One  Annealing

1. Full Annealing and Isothermal Annealing

Full annealing also known as re-crystallization annealing is generally referred to as annealing. It is mainly used on various carbon and alloy steel casting, forging and hot-rolled profiles of sub-eutectoid composition and sometimes on welded structures. Usually it is used as the final thermal treatment for some light-weighted work-pieces or pre-heat treatment for some work-pieces.

2.  Spheroidizing Annealing

Spheroidizing annealing is mainly used on hypereutectoid carbon steel and alloy tool steel (such as steel used to manufacture cutting tools, measuring tools and molds). Its main purpose is to reduce the hardness to improve machinability and prepare for the subsequent quenching.

3. Stress Relief Annealing

Stress relief annealing is also known as low-temperature annealing (or high-temperature tempering), which is mainly used to eliminate residual stress on casting, forging, welding, hot-rolled, cold-drawn pieces and the like, otherwise such stress will cause deformation or cracks on these steel work-pieces after a certain period of time or in subsequent machining process.

Two  Quenching

The most commonly used cooling medium is brine, water and oil. The work-pieces with brine quenching can obtain high hardness and a smooth surface, without prone to soft spot that are not quenched hard. However, it makes the work-pieces easily deformed and even cracked. While oil used as quenching medium only applies to quenching for some small-sized carbon steel work-pieces or overcooling austenite alloy steel with relatively better stability.