0%, 0≤Cu≤0.3%, 0≤Al≤0.3%, 0≤Ca≤0.02%, 0≤Mg≤ The ranges of 0.02%, 0≤O≤0.03%, and 0≤N≤0.05% are fully acceptable.

In the case of SKD61, by mass %, C: 0.35% to 0.42%, Si: 0.80% to 1.20%, Mn: 0.25% to 0.50%, P: 0.030% to S: 0.020 % or less, Cr: 4.80% or more and 5.50% or less, Mo: 1.00% or more and 1.50% or less, V: 0.80% or more and 1.15% or less, and the remainder is Fe and impurities.

It should be noted that, among the inner surfaces where the flow path 7 is formed, at least the parts other than the part 4 facing the melt supply port 2 may be formed of a sleeve material having the above composition. For example, as shown in FIG. 2 , all the inner surfaces of the die-casting sleeve 1 forming the flow path 7 may be composed of a member 51 having the above composition. Alternatively, the entire sleeve for die-casting can also be produced from a sleeve blank having the composition described above. Then, a part or the whole of the die-casting sleeve may be heat-treated to adjust to a predetermined hardness. For the method of this heat treatment, the above-mentioned method can be applied.

After the member 5 having the above composition is provided in the die-casting sleeve 1, the surface of the member 5 may be finished into a product shape by finishing machining or the like as necessary.

Preferably, the member 5 has a thickness of 2 mm or more in a state of being embedded in the preparation body 3 . It is more preferably 4 mm or more, still more preferably 7 mm or more, particularly preferably 10 mm or more. For such a thickness, if the member 5 is a "preformed member before installation" such as a cylindrical member or an annular member, the thickness of the annular article may be adjusted to be large. Or, in the case of "articles formed after installation" such as welded parts and sprayed parts, "multi-layer stacking" can be implemented at the time of surfacing welding and spraying.

In the die-casting sleeve 1 of the present embodiment, the surface of the member 5 forming the flow path 7 may be subjected to surface treatment. That is, the surface treatment layer 5b may be provided on the surface of the member 5 on which the flow path 7 is formed.

As the type of surface treatment, in addition to nitriding treatment, etc., homogenization treatment, physical vapor deposition method, chemical vapor deposition method, etc. can be appropriately selected. Then, as the type of the surface treatment layer 5b, in particular, a nitride layer, a nitride layer such as a nitrogen diffusion layer, an oxide layer, an oxynitride layer, a sulfur nitride layer mainly composed of sulfide and nitride, etc. Suppression of chemical melt loss is effective. These surface treatment layers may be used in combination. The thickness of the surface treatment layer is preferably not less than 0.2 mm and not more than 0.5 mm.

As an example of the above-mentioned surface treatment layer 5b, a surface treatment layer having a "nitride layer" and an "oxide layer" on the nitride layer is preferable.

More preferably, the thickness of the nitride layer is greater than 0 mm and greater than or equal to 0.2 mm. Moreover, it is more preferable to set it as 0.4 mm or less. Such a nitrided layer can be formed by, for example, various known nitriding treatments such as gas nitrocarburizing.

In addition, it is more preferable that the oxide layer is a "magnetite layer". More preferably, the thickness of the oxide layer is greater than 0 mm and greater than or equal to 0.001 mm. Moreover, it is more preferable to set it as 0.02 mm or less. Such an oxide layer can be formed, for example, by known homogenization treatment, water vapor treatment, or the like.

The above-mentioned surface treatment layer 5b is effective in suppressing chemical melting loss. Even if the molten metal strongly supplied from the molten metal supply port 2 to the flow path 7 damages the surface treatment layer 5b, the member 5 having the above-mentioned composition existing therebeneath effectively suppresses further aggravation of melting loss. Therefore, by providing the above-mentioned member 5 at the portion 4 facing the melt supply port 2 on the inner surface forming the flow path 7, and further providing the surface treatment layer 5b on the member 5, the melting resistance of the entire die-casting sleeve 1 is improved. Further improve.

The surface treatment layer 5 b may extend to the inner surface other than the portion 4 facing the melt supply port 2 among the inner surfaces forming the flow path 7 . For example, the surface treatment layer 5b may be provided on the portion where the melt supply port 2 is formed, the portion where the melt injection port 6 is formed, or the entire inner surface where the flow path 7 is formed. On the inner surface of the inner surface forming the flow path 7 other than the portion 4 facing the melt supply port 2, since the degree of occurrence of physical melting loss is low, the above-mentioned surface treatment layer 5b, which is excellent in suppressing chemical melting loss, contributes to Comprehensive improvement in melting resistance.

