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采用不同的退火工艺对汽车车身用TRIP700钢进行热处理,然后对0.9 mm厚的TRIP700钢进行疲劳测试,并对热处理后的TRIP700钢进行显微组织分析和拉伸测试。实验结果表明:分级退火处理的TRIP700钢的残余奥氏体含量较低,具有较高的屈服应力和较低的应变硬化率;利用对数非线性拟合方程得到在应力比为0.1,加载频率为20 Hz的TRIP700钢高周疲劳S-N曲线,均匀化退火与分级退火的TRIP700钢的疲劳极限值分别是472 MPa和486 MPa。
Different annealing processes were used to heat-treat TRIP700 steel for automobile body, then fatigue test of 0.9 mm thick TRIP700 steel and microstructure analysis and tensile test of heat-treated TRIP700 steel were carried out. The experimental results show that the retained austenite content of TRIP700 steel treated by fractional annealing is lower, with higher yield stress and lower strain hardening rate. The logarithm of non-linear fitting equation is used to calculate the residual austenite content at the stress ratio of 0.1 and the loading frequency For 20 Hz TRIP700 high cycle fatigue SN curve, the fatigue limits of homogenized and fractionated annealed TRIP700 steels are 472 MPa and 486 MPa, respectively.