Heat treatment of precipitation hardening stainless steel forgings
Dec. 08, 2020
The company's stainless steel forgings include stainless steel elbows, tees, flanges and so on. During the production process, the heat treatment of the stainless steel forgings may cause precipitation hardening reaction. This phenomenon is explained again.
The matrix of precipitation hardening stainless steel forgings is austenite or martensite structure, and can be hardened by precipitation hardening (also known as age hardening). Since precipitation hardening stainless steel forgings have both the corrosion resistance of austenitic stainless steel and the high strength of martensitic stainless steel, the hardness of precipitation hardening stainless steel is not high after solution treatment, so it can be cut and then improved by aging Strength and hardness. Due to the low aging temperature and small heat treatment deformation, the precision and complex parts that work in the corrosive medium environment are mostly made of precipitation hardening stainless steel.
The heat treatment process of precipitation hardening stainless steel forgings is generally divided into two steps:
First, the forging blank is solid solution treated, that is, the precipitation hardening stainless steel forging blank is heated to the solid solution temperature to dissolve various elements in the austenite. After the austenitization is completed, the water (oil) cooling or air cooling is performed. The metallographic structure after solution treatment is generally austenite or low-carbon martensite, with low hardness, which is convenient for machining. After the forging is formed, precipitation hardening (age hardening) is carried out, that is, aging is used to produce fine and dispersed precipitation phases to obtain the highest possible strength and good comprehensive mechanical properties. Generally speaking, the aging temperature and time of precipitation hardening stainless steel forgings are selected according to the hardness and strength requirements of the forgings.
The precipitation hardening stainless steel forgings of solution treatment are generally blanks, so the oxidation and corrosion of the surface of the parts do not need to be considered during solution treatment, and they can be heated in a box-type electric furnace. If the temperature of the ordinary electric furnace cannot reach the solid solution temperature, it can also be heated in a salt bath, and the oxide layer on the surface of the blank can be removed after solution treatment. When aging treatment, it is already processed and formed forgings and must be carried out in a furnace with a protective atmosphere, preferably in a vacuum electric furnace to prevent oxidation of the surface of precipitation hardening stainless steel forgings.
Therefore, our company will effectively deal with forging stainless steel flanges.