Fast Track Service of Alpha Detroit: How to Process Water, Oil and Air Hardening Tool Steels?

07 February 2023

Heat treatment is a crucial process that manufacturers carry out in altering the properties of metal workpieces. It often features various industrial, thermal, and metalworking techniques to change the characteristics of materials. These techniques include quenching, tempering, annealing, hardening, and stress relieving.

With the right heat treatment techniques, manufacturers can expect improvements in the strength, hardness, ductility, toughness, and elasticity of their metal parts and products. They can even use these techniques to process glass and other similar materials.

But one particular type of metal that should be subjected to various heat treatment techniques is tool steels. They should undergo the right heat treatment techniques so they can boast great toughness, wear resistance, and heat resistance. Various types of tool steels must be heat treated carefully. Some of them are as follows.

Water Hardening Tool Steels

Water hardening tool steels often contain around 1% carbon and a tiny amount of vanadium for toughness and grain refining. When processing these materials, their depth of hardening should be around 3mm when quenched from a normal hardening temperature of 780°C. The hardening depth can then be increased to around 6mm when quenching at 870°C. As the quench temperature increases, their toughness will decrease.

When quenching water hardening tool steels, one may use cold water or 10% brine solution to reach their maximum hardness. Vigorous agitation is likewise needed to reach satisfactory quenching since a slow cooling rate can cause the formation of soft spots. Tempering these tool steels must then be carried out in the range of 150 to 250°C to attain the needed hardness.

These materials are often used in woodworking tools and cold-heading tools.

Oil Hardening Tool Steels

Oil hardening tool steels, alternatively, are materials that have been hardened from 800 to 840°C by quenching them into the oil. When heat treating these materials, they should be preheated first at 650 to 700°C. Doing this allows them to equalise at a subcritical temperature before raising them to their austenitisation temperature, making sure that they retain dimensional stability throughout their applications.

When tempering oil hardening tool steels, manufacturers should expose them to temperatures of 170 to 200°C. Their exposure to these temperatures can provide them with hardness over 60HRc. Once they are tempered in the range of 250 to 350°C, their impact strength can be significantly reduced, making them weak against external forces.

Oil hardening tool steels are perfect for heavy section punches than the W series tool steels as they possess good dimensional stability.

Air Hardening Tool Steels

Air hardening tool steels, ultimately, are tool steels with grades W and D of AS1239. They need to be preheated at 780°C before they undergo austenitising and hardening as they may be affected by still air cooling. Large sections of these tools may likewise need to be cooled in an air blast so they can attain maximum hardness.

These tool steels should be tempered when cooled to a handwarm condition. They may also require multiple tempering processes so they can transform and achieve maximum toughness.

If you need to acquire some heat-treated tool steels, you can contact us at Alpha Detroit Heat Treatment. We pride ourselves on providing quality service and reliability, especially in terms of your heat treatment needs.

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