Hastelloy C-276/316L脉冲激光异质焊接微观组织研究

Study on Microstructure of Pulse Laser Welding on Dissimilar Materials Hastelloy C-276 and 316L

为评价激光焊接AP1000部件工艺的可靠性,探究Hastelloy C-276与316L异质焊接焊缝的元素偏析及组织结构,利用Nd:YAG脉冲激光进行焊接,借助光学显微镜和电子探针X射线微区分析仪等分析测试仪器,对焊缝显微组织、元素成分及金相形貌进行分析。结果表明:焊缝组织晶粒细化,焊缝中部以细小等轴晶为主、边缘以柱状晶为主,且焊接接头两侧热影响区极窄;依据元素宏观分布,焊缝可分为3个区域,焊缝两侧元素成分急剧变化,中部均匀;元素存在微观偏析,晶界处Mo元素富集。焊缝组织以γ奥氏体为主,并未发现明显δ铁素体生成。

To estimate the reliability of laser welding components of AP1000 and study the distribution of elements and microstructure of dissimilar weld of Hastelloy C-276 and 316L welded by Nd. YAG pulse laser, the microstructure, element distribution and phase of the weld were systematically analyzed by optical microscope, electron probe X- ray mieroanalyser and other analysis, measuring and test instruments. The results show that the gain of microstructure of weld is refined, and tiny equiaxed grains are in the center and columnar grains are near the weld edge. Heat-affected zones are very narrow on two sides of the weld joint. According to macro distribution of elements, there are three zones in the weld. Element compositions vary drastically on two sides of the weld and become uniform in the center. Micro-segregation of elements exists and Mo enrichedat the grain boundary of the weld is observed. Austenite is the main microstructure of the weld and little delta ferrite is found.