Martensite stainless steel is mainly low carbon or high carbon steel, and the chromium content is between 12%- 18%. The grades of martensitic stainless steel used in different countries are as follows:
1. Low carbon and medium carbon 13% chromium steel
2. High carbon 18% chromium steel
3. Low carbon 17% chromium steel containing nickel (about 2%)
Martensite stainless steel has high strength and corrosion resistance, and can be used to manufacture turbine blades (1Cr 13), shafts and tie rods of steam equipment (2Cr 13), valves and bolts, and other parts working in corrosive media (4Cr 13). Steel grades with high carbon content (4Cr 13 and 9Cr 18) are suitable for manufacturing medical instruments, knives, measuring tools, springs, etc.
The martensitic stainless steels with extended data standards are: 403,410,414,416,416 (se), 420,430,431,440A, 440a. The corrosion resistance of these steels comes from chromium, and its range is 1 1.5 ~ 18%. The higher the chromium content, the higher the carbon content to ensure the formation of martensite during heat treatment. The above three kinds of 440 stainless steels are rarely considered as applications requiring welding, and filler metals with 440 composition are not easy to obtain.
The improvement of standard martensitic steel contains additive elements such as nickel, molybdenum and vanadium. , which is mainly used to increase the limit allowable working temperature of standard steel to above1100 K. When these elements are added, the carbon content also increases, and with the increase of carbon content, the problem of avoiding cracking in the heat affected zone of weldment hardening becomes more serious.
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