Hardening & Tempering
We achieve increased hardness (and therefore the strength) of steels using the vacuum hardening and tempering processes. This delivers through hardening of the material. Heat treatment processes are also used to increase fatigue life, wear resistance and, in some cases, corrosion properties. It is a tool and die heat treatment process, and is used to harden D2, to harden H13, and to harden tool steel. .
It should be noted that Hardening means to fully Through Harden a material, not surface hardening or precipitation hardening.
Hardening is carried out by heating the work to elevated temperatures (over 780°C), followed by quenching, or cooling at a controlled rate. This rapid cooling transforms the steel structure and is done for example by quenching in oil or gas. Because of the temperatures involved, there will inevitably be some degree of distortion.
After hardening, the work will be in its strongest possible condition, but unfortunately its most brittle condition. Consequently, it must be tempered. This increases the toughness whilst optimising the required hardness. It is important that this process is done within a short time after Hardening otherwise cracking may occur due to the high stresses within the part.
Most of the processes are performed in highly sophisticated furnace equipment, specially designed to give the best results possible.