In the above description, the portion facing the melt supply port means at least a portion visible when the inner surface of the die-casting sleeve is viewed from the opening direction of the melt supply port 2 . Generally, the die-casting sleeve is fitted into the die-casting device in a posture in which the opening direction of the melt supply port extends substantially vertically downward. Therefore, it is preferable to install the sleeve material of the present invention, which is highly resistant to physical melting loss and chemical melting loss, at a position facing the melt supply port.

Then, in die casting, the molten metal supplied from the molten metal supply port of such a die casting sleeve may collide with a portion located approximately 45° with respect to the above-mentioned substantially vertically downward direction. Therefore, it is preferable that the sleeve blank of the present invention is also provided at the 45° position. In this case, the melt colliding with the portion located at the above-mentioned 45° also flows toward the portion facing the melt supply port, and thus the facing portion may also be melted. Therefore, if the sleeve material is provided at a portion facing the melt supply port, melting loss can be reduced.

[Example 1]

＜Production of sleeves for die casting＞

Cylindrical sleeve preparations A1 and B1 for die-casting with dimensions of approximately 200 mm in outer diameter×85 mm in inner diameter×550 mm in length were prepared. The material of die-casting sleeve preparations A1 and B1 is SKD61.

-Manufacture of die-casting sleeve A (Example)-

The inner surface of the die-casting sleeve preparation A1 was machined, and the inner diameter from the end where the plunger insertion port 8 was provided to a portion 200 mm in the longitudinal direction was set to 105 mm. Quenching and tempering was performed on the entire machined sleeve preparation A1 for die casting, and the hardness was adjusted to about 45 HRC.

On the other hand, as the member 5 provided on the inner surface of the die-casting sleeve preparation A1, a ring-shaped article (ring thickness: 10 mm) having an outer diameter of 105 mm x an inner diameter of 85 mm x a length of 200 mm was prepared. The annular article has the composition of Table 1, and the hardness is adjusted to about 53 HRC by quenching and tempering.

This ring-shaped article was thermocompression-fitted to the machined inner surface of the above-mentioned sleeve preparation A1 for die-casting. After shrink-fitting, a clamp ring is fixed to the end of the die-casting sleeve preparation A1 so that the ring-shaped article is not detached from the die-casting sleeve preparation A1.

The side surface of the sleeve preparation A1 for die-casting after thermocompression fitting of this ring-shaped article was machined, and the melt supply port 2 was provided. The melt supply port 2 is provided at a position of 60 to 160 mm in the longitudinal direction from the end portion where the plunger insertion port 8 is provided. In addition, the inner surface of the ring-shaped article after shrink fit was also machined for finishing. The configuration is such that a flow path is formed by the inner surface of the die-casting sleeve preparation A1 and the inner surface of the annular article. The external appearance of the die-casting sleeve A (or die-casting sleeves B to D described later) is shown in FIG. 3 .

The surface treatment was carried out on "all the inner surfaces" of the sleeve preparation A1 for die-casting after setting the ring-shaped article, and the sleeve A for die-casting of the Example was obtained. On the inner surface of the die-casting sleeve, a nitride layer with a thickness of about 0.3 mm is first formed by gas nitrocarburizing treatment, and then a magnetite layer with a thickness of about 0.01 mm is formed on the nitride layer by water vapor treatment. It becomes the surface treatment layer 5b.

[Table 1]

※ Contains impurities (P≤0.05%, S≤0.05%, Ni≤1.0%, Cu≤0.3%, Al≤0.3%, Ca≤0.02%

Mg≤0.02%, 0≤0.03%, N≤0.05%)

-Manufacture of die-casting sleeve B (comparative example)-

Quenching and tempering was performed on the entire die-casting bush preparation B1 to adjust the hardness to about 45 HRC. A melt supply port 2 is provided on the side surface of the die-casting sleeve preparation B. As shown in FIG. The melt supply port 2 is provided at a position 60 to 160 mm in the longitudinal direction from the end portion where the plunger insertion port 8 is provided. Then, the "all inner surfaces" of the quenched and tempered bush preparation B1 for die casting were surface-treated to prepare the bush B for die casting of the comparative example. A nitrided layer with a thickness of about 0.3 mm was formed on the inner surface of the die-casting sleeve by gas nitrocarburizing to form a surface-treated layer 5b.

<Evaluation of the melting resistance of die-casting sleeves A and B>

Sleeves A (Example) and B (Comparative Example) for die-casting were attached to an 800-t cold chamber type die-casting apparatus, and die-casting of aluminum alloy ADC12 (Fe: 1.3 mass % or less) for die-casting was performed. The temperature of the molten metal of ADC12 at the time of die casting was 680 degreeC. Then, when the number of shots (the number of die castings) reached 40,000, the inner surfaces of the two sleeves at the positions where the melt supply ports 2 were provided were observed.

