316L不锈钢金属间相固溶过程中的微结构表征

利用扫描电镜、X射线衍射仪和电子背散射衍射仪等设备研究了热轧态316L不锈钢金属间相(σ相和χ相)在固溶过程中的微结构演变规律,同时,利用高温激光共聚焦显微镜对金属间相回溶的全过程进行了原位在线观察,确定了最佳固溶温度。结果表明,固溶过程中发生了γ+σ+χ→γ+σ+χ+α/FeCr→γ+α/FeCr的相变过程。金属间相的回溶从1033.1℃开始到1149.5℃结束,回溶时间为21s,消除金属间相的最佳固溶温度约为1150℃。固溶处理前,基体中分布的带状组织形态不规则,χ相和σ相的面积比分别为0.46%和0.94%;固溶处理后,带状组织形态一致,主要分布铁素体和FeCr相,而χ相和σ相不可见。

Microstructure characterization of intermetallic phases in 316L stainless steel during solution process

The microstructure evolution of intermetallic phases (σ phase and χ phase) in hot rolled 316L stainless steel during solution process was studied by means of scanning electron microscope (SEM), X-ray diffractometer (XRD) and electron backscatter diffractometer (EBSD). Meanwhile,the high temperature laser confocal microscope was used to observe the whole in-situ re-dissolution of intermetallic phases. The optimal solution temperature was determined. The results indicated that the phase transition process of γ+σ+χ→γ+σ+χ+α/FeCr→γ+α/FeCr occurred during solution process. The re-dissolution of intermetallic phases started at 1033.1℃ and ended at 1149.5℃. The re-dissolution time lasted for 21 seconds, and the optimum solution temperature for eliminating intermetallic phases was about 1150℃. Before the solution treatment, the morphology of banded structure distributed in the matrix was irregular, and the area percentages of χ phase and σ phase was 0.46% and 0.94%, respectively. After the solution treatment, the morphology of banded structure was uniform and mainly distributed in the form of ferrite and FeCr phase, while χ phase and σ phase were not observed.