Research On Heat-treatment And Properities Of A New Type Of Nitrogen Contained Martensitic Stainless Steel

The performances of martensitic stainless steel can be adjusted by annealing, quenching and tempering. It has good machinability, and high strength, high hardness and corrosion resistance of certain after heat treatment. Martensitic stainless steel is commonly used in the manufacture of turbine blades, bolts, measuring tools, cutting tools, medical equipments, etc. For the purpose tool, the knife has the best cutting performance when it reaches the peak of the hardness of58HRC. This is also primary condition of the selection of high-grade tool maerial. Traditionally stainless steel used as cutting tools mainly obtains high hardness by increasing carbon content, and improves corrosion resistance by adding more chromium, molybdenum and othe noble metals. This process increases the manufacturing cost of the tool. Increasing the nitrogen content of stainless steel can improve its strength and corrosion resistance and save the expensive nickel resources. In this paper, a new type of nitrogen contained martensitic stainless steel M3is designed by thermodynamic calculation results. And heat treatment and cold rolling process of the steel are studied. The conclusions are as follows:The range of chemical composition of Cr15MoN is:C0.30～0.35, Si<0.60, Mn0.80～1.50, P≤0.030, S≤0.010, Cr14.50～15.50, Mo0.60～1.00, N0.08～0.133。Cr15MoN has good high temperature plastic, and its thermal expansion coefficient is similar to444J1steel. It is suitable for rolling production; its heating temperature is1230℃, the final rolling temperature of980℃. Annealing temperature can be set at840～880℃, and prolonged annealing favorable for homogeneous microstructure. M3reaches its highest hardness of58HRC and good corrosion resistance when normalized at1100℃. Tempering temperature of M3should be lower than300℃because the secondary hardening is obvious when tempering at300～50O℃.The corrosion resistance decreases when tempering temperature exceeds400℃. Cold rolling resistance of M3is similar to and3Cr14N, and annealing temperature of M3can be set at780～820℃.