冷轧DP590钢的组织性能及塑性增强机理

Microstructure and formability enhancement mechanism of cold-rolled DP590 steel

采用连续退火模拟试验研究了不同退火温度和闪冷温度对DP590钢性能的影响,基于连续退火模拟结果制定了塑性增强DP590钢工业试制关键参数,对塑性增强和传统工艺生产DP590钢的力学性能及显微组织进行了分析,并探讨了其塑性增强机理。研究结果表明,随退火温度和闪冷温度提高屈服强度提高,抗拉强度呈下降趋势,传统DP590钢中马氏体主要沿铁素体晶界呈细条状或粒状分布,铁素体晶粒尺寸6~8μm,马氏体体积分数11.3%,而工艺改良后塑性增强DP590钢组织中马氏体呈弥散分布在铁素体基体内,其体积分数为8.5%,另外含有非常细小的弥散分布粒状马氏体岛或残留奥氏体,经XRD和EBSD定量分析残留奥氏体体积分数约2%,残留奥氏体对最终产品性能提高起到关键作用,且批量生产性能保持了良好的稳定性。

The continuous annealing simulator was used to investigate the influences of annealing temperature and flash cooling temperature on mechanical properties of a DP590 steel.On the basis of the simulation process above mentioned,the key process for industrial production of formability enhanced DP590 were established.The mechanical properties and microstructure of DP590 by formability enhanced and traditional process were analyzed,and the formability enhanced mechanism was discussed.The results show that as the annealing temperature and the flash cooling temperature increase,the yield strength increases and the tensile strength decreases.The martensite of traditional DP590 is mainly distributed along the ferrite grain boundary in a thin strip or granular distribution,the ferrite grain size is about 6-8μm,and the martensite fraction is 11.3%.However,the martensite of the DP590 steel with formability enhanced is dispersedly distributed in the ferrite matrix with a volume fraction of 8.5%.In addition,the formability enhanced DP590 steel contains very fine dispersed granular martensite islands or retained austenite.The fraction of retained austenite is about 2%quantified by XRD and EBSD.The retained austenite plays a key role in the improvement of the final product performance,and mass production performance has maintained good stability.