SKD61 Tool Steel-JIS G4404

SKD61 steel belongs to hot working tool steel as per JIS G4404.

As a high-chromium alloy tool steel, SKD61 steel has high hardness and wear resistance at high temperatures after heat treatment.

SKD61 steel also has excellent machining and polishing properties, making it very suitable for making high-precision and long-life molds.

SKD61 steel is mainly supplied in annealed condition, with a hardness below 229 HBW

SKD61 STEEL CHEMICAL COMPOSITION

Grade	C	Si	Mn	P	S	Cr	Mo	V
SKD61	0.35-0.42	0.8-1.2	0.25-0.5	≤0.03	≤0.02	4.8-5.5	1.0-1.5	0.8-1.15

SKD61 STEEL RELATED STANDARD & EQUIVALENT GRADE

China/GB 1299: 4Cr5MoSiV1

USA/ASTM A681:H13

Germany/DIN 17350: 1.2344/X40CrMoV5-1

SKD61 STEEL FORGING

Initial Forging Temperature：1050-1150℃
Final Forging Temperature：>900℃
Forging Ratio：above 4:1
Post-Forging Treatment:For SKD61 steel, annealing after forging helps to eliminate internal stress, reduce hardness for processing, and also prepare for subsequent heat treatment process.

SKD61 STEEL HEAT TREATMENT

Critical Temperature for Heat Treatment of SKD61 Steel

Ac1:845℃
Ac3:870℃
Ms:270℃

Temperature Selection for Different Types of Heat treatment for SKD61 steel

Annealing:820-870℃,Cool in furnace,hardness below 229HBW
Quenching: 1020-1050℃,Oil/Air quench,quenching hardness:56-58HRC.
Tempering:560-580°C, double tempering process with hardness 50-55HRC.

SKD61 Steel Cryogenic Treatment

In order to obtain the highest hardness and dimensional stability, SKD61 steel is immediately deep-cooled at -70 to -80℃ after quenching, kept for 3-4 hours, and then tempered.

The hardness of SKD61 after deep-cryogenic treatment is 1-3HRC higher than that of conventional heat treatment. For parts with complex shapes and large dimensional changes, deep-cryogenic treatment has the risk of production cracking.

SKD61 Steel Nitriding Treatment

After nitriding treatment, the chromium-vanadium alloy in SKD61 steel is fully nitrided,forming a hardened layer with high hardness and certain corrosion resistance on the surface.The surface hardness of SKD61 steel after nitriding can reach about 70HRC.