冷却工艺对DP700热轧双相钢组织及性能的影响

Effect of cooling process on microstructure and mechanical properties of DP700 hot-rolled dual-phase steel

采用实验室热轧实验研究了二段冷却(空冷+水冷)工艺和三段冷却(水冷+空冷+水冷)工艺对DP700热轧双相钢组织及性能的影响。结果表明,二段冷却时,随着中间温度的降低,铁素体含量增加,屈服强度和抗拉强度都逐渐降低。增大第二阶段冷却速度有利于抗拉强度的提升。当卷取温度为545℃时,实验钢的组织为F+B,拉伸曲线中出现屈服平台,当卷取温度低于410℃时,实验钢的组织为F+M。与二段冷却相比,三段冷却获得的铁素体含量更多且晶粒更细小,马氏体分布更加均匀,屈强比有较为显著的降低。

The effects of two-stage cooling(air-cooled + water-cooled) process and three-stage cooling(water-cooled + air-cooled + water-cooled) process on the microstructures and mechanical properties of DP700 hot-rolled dual-phase steel have been investigated by hot rolling experiment at laboratory. The results show that, in the two-stage cooling, with the decrease of intermediate temperature, the ferrite volume fraction increases and both yield strength and tensile strength gradually decrease. Increasing the second stage cooling rate is beneficial to the increase of tensile strength. When the coiling temperature is 545 ℃, the microstructure of experimental steel is F+B, and the yield plateau appears in the tensile curve, and when the coiling temperature is lower than 410 ℃, the microstructure of experimental steel is F+M. Compared with the two-stage cooling, the ferrite volume fraction of the three-stage cooling is more and finer, the martensite distribution is more uniform, and the yield ratio is more significantly reduced.