JPS6131175B2 - - Google Patents

Description

[Detailed description of the invention]

Molds for casting high-melting point metals undergo extremely large thermal shocks when pouring high-temperature molten metal, and heat cracks are likely to occur early on, and seizure and melting damage occur due to the impact of high-temperature molten metal on the mold surface. Therefore, the mold material must have high thermal conductivity, low coefficient of thermal expansion, and high resistance to melting loss to prevent excessive thermal stress, as well as appropriate high-temperature strength and sufficient toughness. Must be. Furthermore, in the case of molds for molding high-grade glass products, such as cathode ray tube molds, it is important that the mold has good demoldability and that patterns do not form. The present invention uses Ni, which has a higher thermal conductivity than Fe and is sticky, and W, Mo, WC, and Mo ₂ C powders, which have excellent thermal conductivity or melting resistance, as raw materials, and these are used to increase the final volume of Ni. After uniformly mixing to give a ratio of 96 to 14, preforming in a press or reduction treatment in vacuum or hydrogen, preforming in a press, and then HIP hot isostatic press making. Pressure-formed at a temperature below or above the melting point of Ni, it has a dense and strong structure with particularly excellent ductility, and exhibits excellent performance in the above-mentioned high-melting point metal casting applications. This makes it possible to obtain a hot mold material that exhibits particularly excellent demoldability. Table 1 shows the composition and physical properties, high-temperature hardness, small-sized Schallby impact value, and seize and wear resistance index of the material of the present invention. After uniformly mixing each powder, the sample was prepared in a vacuum.
After reduction treatment at 1050℃ x 4 hours, press molding, filling into capsules and vacuum sealing, the temperature shown in Table 1,
HIP processed under pressure conditions. Comparative material M,
N was mixed and pressed in the same way without using HIP, and then sintered in hydrogen at 1350°C for 4 hours. Comparative material O is hot work tool steel SKD61, and P is 130r, which is used for glass forming. These are melted and forged materials of stainless steel SUS420.

【table】

[Table] The material of the present invention is the conventional standard hot work tool steel SKD61.
In contrast, it can be seen that the thermal conductivity is clearly large, the coefficient of thermal expansion is small, the high temperature strength is high, and the material has excellent properties to withstand thermal shock. In addition, compared to the conventional sintered material, the HIP-finished material of the present invention has a small-sized sharpie value (expressed as 100 for the comparative sintered material M) measured at 5mmφ x 40mm (span 35mm, 2mm depth 1mmRμ notch). As is clear from the index value), it is clear that the toughness is excellent. This is because a dense structure was obtained by the HIP process, and as a result, the thermal conductivity was also
As can be seen from the comparison of N, it can be seen that an improvement effect is obtained for the sintered material. In the seizure wear test, the end face of a cylindrical sample is brought into pressure contact with a red-hot steel material at 800°C and rotated at high speed to determine the limit load that will cause seizure, and the limit load that causes seizure is determined and expressed as an index with that of comparative material M set as 100. . It can be seen that the HIP material of the present invention has superior seizure wear resistance compared to the sintered material of the same composition. This is due to its relatively high thermal conductivity. In addition, the improvement effect of seizure and wear resistance is due to WC, Mo ₂ C
The effect of carbide blending is relatively large, and the high temperature strength improvement effect is W, followed by Mo, and in terms of toughness, Mo blending is superior to W blending.
W, Mo, WC, Mo ₂ C, etc. are added singly or in combination depending on the application and requirements. Regarding the composition of material B of the present invention, HIP finishing treatment was performed without performing reduction treatment prior to HIP, but in this case, a decrease in the Shalby impact value of about 10% was observed. When HIP treatment was performed after medium reduction treatment, an effect of improving the Sialby value by about 10% was obtained. This is due to the degree of oxidation on the powder surface, and it can be seen that the products subjected to vacuum reduction and reduction in hydrogen are relatively superior in terms of toughness to those without reduction treatment. Table 2 shows the results of a heat crack test (850°C, 20°C water cooling, repeated 1000 times) for the materials of the present invention.

