Microstructure and properties of super martensitic stainless steel microalloyed with tungsten and copper

The microstructure and properties of super martensitic stainless steel (SMSS) microalloyed with tungsten and copper were studied by means of optical microscopy, dilatometer, X-ray diffraction and tensile tests. The results showed that the microstructure of SMSS, after quenching and tempering, was a typical biphase structure with tempered martensite and reversed austenite dispersedly distributed in the martensite matrix. W and Cu were added into the SMSS to reduce the transformation temperature (M-s) and improve the strength and hardness of the matrix by grain refining and solid solution strengthening. Thermo-Calc calculations confirmed that M23C6 compound and Laves phase were precipitated during tempering in the investigated steel. Compared with traditional SMSS, the steel microalloyed with W and Cu exhibited better mechanical properties.