Study On Effects Of Q&P Treatment Processes On Microstructures And Properties Of 30cr13 Martensitic Stainless Steel

Traditional Crl3 martensitic stainless steel has its good corrosion resistance,and after quenching and tempering,it has high strength and hardness,but with low plasticity and toughness.Quenching and partitioning(Q&P)process is a new heat treatment for martensitic stainless steel that can obtain martensite and carbon-rich austenite multiphase microstructure.to improve the plasticity and toughness of steel.The study can bring a certain volume fraction of retained austenite into martensitic microstructure through quenching-partitioning.Based on 30Crl3 as tested steel,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 followed:1.The steel of 30Crl3 is annealed in the area of the carbide and ferrite,the annealing rule is:after being in the furnace at 900? for 2 hours,the steel turn cold to 500? in the furnace,and then turn cold in the air.The steel is easy to be cut and processed which brought the carbide and ferrite microstructure with 5.5HRC.2.Before Steel 30Cr13 is rolled to 1.8mm,it is required to be annealed to release the stress concentration of the hot rolled sheet,the work hardening and reduce the hardness,improve the distribution of carbide,to be convenient to the next cold rolling.The industrial annealing rules is:being heated to 900? with the furnace,keeping in the furnace for 2 hours,then cooling to the room temperature with the furnace,The annealing temperature was chose in the area of the carbide and ferrite,with a microstructure of the carbide and ferrite,and the carbide distributing dispersedly,there is a recrystallization annealing,the rules is:after 740 ? for 2 hours,cooling with the furnace.The recrystallization annealing temperature was also chose in the area of the carbide and ferrite,with a microstructure of the carbide and ferrite.3.The volume fractions of residual austenite increased monotonically with the quenching temperatures increasing in the Q&P process when the steel of 30Cr13 was austenizationed at 1080? for 1 hour subjected to partitioning at 450? for 20min after quenching to 20-60 ?.The yield strength,tensile strength,impact energy and hardness decreased with the quenching temperatures increasing in the Q&P process,but the elongation presented the extremum varitation tendency as the quenching temperature increased.The mechanical properties values of Steel 30Crl3 obtained the best coopertation of strength and plasticity as the quenching temperature was 50 ?:Hardness=44.0HRC;Rp0.2=1146MPa;Rm=1261MPa;A=16.7%;AKV=12.8J.4.The volume fraction of residual austenite and elongation presented the extrumum varitation tendency with the austenization time increasing in the Q&P process when the sheet of 30Cr13 Steel was austenizationed at 1100 ? for 6-12min subjected to partitioning at 450? for 10min after quenching to 30?.The yield strength,tensile strength and hardness decreased with the austenization time increasing in the Q&P process.The mechanical properties values of Steel Sheet 30Crl 3 obtained the best of cooperation of hardness,strength,plasticity and toughness as the austenization time is 10min:Hardness=45.1HRC;Rp0.2=1133MPa;Rm=1497MPa;A=17.4%;the volume fraction of residual.austenite is 11.4%.