DP980冷轧高强钢连续退火工艺及强韧性行为研究

采用连续退火模拟试验机研究了连续退火工艺中缓冷及过时效温度对DP980冷轧高强钢组织性能的影响规律,并利用扫描电镜、透射电镜及拉伸试验机进行了显微组织及力学性能检测。研究结果表明:缓冷温度降低有利于新生铁素体及富碳岛状马氏体的生成,且实验钢屈服强度基本不变,抗拉强度先下降后升高,伸长率逐渐上升。缓冷温度为650℃时,强塑积(PSE)达到最大值15.55GPa·%。随着过时效温度的升高,实验钢抗拉强度及屈服强度略有下降,断后伸长率显著升高。工业试制HC550/980DP成品的屈服强度不小于570 MPa,抗拉强度不小于1 080 MPa,伸长率不小于7%,达到应用标准。

Investigation on continuous annealing process and strength- toughness behavior of high strength cold rolled DP980 steel

The continuous annealing simulator was used to investigate the influences of slow cooling and over- aging temperature on microstructure and mechanical properties of a high strength cold rolled DP980 steel during continuous annealing process.The microstructures were observed by scanning electron microscopy and transmission electron microscopy.The mechanical properties were measured by uniaxial tensile tests.The research results revealed that reducing the slow cooling temperature could contribute to the generation of new ferrite and island- like martensite.At the same time,the yield strength remained stably while the tensile strength decreased firstly then increased and the elongation enhanced.The maximum PSE (15.55 GPa·%) could be obtained at the slow cooling temperature of 650 ℃.The yield and tensile strength reduced gradually with the over- aging temperature increased.Meanwhile,the total elongation had a significant increase.Industrial trial production of HC550/980DP with yield strength more than 570 MPa,tensile strength more than 1 080 MPa and elongation more than 7% was obtained,which has already reached the application standard.