Martensitic stainless steels
Technical data sheets for martensitic stainless steel grades
Definition and applications
Martensitic steels is the smallest family of commercially available stainless steels. Martensitic stainless steel has excellent mechanical properties and is easy to process. Martensitic steel is the only stainless steel that can be subjected to hardening and heat treatment in order to improve its mechanical properties (tensile strength, yield strength and hardness). These steels are used in applications where is required abrasion resistance and hardness (surgical instruments, industrial blades, coating plates, pump components, valve parts, turbine blades, etc.). Martensitic steel is less ductile and with smaller notch strength ratio than ferritic, austenitic and duplex steels. Although many martensitic stainless steels can be welded, preheating and post-welding heat treatments are required. However, these treatments limit martensitic steel from use in welded structures.
Stainless steels are characterized by chromium in variable percentages between 11÷18% and with carbon contents, ranging from low values (0.08%) up to considerable levels (1.20%). Some of these steels contain nickel, but in much lower percentages than the austenitic types (2.5% max).
Due to the high carbon contents, unlike austenitic and ferritic steels, martensitic stainless steels have phase transformation and it is therefore possible to carry out the hardening heat treatment on them, which is useful for improving the mechanical properties, in particular hardness, tensile and yield strength. After quenching, the structure obtained, depending on the carbon content, is martensite or martensite plus carbides. If the final product must be resistant to low temperature, hardening, stress relieving or tempering are required.