JPS6149378B2 - - Google Patents

Description

[Detailed description of the invention]

This invention has excellent wear resistance, plastic deformation resistance, oxidation resistance, thermal shock resistance, and corrosion resistance, and is particularly applicable to molds in die casting machines and other directly molten metals that require these properties. Sleeves, cylinders, plungers, extrusion pins,
Furthermore, the present invention relates to a cermet suitable for use in manufacturing members such as cores (hereinafter collectively referred to as die casting mold members). In general, the die casting method is used to produce castings of Zn, Mg, Al, Cu, and alloys thereof because it can produce castings with high productivity and high dimensional accuracy. Furthermore, in recent years, research into die casting of steel materials having a higher melting point than these materials has been actively conducted. When die-casting steel materials, the casting temperature is higher than 1300°C, so die-casting mold parts have excellent wear resistance, plastic deformation resistance, oxidation resistance, thermal shock resistance, and corrosion resistance. It is required to have the following. However, when a steel material is die-cast using a JIS-SKD-61 die-casting mold member that is normally used for die-casting Al and Al alloys, the die-casting member has insufficient properties as a whole. Therefore, the lifespan is a few hundred shots at most, and even if you use a Mo-based alloy or a W-based alloy that is more heat resistant, these alloys will not last. Because it lacks wear resistance, plastic deformation resistance, and oxidation resistance, it is limited to about 5,000 shots, and currently does not have a fully satisfactory service life. Therefore, from the above-mentioned viewpoint, the present inventors have developed an excellent material that can be used as a die-casting mold member when die-casting not only Zn, Mg, Al, Cu, and their alloys, but also steel materials. As a result of research to develop a material that exhibits a long service life, we found that a composite carbonitride solid solution of Ti and W (hereinafter referred to as (Ti, W) CN): 1 to 10
%, also as dispersed phase forming components, Mg, Zr, Al,
Y, and Hf oxides (hereinafter referred to as MgO and Hf, respectively)
ZrO ₂ , Al ₂ O ₃ , Y ₂ O ₃ and HfO ₂ , collectively referred to as metal oxides): 0.05 to 2%; Accordingly, all of them contain one or two of the following as bonding phase forming components: Mo: 1 to 10%, Cr: 1 to 10%, and the rest is W and inevitable impurities as bonding phase forming components. In cermets having a composition of A further improvement in oxidation resistance was observed, and the binder phase W ensured excellent thermal shock resistance and corrosion resistance, and Cr
The oxidation resistance of the binder phase is further improved by the addition of Mo, and the thermal shock resistance of the binder phase is further improved by the addition of Mo. It has excellent wear resistance, plastic deformation resistance, oxidation resistance, thermal shock resistance, and corrosion resistance, and therefore, when put into practical use, it exhibits extremely excellent performance. They have found that it can be used for an extremely long period of time. This invention was made based on the above knowledge, and the reason why the component composition was limited as described above will be explained below. (a) (Ti, W)CN This component has the effect of accelerating the sintering of W during sintering and densifying the cermet, and also forms a dispersed phase to improve the wear resistance of the cermet. , has the effect of improving plastic deformation resistance and oxidation resistance, but if its content is less than 1%, the desired effects cannot be obtained, while if it is contained in excess of 10%, thermal shock resistance The content was determined to be 1 to 10% because it causes deterioration. (b) Metal oxides These components have the effect of suppressing the grain growth of W during sintering, and also have the effect of forming a dispersed phase to further improve the oxidation resistance of the cermet.
If the content is less than 0.05%, the desired effect cannot be obtained, while if the content exceeds 2%,
Since the toughness of cermet tends to decrease, its content is set at 0.05 to 2%. (c) Cr Since the Cr component has the effect of improving the oxidation resistance of the binder phase, it is included as necessary, but if the content is less than 1%, the desired effect of improving oxidation resistance cannot be obtained. On the other hand, if the content exceeds 10%, the thermal shock resistance deteriorates, so the content was set at 1 to 10%. (d) Mo The Mo component has the effect of improving the thermal shock resistance of the binder phase, so it is included as necessary, but if the content is less than 1%, the desired effect of improving thermal shock resistance cannot be obtained. , on the other hand, if it is contained in excess of 10%,
The content was set at 1 to 10% since the corrosion resistance deteriorates. Next, the cermet for die-casting mold members of the present invention will be specifically explained with reference to Examples. Example As raw material powder, all commercially available average 1.5 μm
(Ti,W)CN powder with 0.15μm
MgO powder, 1.0 μm ZrO ₂ powder, 0.3 μm
Y ₂ O ₃ powder, 0.3 μm Al ₂ O ₃ powder, 0.2 μm
HfO ₂ powder, 1.5μm W powder, 3.5μm Cr
Powder and Mo powder of 0.5 μm were prepared, and these raw powders were blended into the composition shown in Table 1, wet-pulverized and mixed in a ball mill for 72 hours, and then press-molded into a green compact. 100 powder compacts
By sintering in a nitrogen atmosphere with a predetermined pressure in the range of ~760 torr at a temperature of 2000°C for 1 hour, it has a composition that is substantially the same as the blended composition, and a diameter of: Cermet members 1 to 12 of the present invention having dimensions of 20 mmφ x length: 100 mm were manufactured. In addition, for comparison purposes, the materials are made of SKD-61, which is known as a conventional material, and made of W-based alloy (W-2% Mo).
-4%Ni-2%Fe) and Mo-based alloy (Mo-
0.7%Ti-0.2%Zr) and having the same dimensions were prepared as conventional members 1 to 3. Next, these cermet members 1 to 12 of the present invention
And for conventional members 1 to 3, room temperature and 600
The Vickers hardness at ℃ was measured, and this was used as a mold core of a die-casting machine and assembled into a mold cavity. C: 3.5%, Si:

