Study On Effects Of Q&P Treatment Processes On Microstructures And Properties Of 30Cr13Si2 Martensitic Stainless Steel

3Cr13 martensitic stainless steel is a kind of martensitic stainless steel has a broad application prospect for its good corrosion resistance in the atmosphere,water vapor and organic acid.The traditional heat treatment process for this kind of martensitic stainless steel is quenching-tempering,which brings the steel very high strength and hardness but low plasticity and toughness.Quenching-partitioning(Q&P)process is a new heat treatment process for martensitic steel that can obtain martensite and carbon-rich austenite multiphase microstructure to improve the plasticity and toughness of the steel.With the improving heat treatment process,combining with the method of alloying will make the plasticity and toughness of martensitic stainless steel much better.Based on 30Cr13Si2 as tested steels,the influence of different Q&P heat treatment systems on microstructure and mechanical properties were investigated by using laser scanning confocal microscope(LSCM),X-ray diffraction(XRD),transmission electron microscope(TEM)and tensile testing machine.The Conclusion was obtained as follows:1.With the increase of austenitizing temperature,the dissolution of carbides in experimental steel increased,and resulted in the austenite stability improved,the temperature of martensite transformation decreased.When the austenitizing temperature is higher than that of 1050 ℃,austenite grain size grew significantly;Along with the increase of austenitizing temperature or time,quenching to the same temperature,the contents of the martensite were decreased and the contents of retained austenite increased.2.The experimental steel full austenited at 1100℃ and then subjected to partitioning at 450℃ after quenching to 20～40 ℃.Obtained the martensite matrix with the stripped inverse austenite,and the total content of austenite was about 25～30%.With the increase of the quenching temperature,the austenite content of the steel increased,the hardness and yield strength of the steel decreased,and the tensile strength,elongation,Charpy impact energy of the steel first decreased and then increased.3.The experimental steel austenited at 1100℃and then subjected to partitioning after quenching to 20℃ the microstructure and mechanical properties changed obviously with the change of the distribution conditions.In the constant distribution time 20min with the distribution temperature increased from 450℃ to 480℃,or in the constant distribution temperature 450℃ with the time extended from 20 minutes to 40 minutes,the content of austenite improved,the yield strength,tensile strength and elongation have improved in varying degrees,resulting in steel product of strength and ductility increased significantly.4.The steel of 30Cr13Si2 was austenizationed at 1100℃ for 20min subjected to partitioning at 450℃ for 40min after quenching to 20 ℃,and obtain the best strong plastic combination:Rp0.2=1373MPa,Rm=1795MPa,A=19.9%,Akv=7J,Hardness=50.6HRC;...