核级316LN不锈钢焊接接头的组织结构变化

Microstructure of nuclear grade 316LN stainless steel welded joint

通过光学显微镜、扫描电镜、透射电镜、电子背散射衍射、X射线衍射仪和硬度测量仪等方法对核级316LN焊接接头不同区域的组织结构进行了系统研究,结果表明,焊缝区冷却凝固模式以铁素体-奥氏体(F-A)为主,残留的铁素体以蠕虫状或板条状形式存在奥氏体基体上,含量约为13.66%.熔合区宽度不统一,凝固模式以奥氏体-铁素体(A-F)为主,并且具有明显的外延生长趋势;热影响区发生不同程度的再结晶、晶粒长大和变形行为,Σ3晶界比例降低,而硬度和残余应力增大.

Optical microscope,scanning electron microscope,transmission electron microscope,electron back scattering diffraction,X-ray diffraction and hardness measurement were used to investigate the microstructure of the different zones in nuclear grade 316LN welded joints.The results show that,the solidfication type of weld zone was dominated by ferrite-austenite(F-A)mode,and the content of vermicular-or lath-like residual ferrite existed in the austenite matrix was 13.66%.The fusion zone solidficated in the form of austenite-ferrite(A-F)mode,and the width of which was not uniform.Moreover,the fusion zone exhibited the epitaxial growth tendency.Recrystallization,grain growth and deformation behavior with different degrees occurred in the heat-affected zone.Meanwhile,lessΣ3 grain boundary,high hardness and residual stress were found in the heat-affected zone.