| Super martensitic stainless steel with higher strength, toughness, good cavitation and water erosion resistance and weldability are increasingly applied inconstruction of nuclear power engineering, large turbine, high pressure feed water pump and oil country tubular goods. With the super martensitic stainless steel use continues to expand, the strength and the corrosion resistance requirements are also rising. This paper intends to introduce carbon steel quenching-the latest incomposition and process design of super martensitic stainless steel in thepartition (Q&P) technology and nitrogen alloy, greatly enhance the strength and corrosion resistance.This paper use the existing commercial super martensitic stainless steel 00Cr13Ni5Mo and N alloy special design to melting of super martensitic stainless steel 06Crl3Ni5MoN as the object of study, the effects of different Q&P heat treatment system on phase composition and the content, distribution and morphology of retained austenite were investigated by charactering the tested steel samples using laser scanning confocal microscope (LSCM), scanning and transmission electron microscope (SEM and TEM) and X-ray diffraction (XRD). The influence of different Q&P heat treatment system on mechanical properties and corrosion resistance of tested steel was examined by conducting tensile, Chary impact and electron chemical polarization tests. Finally, one heat treatment system which can synthetically improve the mechanical properties and corrosion resistance of super martensitic stainless steel was found. The conclusion was obtained as follows:1.Quenching suspension temperature significantly affected the yield strength of Q&P martensitic stainless steel, austenitic extreme temperature minimum yield strength; quenching suspension temperature on the tensile strength of less affected, but still appear minima in austenite of extreme temperature. The quenching suspension temperature is lower than the extreme temperature of austenite can get the best strength and plasticity; When quenching to suspend the temperature higher than austenitic temperature extremum, can lead to secondary martensite appear in the organization, serious damage to plastic toughness.2. When the commercialize super martensitic stainless steel 00Cr13Ni5Mo use the Q&P process, Retained austenite volume fraction of extreme temperature range of 120-140 ℃, But due to the interstitial C and N in steel cap, the retained austenite content is not very more generally in the range of 5%～10%. The commercialize super martensitic stainless steel 00Cr13Ni5Mo through the Q&P process, plastic toughness quite with 00Cr13Ni5Mo through the Q&T process, but the tensile strength increased significantly, more than 1100 MPa can be achieved, Solve the problem of the super strength of martensite stainless steel is lower than the low carbon martensite stainless steel.3.Specially designed for Q&P process of super martensitic stainless steel 06Cr13Ni5MoN improves the gap element content of C N, through the appropriate Q&P process can obtain 20%～25% of the retained austenite, than traditional super martensitic stainless steel Q&P process of retained austenite content in more than 2 times higher. 06Cr13Ni5MoN after dealing with the Q&P steel tensile strength up to 1300 MPa, elongation up to 24%,impact work up to 100 J. Q&P process is very good to improve the comprehensive mechanics performance of the super martensitic stainless steel.4.06Cr13Ni5MoN through Q&P process, electrochemical corrosion performance was obviously improved compared with 00Cr13Ni5Mo through Q&P process, The pitting potential of Steel 06Cr13Ni5MoN quenched to 80℃ and partitioned at 450℃ for 1h after austenitied at 1000℃ for 1h was highest (485mV) which is higher than 00Cr13Ni5Mo through Q&P process, only have 125mV, Containing N super martensitic stainless steel corrosion resistance had the very big enhancement. |
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