On 2018-08-08 14:48:54
Why do stainless steel forgings need heat treatment after forging?
Why do stainless steel forgings need heat treatment after forging? The purpose of heat treatment for stainless steel forgings after forging is to refine the coarse grains caused during forging, eliminate work hardening and residual stress, reduce hardness, improve machining performance, prevent white spots in forgings, ensure the required metal structure and mechanical properties, and prepare for final heat treatment.
According to the experience of the manufacturer for many years, there are 6 commonly used heat treatment methods:
1. Complete annealing - eliminate the coarse inhomogeneous structure and widmanstatten structure in the forging process, refine the grain, eliminate the residual stress and reduce the hardness of the forging.
2. Spheroidizing annealing - to obtain spheroidal cementite and ferrite structure, which not only reduces the hardness, but also is easy to obtain a smooth machined surface during machining, and is not easy to produce deformation cracks during subsequent quenching. (Shanxi CITIC Heavy Industry Forging Co., Ltd. specializes in producing all kinds of hot forging, cold extrusion and cold drawing parts)
3. Isothermal annealing - can not only shorten the annealing time, but also get uniform structure and reduce the hardness. In important forgings, it can also be used to diffuse hydrogen and prevent white spots. Annealing process is generally used in the heat treatment of aluminum alloy and copper alloy after forging. The purpose is to eliminate work hardening, stress and improve plasticity.
4. Normalizing can obtain fine pearlite, which can improve the mechanical properties of forgings and is suitable for machining.
5. Normalizing and high temperature tempering - eliminate the stress produced during normalizing cooling, improve plasticity and toughness.
6. Quenched and tempered forgings have good comprehensive mechanical properties.
These are the reasons why the stainless steel forgings should be heat treated after forging.