焊后热处理对核聚变用316LN焊接接头的影响

Influence of post-weld heat treatment on the 316LN welded joints for nuclear fusion

采用了TIG对核聚变用316LN奥氏体不锈钢进行焊接,并对焊接接头进行了焊后热处理,利用光学显微镜、扫描电镜分析手段研究了焊后热处理对焊接接头微观组织和力学性能的变化。试验结果表明,焊缝中为奥氏体组织,并未发现第二相析出物存在。焊后热处理对接头的拉伸性能影响不大,均断裂在母材位置,但显著提高了接头的延伸率。接头低温冲击试验也展现了良好的抗低温冲击性能。断口分析发现,接头呈韧性断裂。

In order to study the post weld heat treatment （PWHT） of the austenitic stainless steel 316LN, the effects on the microstructure and mechanical properties in TIG welded joints of 316LN austenitic stainless steel for nuclear fusion with the PWHT were investigated. The observation on the microstructure and mechanical properties change in weld were carried out by employing optical microscopy and scanning electron microscopy. The results show that the microstructure of the weld was fully austenite structure, and no precipitated phases were observed. The PWHT has a little effects on the tensile properties of the welded joint, the fracture of the tensile sample were all located at the base metal, while the elongation was enhanced notably after the PWHT. In the low temperature impact tests of the welded joints, the good resistance to this impact emerged, and the impact fracture mode of all samples were presenting ductile fracture according to the fracture analysis.