Heat Treatment of SKD61 Die Steel

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SKD61 is a Japanese brand hot working die steel, corresponding to China’s brand (GB/T 1299-2000) is 4Cr5MoSi V1, is the most widely used hot working die steel.

SKD61 features:
Vacuum degassing refining treatment of steel purity.
Spheroidizing annealing softening treatment, good cutting performance.
The strengthening elements vanadium and molybdenum are specially added, and the wear resistance is excellent.
SKD61 has good toughness and high temperature fatigue resistance, can withstand temperature fusion, suitable for long-term work at high temperature has good cutting performance and polishing performance. SKD61 is smelted in electric furnace and remelted by electroslag. The steel is cleaner and tougher. It is suitable for making small-sized steel such as aluminium, zinc, copper alloy extrusion die, die-casting die, hot forging die, and hot shearing blade (peeling, cold drawing). SKD61 is the ideal material for making top rod and headstock. It is also suitable for manufacturing high-yield plastic die. Nitriding treatment can make the surface of the die obtain good hardening layer structure, and improve the wear resistance and corrosion resistance of the extrusion die. It is very significant that the nitriding treatment of die casting die can be significantly improved, and the surface corrosion resistance is conducive to rapid demoulding of products.
SKD61 hot work die steel has beautiful metallic luster. SKD61 series products include: SKD61 pin, SKD61 pillar, SKD61 guide sleeve, SKD61 cylinder, SKD61 punch, SKD61 float pin and other precision high temperature resistant parts.
SKD61 is a medium carbon and high chromium alloy tool steel. It has high hardness and wear resistance after heat treatment. It has strong hardenability and good dimensional stability. It is suitable for making high precision and long life cold working dies and thermosetting plastic dies. It is often used to make the head.

SKD61 uses:
Thickness is not more than 2MM sheet metal, efficient blanking die, punching die and impression die.
Various scissors, inlaid blades, woodworking blades.
Thread rolling die and wear-resistant slider.
Cold heading die, thermosetting resin forming die.
Deep drawing die, cold extrusion die.
Die for automobile engine.

SKD61 performance:
SKD61 hardness
SKD61 is about HRC15-20 (HB200-230) before heat treatment.
Hardness after heat treatment: internal HRC 40 ~45, surface HV1000±100.
SKD61 has a density of 7.85g per cubic centimeter.
Hardness after TD treatment: internal HRC 40 ~45 surface HV 2500 or more.

Heat Treatment of SKD61
Quench
First stage preheating: 500-550℃
Second stage preheating: 750-800 ℃
Blow air cooling or high pressure gas cooling, etc., into the tempering furnace at 100-150℃.

tempering
Preheating: 300-350℃
Tempering Heating: 550-680℃
The air is cooled to room temperature and tempered three times. Quenching temperature 1000 ~ 1050 degrees, hardness 50 ~ 55HRC, heat treatment deformation is small, the surface can be nitrided, so that the processed products have better wear resistance.

Cryogenic treatment
In order to obtain the highest hardness and dimensional stability, the die is cryogenically cooled immediately after quenching to – 70 – 80℃ for 3 – 4 hours, and then tempered. The hardness of the cryogenically treated tool or die is 1 – 3 HRC higher than that of the conventional heat treatment. For parts with complex shape and large size change, cryogenic treatment is dangerous to crack in production.

Nitriding treatment
After nitriding, a hardened layer with high hardness and corrosion resistance is formed on the surface of the die or workpiece.

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