Performance
Japanese standard with W hot die steel, the steel in the 1140 ~ 1150 ℃ high temperature quenching and the tempering after a P, AS9 (arsenic), S, Sb (antimony) and other elements in the grain boundary segregation, so that the steel impact toughness, fracture toughness value decreased, early prone to brittle fracture, it is only at the following times tempering 400 ℃ or 680 ℃ tempering above can be avoided, while maintaining red hardness.
The low-temperature quenching of steel, the mold is not easy to crack. After tempering the steel at high temperatures, increasing the number of tempering time and moisture, or 500 ~ 600 ℃ for a long time for chemical heat treatment, such as nitriding, etc., will cause the grain boundary segregation of impurity elements increased.
The steel alloy tool steel for the SKS system of hot-rolled steel metal mold at high temperatures have a high strength and hardness, resistance to hot and cold alternating good fatigue resistance [1].
Uses:
Widely used in die-casting molds for hot extrusion, hot forging die, forging die steel. Also applies to the production of high temperature, high shock load stress but is not punch, die. Available to do the same time bear a greater compressive stress, bending stress and tensile stress of the mold.
Chemical composition
Carbon C: 0.25 ~ 0.35
Si Si <0.40
Manganese Mn <0.60
P P ≤ 0.030
Sulfur S ≤ 0.020 Chromium Cr: 2.0 ~ 3.0
Vanadium V: 0.3 ~ 0.5
Tungsten W: 9.0 ~ 10.0 [2]
Heat treatment process
Starting temperature of thermal processing specifications 1100 ℃, end temperature 900 ℃, hardening specifications quenching temperature 800 ~ 850 ℃, hard-50HRC.
Supply status and annealed hardness, hardness ≤ 255HBS. [3]
Cryogenic treatment
In order to obtain the highest hardness and dimensional stability, immediately after quenching the mold in the deep cold -70 to -80 ℃, remain 3-4 hours, and then tempered by the cryogenic treatment of tool or mold hardness than conventional heat treatment hardness 1 -3HRC. Complex shape and size changes in the larger parts, cryogenic treatment has produced the risk of cracking
Nitriding
Die or workpiece by the nitrogen treatment, the surface layer with high hardness and corrosion resistance of the hardened layer of a certain organization.
