Nitriding of low-carbon martensitic stainless steels 03Kh11N10M2T and 03Kh12N10MT

Abstract

1. The nitrided case on steels 03Kh11N10M2T and 03Kh12N10MT, from the surface to 50–70% of the total case depth, has high corrosion resistance in a humid atmosphere and in salt spray. 2. Tempering before nitriding, which ensures a good combination of mechanical properties of the core and the case and high stability of the structure and the dimensions during nitriding and operation, should be conducted at 580° for 10h or 640° for 4 h+580° for 10 h (steel 03Kh11N10M2T) and at 570° for 6h (steel 03Kh 12N10MT). 3. The nitrided case on steels 03Kh11N10M2T and 03Kh12N10MT does not fracture when subjected to tensile stresses as high as the proof stress of the core. 4. Retained austenite formed in steels 03Kh11N10M2T and 03Kh12N10MT during tempering and nitriding is stable at negative temperatures as low as -196° and also when subjected to tensile stress as high as the proof stress at temperatures as low as -196°. 5. After nitriding, σb=100–120 kgf/mm2 for steel 03Kh11N10M2T; with a case depth of 0.20–0.25 mm, the ductility and toughness are superior to those of widely used nitriding steels 30Kh3VA and 38KhMYuA with a case depth of 0.45 mm and it is recommended for nitrided machine parts operating at temperatures from-70 to +450°. 6. Nitrided stainless steel 03Kh12N10MT has high toughness and ductility in combination with high strength at cryogenic temperatures, and it can be recommended for nitrided machine parts operating at temperatures from -253 to +350°.