Typical Heat Treatment and Quenching Process of W18Cr4V Steel

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M23C6 begins to dissolve at 900°C and completely dissolves at 1090°C;

M6C begins to dissolve at 1037°C, and the amount of dissolution above 1250°C gradually decreases;

MC1100°C begins to dissolve, and the dissolution rate is slower than that of M6C. At 1280°C, in austenite: C 0.5%, W 7-8%, Cr 4%, V 0.6-0.8%; the total remaining K is 9-10%: among them, M6C 7.5%-9.0%, MC 1.0-1.5% .

Pic 1 Typical heat treatment and quenching process of W18Cr4V steel

Use one or two warm-ups

High-alloy high-speed steel has poor thermal conductivity. In order to prevent deformation and cracking of the workpiece during heating and shorten the heating holding time to reduce decarburization, one or two preheating is often used.

High quenching temperature

In order to make the alloy content of austenite higher, the quenching temperature should be increased as much as possible to the lower melting temperature of grain boundary (the grain is still very fine, grade 9).

Graded quenching

General oil quenching and air cooling (organization: M+Ar20- -25%+9- 10% unmelted K).

Use isothermal quenching for slender and thin pieces; (first hold in a salt bath or alkali bath for a long enough time to make the supercooled austenite isothermally transform into a lower bainite structure with high strength and toughness, and then take it out for air cooling).

In order to reduce the deformation of the workpiece, one or more staged quenching is used. For large and complex cutting tools, isothermal quenching can be used to reduce deformation and improve toughness.

Fig.2 Normal quenched structure of W18Cr4V steel

Fig.3 Overfired structure of W18Cr4V steel

Fig.4 Annealed structure of W18Cr4V steel

Staged quenching: After heating and heat preservation, the steel is rapidly cooled to a temperature slightly above Ms for two periods of time (before bainite transformation occurs) and enters the martensitic transformation zone at the speed of air cooling to carry out martensitic transformation.

Austempering: A method of heating and maintaining steel and then rapidly cooling it to a temperature slightly above Ms to transform it into lower bainite.

Double-medium quenching: After heating and maintaining the steel, it is rapidly cooled with water to the austenite metastable region below the nose tip of the isothermal transformation curve, and then transferred to oil for cooling.

Learn more:

Induction Brazing Process Method, Quality Problems And Solutions Of Woodworking Tool Carbide And Steel

The Role Of Chemical Elements In High-Speed Tool Steel

Heat Treatment Forging And Annealing Of High Speed Steel

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