连退工艺对DP780高强汽车钢组织性能的影响

Effect of continuous annealing process on microstructure and properties of DP780 high strength automobile steel

为制定DP780高强汽车钢合理的生产工艺,对其进行了连续退火试验,研究了连退工艺中均热温度和均热时间对其组织性能的影响。结果表明,当均热温度由780℃提高到820℃时,钢中生成的奥氏体含量增加,连退板马氏体体积分数、晶粒尺寸、屈服强度、抗拉强度、伸长率等均有增加。当均热温度为820℃,均热时间由86.4 s延长到129.6 s时,马氏体体积分数、晶粒尺寸略有增加,而较长的保温时间也促进了小角度晶界的回复,使得位错密度降低,从而导致退火板屈服强度降低,伸长率增加。

In order to formulate a reasonable production process of DP780 high strength automobile steel,the continuous annealing test was carried out,and the effects of soaking temperature and soaking time on its microstructure and properties were studied.The results show that when the soaking temperature increases from 780℃to 820℃,the austenite content in the steel increases,and the martensite volume fraction,grain size,yield strength,tensile strength and elongation rate of the continuous annealing sheet increase too.When the soaking temperature is 820℃and the soaking time is extended from 86.4 s to 129.6 s,the volume fraction of martensite and grain size increase slightly,and the longer soaking time also promotes the recovery of small angle grain boundary,which result in the decrease of dislocation density,and leads to the decrease of yield strength and increase of elongation rate.