[Table] 2.1%, Mn: 0.8%, p: 0.1%, S: 0.05%, Fe
and other unavoidable impurities: The molten cast iron consisting of the remainder was cast at a molten metal temperature of 1380°C, and an automobile iron casting (valve blocker arm) was die-cast, and the number of shots until the service life of the mold core was calculated. It was measured. The service life of the mold core was defined as the point in time when at least one of the cast surface roughness and dimensional accuracy in the core forming part of the cast iron casting exceeded the allowable value. These results are also shown in Table 1. From the results shown in Table 1, it is clear that all of the cermet members 1 to 12 of the present invention exhibit significantly superior service life compared to conventional members. As mentioned above, the cermet of the present invention has excellent wear resistance, plastic deformation resistance, oxidation resistance, thermal shock resistance, and corrosion resistance, so it can be used as a die casting mold member that requires these properties. When used, it exhibits excellent performance over an extremely long period of time.

Claims (1)

[Claims] 1. 1 to 10% of a composite carbonitride solid solution of Ti and W as dispersed phase forming components, Mg, Zr, Al,
One or more of the oxides of Y and Hf: 0.05 to 2%, and the remainder is W as a binder phase forming component and unavoidable impurities (wt%). Characteristic cermet for die casting mold parts. 2. Composite carbonitride solid solution of Ti and W: 1 to 10% as dispersed phase forming components, Mg, Zr, Al,
Contains 0.05 to 2% of one or more of the oxides of Y and Hf, further contains 1 to 10% of Mo as a bonding phase forming component, and the remainder is a bonding phase forming component. A cermet for die-casting mold members, characterized by having a composition (the above weight %) consisting of W as a component and unavoidable impurities. 3. Composite carbonitride solid solution of Ti and W: 1 to 10% as dispersed phase forming components, Mg, Zr, Al,
Contains 0.05 to 2% of one or more of the oxides of Y and Hf, and further contains 1 to 10% of Cr as a bonding phase forming component, with the remainder forming a bonding phase. A cermet for die-casting mold members, characterized by having a composition (the above weight %) consisting of W as a component and unavoidable impurities. 4. Composite carbonitride solid solution of Ti and W: 1 to 10% as dispersed phase forming components, Mg, Zr, Al,
Contains one or more of Y and Hf oxides: 0.05 to 2%, and further includes Mo: 1 to 10%, Cr: 1 to 10%, both as bond phase forming components. 1. A cermet for die-casting mold members, characterized in that it has a composition (the above weight %) comprising W as a binder phase forming component and unavoidable impurities.