Heat treatment of stainless steel pipe fittings aims to alter their physical and mechanical properties, reduce residual stress, and restore corrosion resistance affected by previous processing. This allows for better performance of the stainless steel or enables it to withstand further high and low temperature processing. Heat treatment involves appropriate annealing, quenching, tempering, normalizing, and other related processes applied to stainless steels with different structures and types.
Based on their microstructure, stainless steel can be classified into austenitic stainless steel, martensitic stainless steel, and ferritic stainless steel. To avoid surface deformation during heat treatment, the heat treatment of these three types of stainless steel is based on their respective structures and properties.
1. Austenitic Stainless Steel Pipe Fittings
Austenitic stainless steel is the most widely used and abundant type of stainless steel. Its characteristic is an austenitic structure that does not undergo phase transformation at room temperature. It cannot be hardened by heat treatment, but can be hardened by cold working. The commonly used heat treatment method is solution treatment.
2. Ferritic Stainless Steel Pipe Fittings
Ferritic stainless steel pipe fittings typically do not undergo ν-α phase transformation, exhibiting a ferritic structure that does not transform at either high or room temperatures. However, when the steel contains a certain amount of austenite-forming elements such as carbon and nitrogen, an austenitic structure can form at high temperatures. This type of steel cannot be strengthened by heat treatment; only annealing can relieve internal stress and promote further surface treatment.
3. Martensitic stainless steel pipe fittings.
Martensitic stainless steel pipe fittings have a distinct phase transformation point. This transformation occurs at high temperatures in an austenitic structure, which then undergoes a martensitic transformation upon cooling, transforming into a martensitic structure and hardening. Because this type of stainless steel contains high levels of chromium and has good hardenability, various heat treatment methods can be used, such as quenching and tempering.
Post time: Dec-01-2025