The observation results of the die-casting sleeve A are shown in FIG. 4 , and the observation results of the die-casting sleeve B are shown in FIG. 5 . As shown in FIG. 4 , the surface treatment layer 5 b remained intact on the inner surface of the die-casting sleeve A, and neither chemical melting loss nor physical melting loss was observed. On the other hand, as shown in FIG. 5 , the surface treatment layer 5b was destroyed and the blank (that is, SKD61) was also worn out at the portion directly below the melt supply port 2 on the inner surface of the die-casting sleeve B. to significant melt loss.

[Example 2]

＜Production of sleeves for die casting＞

Cylindrical die-casting sleeve preparations C1 and D1 having an outer diameter of 200 mm x an inner diameter of 85 mm x a length of 550 mm were prepared. The material of the sleeve preparations C1 and D1 for die casting is SKD61.

-Manufacture of die-casting sleeve C (example of the present invention)-

The inner surface of the die-casting sleeve preparation C1 was machined, and the inner diameter from the end where the plunger insertion port 8 was provided to a portion 200 mm in the longitudinal direction was set to 95 mm.

On the other hand, as the member 5 provided on the inner surface of the die-casting sleeve preparation C1, a welding rod having the component composition shown in Table 2 was prepared. Then, by surfacing using this welding rod, two surfacing layers were formed on the machined inner surface of the sleeve preparation C for die-casting.

Then, the entire sleeve preparation C for die-casting after overlay welding was quenched and tempered so that the hardness of the SKD61 part was about 45 HRC. Thus, the hardness of the weld overlay is also about 45 HRC.

Then, the side surface of the sleeve preparation C for die-casting on which the build-up layer was formed was machined, and the melt supply port 2 was provided. The melt supply port 2 is provided at a position 60 to 160 mm in the longitudinal direction from the end portion where the plunger insertion port is provided.

The finish machining of the weld overlay was performed to set the finish thickness of the weld overlay to about 5 mm. Thus, a flow path is formed on the inner surface of the die-casting sleeve preparation C1.

The "all inner surfaces" of the die-casting sleeve preparation C1 were surface-treated to prepare the die-casting sleeve C of the example. On the inner surface of the die-casting sleeve, a nitride layer with a thickness of about 0.3 mm is first formed by gas nitrocarburizing treatment, and then a magnetite layer with a thickness of about 0.01 mm is formed on the nitride layer by water vapor treatment. It becomes the surface treatment layer 5b.

[Table 2]

※ Contains impurities (P≤0.05%, S≤0.05%, Ni≤1.0%, Cu≤0.3%, Al≤0.3%, Ca≤0.02%, Mg≤0.02%, 0≤0.03%, N≤0.05%)

-Production of die-casting sleeve D (comparative example)-

Quenching and tempering were performed on the entire die-casting sleeve preparation D1 to adjust the hardness to about 45 HRC. The melt supply port 2 is provided at a position 60 to 160 mm in the longitudinal direction from the end portion provided with the plunger insertion port 8 on the side surface of the die-casting sleeve preparation D1.

The "all inner surfaces" of the quenched and tempered bush preparation D1 for die casting were surface-treated to prepare a bush D for die casting of a comparative example. A nitrided layer with a thickness of about 0.3 mm was formed on the inner peripheral surface of the die-casting sleeve by gas nitrocarburizing to form the surface treatment layer 5b.

<Evaluation of resistance to melt erosion of die-casting sleeves C and D>

Die-casting sleeves C (Example) and D (Comparative Example) were attached to an 800 t cold chamber die-casting device, and die-casting of an aluminum alloy for die-casting (Fe: less than 0.6%) was performed. The temperature of the molten metal of the aluminum alloy during die casting was set to 720°C.

In this die-casting apparatus, the melt supplied from the melt supply port 2 is injected powerfully so as to fall to a position 45° obliquely below the melt supply port 2 . After the die casting, the inner surfaces of the two sleeves at the positions where the melt supply ports 2 were provided were observed.

FIG. 6 is a photograph of a portion 4 of the die-casting sleeve C that faces the melt supply port 2 after performing 4500 times of die-casting. In the figure, a circle indicates a position 45° obliquely below the melt supply port 2 , and a star indicates a position directly below the melt supply port 2 . As shown in FIG. 6 , for the die-casting sleeve C, at the time of 4,500 shots, the impact energy due to the molten metal is considered to be large. to physical melting loss, but the surfacing layer still remains. Immediately below the melt supply port 2, the surface treatment layer 5b remains intact, and both chemical melting loss and physical melting loss are suppressed.

