Martensitic monocarbide stainless steel: The carbon content of the co-precipitation point of Fe-C alloy is 0.83%. In stainless steel, the S point is shifted to the left due to chromium, stainless steel containing 12% chromium and more than 0.4% carbon, and stainless steel containing 18% % chromium and more than 0.3% carbon stainless steel are hypereutectoid steels.
This type of stainless steel is heated at the normal quenching temperature, and the secondary carbides cannot be completely dissolved in austenite, so the structure after quenching is composed of martensite and carbides. There are not many stainless steel grades in this category, but some stainless steels with relatively high carbon content, such as 4Cr13, 9Cr18, 9Cr18Mov, 9Cr17MoVCo steel, etc., the 3Cr13 steel with the upper limit of carbon content is quenched at a lower temperature, and may also appear such an organization.
Due to the high carbon content, although the above three steel grades such as 9Cr18 contain more chromium, their corrosion resistance is only comparable to that of stainless steel containing 12~14% germanium. The main uses of this type of stainless steel are parts that require high hardness and wear resistance, such as cutting tools, bearings, springs and medical equipment.
