核级316LN不锈钢激光填丝堆焊技术研究

Research on the laser cladding of nuclear grade 316LN stainless steel

采用高功率光纤激光对核级316LN不锈钢板材进行填丝堆焊,焊材选用308L不锈钢焊丝,研究了激光功率、堆焊速度、送丝速度等工艺参数对焊道成形、显微组织及力学性能的影响。结果表明:工艺参数的组合必须保证焊接以熔池过渡形式进行,才能获得良好的成形效果,其中试验所得的最优工艺参数组合为:激光功率3 k W,堆焊速度4 mm/s,送丝速度40 mm/s。在最佳工艺参数条件下,可以制备出表面波纹均匀、平整度高的堆焊层,且显微硬度分布比较均匀,搭接界面无明显硬化,抗拉强度与伸长率高达705MPa和48%,分别为母材的115%和88%。堆焊层的显微组织为外延生长的柱状树枝晶,且晶粒细小、均匀。

The nuclear grade 316 LN stainless steel plates were claded by 308 L filler wire using a higher power fiber laser and the effects of welding parameters including laser power,travel speed and wire feed rate on the weld appearances,microstructures and mechanical properties were investigated.The results showed that the high-quality weld bead could be obtained by using optimal parameters where in the filler wire tip was immersed in the molten pool and was melted by heat of molten metal with high temperature.Using the optimal parameters of lase power 3 kW,travel speed 4 mm/s and wire feed rate 40 mm/s,the microstructures of the weld bead were characteristic of fine and even epitaxial columnar grains.The microhardness of the bead was uniform without obvious hardened zone near the fusion boundary and the ultimate tensile strength and elongation rate of the weld metal were 705 MPa and 48%,which were up to 115%and 88%of the base metal.