Quench & Temper

Quench and Temper can also be referred to as Neutral, Martensitic, or Through Hardening. Time at heat and temperature are critical in the hardening transformation phase. Rapid cooling and tempering complete the process.

Quench & Temper
line

Quench and Temper provides strength and uniformity of hardness "through" the entire part from the surface to the core. This is achieved by heating the entire part up above the transformation temperature for a set period of time. Upon quenching, parts must be tempered to the desired hardness creating a Tempered Martensitic Microstructure.

Medium Carbon Steels (.25-.70C) are commonly Quench and Tempered. During this quenching process, parts are cooled rapidly thereby locking in the microstructure transformation. Oil is a very common quench medium for this process. In some applications, such as thicker materials or lower Carbon steel, water is used as a quench medium, which results in a greater uniformity of hardness. When properly Quench and Tempered, the result will yield a Martensitic Microstructure.

Tempering of quenched steel is the critical final stage of the process. Residual stress from the change in Microstructure causes spontaneous cracking if it is not relieved. Tempering is the reheating of a part to relieve those stresses that have formed and to bring the hardness down to the desired end hardness. Parts with a low Rockwell Hardness may require longer time at temperature with higher heat.