Explanation

For stainless steel with chromium content no less than 12% (generally between 12% and 18%) and martensite structure at room temperature, 13% chromium content of stainless steel can form austenite when heated. Because chromium significantly improves hardenabilhy, martensitic transformation will occur even after air cooling at high temperature to obtain martensite structure. martensitic stainless steel has higher carbon content than ferritic stainless steel. With the increase of carbon content, its strength, hardness, wear resistance and machinability are significantly improved, but its corrosion resistance is reduced. To improve corrosion resistance, a certain amount of elements such as nickel, molybdenum, and copper can be added; To improve cutting performance, easy cutting elements such as sulfur, lead, selenium, and tellurium can be added. martensitic stainless steel has high strength and hardness, but its plasticity and toughness are worse than those of austenitic and ferritic stainless steel. It has ferromagnetism, and can be hardened by air cooling, so its weld performance is poor, so it is generally not suitable for weld. Cr13 martensitic stainless steel is mainly used for components or parts with high requirements for mechanical properties but low requirements for corrosion resistance. The strength and hardness increased with the increase of carbon content, but the corrosion resistance decreased. Crl7Ni2 martensitic stainless steel with high chromium content and nickel addition has comprehensive properties of good combination of corrosion resistance, strength and toughness, and is widely used in parts with high requirements for mechanical properties and corrosion resistance in petroleum, chemical and aviation industries.

Classification