The effects of Cr contents (0.3 and 1.0 wt.%) and isothermal holding temperatures (400, 440, and 480 °C) on the microstructure evolution and properties of complex phase steel with high formability (CH steel) were investigated using dilatometry, scanning electron microscopy, transmission electron microscopy (TEM), and X-ray diffraction. The results show that the microstructures of CH steel with 0.3 wt.% Cr are ferrite, granular bainite, martensite, and retained austenite, while no ferrite is observed in the microstructure of CH steel with 1.0 wt.% Cr in the same process. Cr promotes the precipitation of (Nb, Ti)C in the high-temperature austenite region through theoretical calculations and TEM observations. Cr retards the bainite transformation and refines the grain size of CH steel. Furthermore, as isothermal holding temperature increases from 400 to 480 °C, the bainite and retained austenite fractions of two CH steels decrease, while the martensite fraction increases in the steels after final quenching. Consequently, the strength has an increasing tendency and the total elongation has a decreasing tendency with increasing isothermal temperature.

采用膨胀法、扫描法研究了 Cr 含量（0.3 和 1.0 wt.%）和等温保温温度（400、440 和 480 °C）对高成型复合相钢（CH 钢）组织演变和性能的影响。电子显微镜、透射电子显微镜 (TEM) 和 X 射线衍射。结果表明，添加0.3 wt.% Cr的CH钢的显微组织为铁素体、粒状贝氏体、马氏体和残余奥氏体，而添加1.0 wt.% Cr的CH钢在同一工艺中的显微组织中没有观察到铁素体。Cr通过理论计算和TEM观察促进了(Nb, Ti)C在高温奥氏体区的析出。Cr 延缓了贝氏体相变，细化了 CH 钢的晶粒尺寸。此外，随着等温保持温度从 400 ℃增加到 480 ℃，两种 CH 钢的贝氏体和残余奥氏体分数减少，而最终淬火后钢中的马氏体分数增加。因此，随着等温温度的升高，强度有增加的趋势，总伸长率有降低的趋势。