ANALISIS OF MICROSTRUCTURE AND PROPERTIES OF 490 MPa HIGH STRENGTH STEEL FOR AUTOMOBILE OUTER PANEL
The microstructure and properties of 490 MPa high strength steel for automobile outer panel were analyzed by OM and tensile testing machine,and the application performance of the test steel was studied by simulation technology.The results show that the microstructure of the test steel after simulated annealing treatment is mainly the mixed structure of ferrite and island martensite,and a small amount of carbides are distributed at the grain boundary.There is no obvious yield platform in the stress-strain curve.The yield strength and tensile strength are above 300 MPa and 550 MPa,respectively.The BH(bake hardening)value is above 60 MPa under 2％pre-strain.Combined with the material properties of the test steel,taking the rear door outer panel of a vehicle as the research object,the anti-concave performance of 490 MPa high-strength steel and the anti-concave performance applied to the door outer panel were studied by simulation technology.The results show that the anti-concave stiffness of the parts decreases after high-strength thinning,but the anti-concave performance is improved to a certain extent,which meets the requirements of the anti-concave performance of the outer panel.The microstructure and mechanical properties of 490 MPa high strength steel meet the application requirements of automobile outer panel.The continuous stress-strain curve can avoid the tensile strain trace.Therefore,490 MPa high strength steel has the feasibility of application in automobile outer panel.
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