M Martensitic Chromium Stainless Steel 4Cr13
Martensitic Chromium stainless steel 4Cr13 (Old designation 420) is a general-purpose martensitic stainless steel with medium Carbon, low-medium Chromium content, and good corrosion resistance. It contains more Carbon than the ferritic series and is commonly used in knives and Cuter Tools. The strength and hardness of 4Cr13 stainless steel is somewhat lower than the most common martensitic stainless steel in the AISI 440 series.
Martensitic stainless steel 4Cr13 is the most widely used stainless steel for cold work because of its excellent hardenability, toughness, low cost and formability. It is capable of being hardened from a relatively low Austenitising temperature and can reach a hardness of up to 55 HRC when Heat Treated. It has good corrosion resistance in non-oxidizing acids and a great resistance to corrosion in alkaline Chlorides.
4Cr13 has twice the strength of Carbon Steel and is widely used for making knives and cutting tools. It is also used for making parts that must be hardened and tempered after forming, such as Gears, Shafts and Bearings.
Mechanical properties:
The mechanical properties of 4Cr13 stainless steel depend on the alloy composition and variety of heat treatments. It is usually supplied in the annealed state, but it can also be oil-quenched and tempered for higher hardness and strength.
Tensile Strength: 800 - 1000 MPa
Yield Strength: 500 - 700 MPa
Elongation: 5 - 20 %
Hardness: 30 - 55 HRC
At room temperature, 4Cr13 has a yield strength of 500 - 700 MPa, tensile strength of 800 - 1000 MPa and a hardness of 30 - 55 HRC. It has good toughness and ductility, with an elongation of 5 - 20%. It arrives in the annealed condition, but it can be heat treated to increase strength and hardness. After heating, its tensile and yield strengths are comparable to those of other martensitic grades, such as AISI 420 and AISI 440.
Factors affecting the mechanical properties of 4Cr13 include heat treating procedure, microstructure, and alloying elements. It is important to note that the addition of large amounts of alloying elements may reduce the toughness of the material, even if it initially increases its strength.
Corrosion resistance:
4Cr13 stainless steel has good corrosion resistance in non-oxidizing acids. It is especially resistant to Alkaline Chlorides, which is an important consideration for knives and cutlery. When exposed to chlorides at temperatures below 60°C (140°F), 4Cr13 maintains a high resistance to pitting and crevice corrosion.
Applications:
4Cr13 is used for making knives and cutting tools, as well as parts that require heat treating after forming, such as Gears, Shafts and Bearings. Its low cost and good corrosion resistance make it attractive for applications that do not require high mechanical properties.
Conclusion:
Martensitic Chromium stainless steel 4Cr13 (Old designation 420) is a general-purpose martensitic stainless steel with medium Carbon and low-medium Chromium content. It is capable of being hardened from a relatively low Austenitising temperature and can reach a hardness of up to 55 HRC when Heat Treated. It has excellent corrosion resistance in non-oxidizing acids and is especially resistant to Alkaline Chlorides. 4Cr13 is used for making knives and cutting tools and for making hardened parts such as Gears, Shafts and Bearings. Its low cost and good corrosion resistance make it attractive for applications that do not require high mechanical properties.