FIG. 7 is a photograph of a portion 4 of the die-casting sleeve D that faces the melt supply port 2 after performing 500 times of die-casting. In the figure, a circle indicates a position 45° obliquely below the melt supply port 2 , and a star indicates a position directly below the melt supply port 2 . As shown in FIG. 7 , for the die-casting sleeve D, significant physical melting loss was observed at a position 45° obliquely below the melt supply port 2 after 500 shots. Significant chemical melting loss is also observed in the immediately lower part of 2.

[Example 3]

Assuming a material constituting the inner surface of the die-casting sleeve, the erosion resistance of the material was evaluated. Table 3 shows the component compositions of the raw materials evaluated.

[table 3]

※ Contains impurities (P≤0.05%, S≤0.05%, Ni≤1.0%, Cu≤0.3%, Al≤0.3%, Ca≤0.02%, Mg≤0.02%, 0≤0.03%, N≤0.05%)

First, blanks 1 to 4 in Table 3 were processed into the shape of a test piece 16 having the dimensions (in mm) shown in FIG. 8 . At this time, the blank 1 is a sintered product obtained by HIP (hot isostatic pressing) treatment of metal powder having the composition shown in Table 3. The hardness of the test piece 16 was blank 1:70HRC, blank 2:53HRC, blank 3:45HRC, and blank 4:45HRC.

Next, as shown in FIG. 9 , the above-mentioned test piece 16 was moved up and down at a cycle of 90 rpm and a reciprocating height of 30 mm, and a melting test was performed in which the test piece 16 was repeatedly dipped into the molten metal 17 . The molten metal 17 is an aluminum alloy AC4C (Fe: 0.5% by mass or less) specified in JIS-H-5202:2010 "Aluminum Alloy Casting", and its temperature is maintained at 700° C. by a heater 18 . The test time was set to 2 hours.

Then, based on the weight difference (that is, weight loss) of the test piece before and after the melting loss test, the melting loss rate (%) was calculated according to the following formula. The smaller the value of the melting rate, the better the chemical melting resistance. The results are shown in Table 4.

Melting loss rate (%)={(weight before test-weight after test)/weight before test}×100

[Table 4]

bad material Melting loss rate (%) 1 3 2 9 3 10 4 13

From the results in Table 4, it can be seen that the test pieces of blanks 1 to 3 have less wear and tear of the test pieces than the test piece of blank 4, and are excellent in chemical melting resistance. Moreover, the form of the physical melting loss which may arise by moving a test piece up and down was not confirmed either. Then, among the test pieces of blanks 1 to 3, the test piece of blank 1 having a composition with a C content of more than 1.0% and a large content of W, Mo, and V also had high hardness and was particularly excellent in melting resistance.

This application is based on the Japanese patent application (Japanese Patent Application No. 2016-169254) for which it applied on August 31, 2016, The content is used here as a reference.

Industrial availability

According to the present invention, it is possible to provide a sleeve for die-casting excellent in erosion resistance and a method of manufacturing the same.

Explanation of reference signs

1: Sleeve for die-casting; 2: Melt supply port; 3: Prepared body; 3a: Diameter expansion part; 3b: First opening; 4: Part opposite to the melt supply port; 5, 51: Member; 5a: 2nd opening; 5b: surface treatment layer; 6: melt injection port; 7: flow path; 8: plunger insertion port; 16: test piece; 17: molten metal; 18: heater.

Claims (2)

1. A sleeve for die casting having a flow path inside, wherein the sleeve for die casting,

a melt supply port for supplying a molten metal from the outside to the flow path penetrates from the outer surface to the inner surface of the die casting sleeve,

at least a portion of the inner surface forming the flow path facing the melt supply port is formed of a material having the following composition, in mass%, C:1.7% or more and 2.5% or less, si: less than 1.0%, mn: less than 1.0%, cr:3.5% or more and 5.0% or less of one or two of Mo and W obtained from the relation Mo+1/2W: 1.6% or more and 15.0% or less, V:6.0% or less, and further comprising at least one of Co and Nb, wherein Co: less than 10.0%, nb: less than 3.0%, the balance being Fe and impurities, and,

the blank is a sintered piece.

2. In a method for manufacturing a die-casting sleeve having a flow path inside and a melt supply port for supplying a molten metal from outside to the flow path penetrating from an outer surface to an inner surface,

preparing a preliminary body constituting the sleeve for die casting,

Providing, on an inner surface forming the flow path, at least a portion facing the melt supply port or a portion facing a portion constituting the melt supply port, a material having the following composition, in mass%, C:1.7% or more and 2.5% or less, si: less than 1.0%, mn: less than 1.0%, cr:3.5% or more and 5.0% or less of one or two of Mo and W obtained from the relation Mo+1/2W: 1.6% or more and 15.0% or less, V:6.0% or less, and further comprising at least one of Co and Nb, wherein Co: less than 10.0%, nb: less than 3.0%, the balance being Fe and impurities, and,

the blank is a sintered piece.

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