I&Q&P下双相区配分温度对含铜低碳钢组织与性能的影响

Effect of dual-phase region partitioning temperature on microstructure and properties of low carbon steel containing copper by I&Q&P process

采用场发扫描电镜、X射线衍射仪和电子探针研究了双相区合金元素不同配分温度对0.12C-1.33Mn-0.55Cu钢的组织性能和残留奥氏体含量的影响。结果表明:试验钢在双相区配分后,C、Cu和Mn元素均出现明显的配分效果,且Cu、Mn元素配分作用有利于盐浴分级淬火C配分进行,保留更多残留奥氏体提高塑性;I&Q&P工艺处理得到马氏体和残留奥氏体组织,随着双相区配分温度提高原奥氏体晶粒尺寸变大,马氏体板条变粗,位向增多;随着配分温度的提高,试验钢的抗拉强度提高,伸长率逐渐下降,残留奥氏体含量的变化趋势与伸长率基本一致,在780℃时强塑积最大为26 GPa·%,此时残留奥氏体体积分数为14.7%,伸长率为24.4%,综合力学性能最佳。

Effect of alloying elements in dual phase region with different partitioning temperature on microstructure, properties and retained austenite content of 0.12C-1.33Mn-0.55Cu steel was studied by means of scanning electron microscopy （SEM）, tensile tests, electron microprobe analysis （EPMA） arid X-ray diffraction （XRD）. The results show that C, Cu and Mn elements of the tested steel in the dual- phase region partition appear apparent partition effect. The partitioning of Cu and Mn may promote the C partitioning during salt bath marquenching to retain more retained austenite and increase plasticity. The microstructure after I＆Q＆P process is martensite and retained austenite. With the increase of partitioning temperature, original austenite grain size of the steel in the I＆Q＆P process become larger, and martensite lath gets coarse, and the orientation increases. The tensile strength of the tested steel increases and the elongation gradually decreases with the increase of partitioning temperature. Simultaneously, the volume fraction of retained austenite and elongation show basically the same trend. When the partitioning temperature is 780℃, the product of strength and elongation reaches maximum on 26 GPa · %, the volume fraction of retained austenite is 14.7% and elongation rate is 24.4%. The comprehensive mechanical properties is the best.