Effect Of Rolling And Heat Treatment On Microstructure And Properties Of Ferritic Stainless Steel

With the rapid development of China's national economy,stainless steel is widely used not only in military fields such as nuclear energy,national defense,aviation and ships,but also in civil industries such as transportation,kitchenware,household appliances and architectural decoration.At present,ferritic stainless steel is mainly annealed in lowtemperature bell type furnace for a long time,which has high cost and low efficiency.Due to the high carbon content of phase transformation 430 ferritic stainless steel,ferrite austenite dual phase zone will appear in high temperature annealing.The influence of annealing in dual phase zone on the microstructure and mechanical properties of cold rolling annealing is studied.However,430 LR ferritic stainless steel with low carbon content does not have dual phase zone.The rolling process is optimized to explore the effect of cross rolling on the evolution law of annealing microstructure and wrinkle resistance of cold rolling.In this paper,metallographic microscope(OM),scanning electron microscope(SEM)and electron backscatter(EBSD)were used to detect and analyze the evolution of metallographic structure and microstructure of the samples in the experiment.The research contents and results of this paper are as follows:(1)430 ferritic stainless steel hot rolled plate was heat treated at different temperatures and cooled to room temperature by quenching.The effects of heat treatment temperature on its microstructure and mechanical properties were studied.The results show that the microstructure of heat treatment quenched at 800 ? and 850 ? is ferrite grains extending along the rolling direction,and there is no martensite structure.There is martensite structure in the heat treatment quenched structure at 900 ? and above.The content of martensite first increases and then decreases with the increase of heat treatment temperature.When the annealing temperature is 950 ?,the content of martensite is the highest,and the Vickers hardness of the material will gradually increase with the increase of temperature,The annealing temperature is 1150 ? and the maximum hardness is 528.49 HV.(2)The effects of annealing temperature in dual phase zone on the cold rolling microstructure,cold rolling annealing texture and properties of 430 ferritic stainless steel were studied.The results show that after cold rolling to 0.04 mm,the cold rolling structure is composed of a large number of plastically deformed ferrite and deformed martensite.The martensite introduced during cold rolling after quenching is unevenly distributed in the parent phase,breaking the banded structure,and there are no ferrite banded grains distributed along the rolling direction in the cold rolling structure.After annealing at 950 ? for 2minutes and air cooling to room temperature,they are completely recrystallized,showing stronger {111} // ND texture,and the average grain size is 9 ?m?11 ?m.The tensile fracture of cold-rolled annealed specimen has many dimples,which is plastic fracture.(3)The effects of skew rolling angle on cold rolled annealing microstructure,texture and wrinkle resistance of 430 LR ferritic stainless steel were studied.The results show that after cold rolling to 0.4 mm,annealing at 950 ? for 30 s and air cooling to room temperature,the microstructure of the annealed plate is equiaxed ferrite grains with uniform size,complete recrystallization structure and strong {111} // ND texture.Among them,the cross rolled samples have high strength {111} <112> texture and show strong ? the recrystallization texture of the fiber is partially in the cold rolled sample along the hot rolling direction ? according to the fiber texture,the cross rolling annealed samples showed good wrinkle resistance in the tensile process.