[Table] The test piece was a flat plate that was heated to 850°C with a flame and then cooled with water, which was repeated 1000 times. As can be seen from the comparison of BM, the material of the present invention has better heat crack resistance than the sintered material with the same composition. It also has much better heat crack resistance than hot work tool steel SKD61. This is due to the fact that the material of the present invention has a small coefficient of thermal expansion, high thermal conductivity, and appropriate high temperature strength and toughness. Table 3 shows the ratio of times until seizure occurs in a 1550°C molten metal dripping test of 13Cr steel.

[Table] The test specimen is a flat specimen tilted at 30 degrees to the horizontal plane, and while the back side is water-cooled, 5g molten metal is poured on the front surface at a height of 30 degrees.
The number of repetitions until the onset of seizure when repeatedly dropped from 100 mm is that of comparison material 0 (SKD61).
It is expressed as an index with a value of 100. The material of the present invention is a comparative 5% Cr hot work tool steel.
It can be seen that the melting and seizure resistance is much better than SKD61. This is due to the overall effect of the present invention material, such as W, Mo, WC, Mo ₂ C, etc., which have essentially excellent resistance to melting and seizure, and high thermal conductivity and roughness resistance due to sufficient bonding with Ni. It is. Table 4 shows the results of the demoldability test in molten glass molding. The test piece was a 30 mmφ x 120 cylindrical specimen (internally water cooled), which was dropped into a female mold with a concentric cylinder inner diameter of 50 mmφ x 100 mm, pressure-molded with high temperature (1050℃) glass, and then mold-cut. This is the result of reading the number of scratch patterns with a length of 1 mm or more that occurred on a 30 mm diameter cylindrical surface after repeating the test 200 times. Comparative steel P is suitable for this glass forming mold application.
(SUS420) class steel plated with Cr is generally used, but as can be seen from Table 4, the material of the present invention has significantly fewer scratch patterns and excellent demoldability than the comparative steel P plated with Cr. I can see that it is. This is Ni, W, Mo, which constitutes the material of the present invention.
This is due to the inherently excellent demoldability of WC, Mo ₂ C, etc. In the material of the present invention, if Ni exceeds 96% by volume, it will be disadvantageous in terms of overall practical performance in terms of erosion resistance and strength, and if Ni is less than 14%, it will be disadvantageous in terms of ductility. It was limited to 96-14%. Although the shrinkage rate during HIP increases, it is also possible to perform HIP finishing by omitting preliminary press molding. As described above, the material of the present invention is made of Ni, W, Mo, which has high thermal conductivity, high high-temperature strength, and small coefficient of thermal expansion, or WC, _Mo2C , which has excellent erosion resistance.
Combined with carbide and sufficiently compacted by HIP, it has strength, physical properties, erosion resistance, and toughness, and has excellent demoldability for molten glass, making it suitable for high melting point metal casting and molten glass molding. The purpose is to provide a new mold material that can be applied, provide excellent usability and longevity, and a method for manufacturing the same.

【table】

Claims (1)

[Claims] 1 Ni powder and one or more of the W, Mo, WC, and Mo ₂ C powder groups in a volume ratio such that Ni is finally 96
A tool material for high-melting point metal casting or high-temperature glass molding, characterized in that the starting materials are homogeneously mixed at ~14% and are compacted using a hot isostatic press device. 2 Ni powder and one or more of the W, Mo, WC, and Mo ₂ C powder groups in a volume ratio of 96
Mix uniformly to ~14%, preform with a press, put it in a capsule, vacuum the inside, seal it, use a hot isostatic press device, and press at a temperature of 980.
A method for producing a tool material for high-melting point metal casting or high-temperature glass molding, which is produced by pressurizing at ~1450°C. 3 Ni powder W, Mo, WC, one of the _Mo2C powder group
The volume ratio of the species or two or more species is finally 96 ~
After mixing uniformly to 14%, it is reduced by heating in vacuum or hydrogen, preformed in a press, placed in a capsule, evacuated inside, sealed, and hot-static. A method for manufacturing a tool material for high-melting point metal casting or high-temperature glass molding, characterized in that the manufacturing method uses a hydraulic press device and pressurizes at a temperature of 980 to 1450°C.