The development process of Japanese hot work die steels

Hot work die steel is high strength, excellent wear resistance between the heat, alternating with resistance to thermal shock cracking of heat-resistant alloy tool steel. First as a hot work die steel hot forging die materials. Before World War II (1938) Murakami, who proposed the following ingredients for hot work die steel steel: 0.5% ~ 0.7% C steel, 0.4% ~ 0.7% C-6% ~ 12% W steel, 0.3 % ~ 0.5% C-8% ~ 12% W-2% ~ 3% Cr steel. One major use of W or W-Cr steel, steel.
JES 1947 standard to the third metal mold steel to 0.3% C-2.5% Cr-5.5% W-0.4% V steel sodium standard. The steel in 1954 as JIS SKD4, JIS standard in the new 0.3% C-2.5% Cr-9.5% W-0.4% V steel as SKD5 sodium standard.
But these Cr-W system hot work die steel excellent high temperature strength, but toughness or hardenability is low, so for the production of extrusion die casting tools or other large complex shape of the mold or mold problems. The mid-1930s, the U.S. development of H11 ~ H13 is to solve these problems of hot die steel, after the war with Japan as the rapid development of various industrial uses hot die steel. 1956 as JIS standard specifies SKD6 (AISI H11), SKD61 (AISI H13), 1972-year rule of the SKD62 (AISI H12). SKD6, SKD61 mainly used for die-casting mold, SKD62 widely used as heat between the stamping dies, extrusion dies and core rods.
After 1960, due to the rapid development of automobile industry, forging presses used as part of the progress of the production volume, better than the original SKT4 or SKD62 high life hot die steel demand increased, try a variety of steel. Including AISI H10 (0.40% C-3% Cr-3% Mo-0.3% V), AISI H10 +3% Co, AISI H19 (0.4% C-4% Cr-4% W-4% Co-2% V), AISI H23 (0.3% C-12% Cr-12% W-1% V) and so on. H19, H23 copper alloy for die-casting mold, extrusion mold.
H23 is a unique material, it does not produce martensite after quenching, quenching hardness is low around 41HRC, but with a large secondary hardening, there is a very good resistance to tempering resistance, Dongguan City, Hong Super Mold Technology Co., Ltd. Research shows that H23 is more applicable to the good material.
1983 revision of JIS standard H10 and H19 as SKD7 and SKD8 sodium standard. But with the use of more stringent conditions to change, requiring higher performance hot stamping material, gradual development of a new mold material.
Japan's leading steel hot work die steel grades: SKD4, SKD5, SKD6, SKD7, SKD8, SKD61, SKD62 and so on. Japan's Daido Steel major steel hot work die steel grades: DHA, DHA1, DH2F, DHA2, DH6, DH62, DH21, DH31-S, DH4, DH5, DH41, DH42, DH71, DH72, DH73, DH32, DH31- EX and so on.

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Source: HongChao(DongGuan)Mold & Technology Co., Ltd. Technology Center
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