490MPa汽车外板用高强钢的组织性能分析

ANALISIS OF MICROSTRUCTURE AND PROPERTIES OF 490 MPa HIGH STRENGTH STEEL FOR AUTOMOBILE OUTER PANEL

采用OM和拉伸试验机等仪器分析了490 MPa级汽车外板用高强钢组织与性能,并利用仿真模拟技术对试验钢的应用性能进行了研究。结果表明,模拟退火处理后试验钢的显微组织主要为铁素体与岛状马氏体的混合组织,还有少量碳化物在晶界处分布;应力-应变曲线未出现明显的屈服平台,屈服强度与抗拉强度分别达到300 MPa和550 MPa以上,在2%预应变下BH(bake hardening)值在60 MPa以上。结合试验钢材料特性,以某车型后车门外板为研究对象,通过仿真技术研究了490 MPa级高强钢抗凹性能及应用到车门外板的抗凹性,结果显示零件高强减薄后抗凹刚度下降,但抗凹性得到一定提升,满足外板抗凹性能的要求。490 MPa高强钢的组织和力学性能满足汽车外板应用需求,连续硬化的应力-应变曲线可以避免产生拉伸应变痕,证明490 MPa高强钢具备应用于汽车外板的可行性。

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.