双相区形变对含Cu低碳钢Cu配分行为及组织性能影响

Effect of intercritical region deformation on Cu partitioning,microstructure and mechanical properties of a Cu bearing low carbon steel

采用双相区形变+I&Q&P及I&Q&P(双相区等温-奥氏体化-淬火-碳配分)热处理工艺,研究了双相区形变对一种含Cu低碳钢Cu配分行为及其组织性能的影响。采用电子探针(EPMA)、扫描电镜(SEM)及透射电镜(TEM)等手段对元素配分行为及组织演变进行了表征。结果表明:实验钢经2种工艺处理后均出现Cu元素向逆转奥氏体的配分行为,采用双相区形变+IQ(双相区保温淬火)处理的组织中富Cu最高的区域面积为12.9%,比IQ工艺下富Cu区域提高108%;双相区形变+I&Q&P工艺处理后实验钢的晶粒明显细化,且组织中块状残余奥氏体较多;与单一I&Q&P工艺相比,双相区形变+I&Q&P工艺处理的实验钢抗拉强度由1 253MPa提高到1 293MPa,伸长率由16.9%提高到18.3%,残余奥氏体体积分数由11.6%提高到13.8%,表明双相区30%的形变处理实现了促进Cu配分行为诱导残余奥氏体含量增加和细晶强化的双重效果。

In order to study the effect of hot deformation on Cu partitioning, microstructure and mechanical properties, a combined process of intercritical region deformation plus intercritical heating austenitizing quenching and partitioning （I＆Q＆P） treatment was applied to a Cu bearing low carbon steel. The Cu partitioning behaviors and microstructures of the steel were characterized by means of EPMA, SEM and TEM. The results show that the Cu partitioning behavior into reversed austenite is found in both of test steels treated by different process, the highest Cu rich area of the test steel treated by intercritical region deformation plus intercritical heating quenching（IQ） process is 12.9%, increased by 108% than that treated by IQ process. After adding the hot deformation process, the grains of the test steel are obviously refined, and the blocky retained austenite in the microstructure is increased. Compared with the single I＆Q＆P process, the test steel treated by intercritical region deformation plus I＆Q＆P process has a better mechanical properties, the tensile strength increases from 1253MPa to 1293MPa, the elongation increases from 16.9% to 18.3%, and the retained austenite content increases from 11.6% to 13.8%, respectively. The results show that the 30% deformation in intercritical region can significantly promote the Cu partitioning on increasing the content of retained austenite and the effect of fine grain strengthening.