24 July 2021 Hardware Tool Steel Sheet
SKS5 Hardware Tool Steel Sheet
SKS5 is a Japanese standard alloy tool steel, corresponding to the American grade is ASTM L6 , and the supply state is soft, semi-hard, and full-hard. SKS5 is mainly used for cutting tools, impact-resistant tools; part of cold work molds. Good mechanical properties and process performance, high hardenability, adding vanadium to refine the grain of the steel, reduce overheating sensitivity, improve strength and toughness, have high fatigue strength, higher yield ratio, but poor weldability , Low plasticity due to cold deformation. It is a higher-grade spring, used as a high-load important spring with a larger section and a valve spring, piston spring, and safety valve spring with an operating temperature of <300 ℃.
SKS5 tool steel is a representative Japanese standard hot work die steel containing W. The steel is quenched at a high temperature of 1140~1150℃ and after tempering, there are P, AS9 (arsenic), S, Sb (antimony) and other elements in the crystal. Boundary segregation reduces the impact toughness and fracture toughness values of the steel, and is prone to early brittle fracture. Therefore, only repeated tempering below 400°C or tempering above 680°C can be avoided while maintaining red hardness.
SK5 tool steel adopts low temperature quenching, and the mold is not easy to be brittle. After the steel is tempered at high temperature, increasing the number of tempering and moisturizing time, or chemical heat treatment at 500~600℃ for a long time, such as nitriding treatment, will aggravate the segregation of grain boundary impurity elements.
SK5 tool steel, as the hot-rolled metal mold steel in the SKS alloy tool steel series, has high strength and hardness at high temperatures, and has good fatigue resistance against alternating cold and heat. It is widely used in die casting molds, hot extrusion, hot heading molds, and precision forging molds. It is also suitable for the production of punches and dies under high temperature and high stress but not subject to impact load. It can be used as a mold that can bear large compressive stress, bending stress and tensile stress at the same time.
Chemical Composition:
- Carbon (C): 0.85
- Manganese (Mn):0.50
- Nickel (Ni): 2.00
- Silicon (Si): 0.35
- Phosphorus (P): ≤0.030
- Sulfur (S)≤: 0.030
- Chromium (Cr): 0.50
- Copper (Cu): 0.25
Heat treatment:
Hot working specification Start temperature 1100℃, end temperature 900℃, quenching specification quenching temperature 800~850℃, hard 50HRC.
Supply status and hardness:
Annealed state, hardness ≤255HBS.
Cryogenic treatment:
In order to obtain the highest hardness and dimensional stability, the mold is immediately cryogenically cooled -70 to -80°C after quenching, kept for 3-4 hours, and then tempered. The hardness of the cryogenically processed tool or mold is 1 higher than that of conventional heat treatment. -3HRC. For parts with complex shapes and large changes in size, cryogenic treatment may cause production cracking.
Nitriding treatment:
After the mold or workpiece is nitrided, a hardened layer structure with high hardness and certain corrosion resistance is formed on the surface.