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采用YLS-10000光纤激光器和ERNiMo-8焊丝,对液化天然气船液罐用9Ni钢进行了超窄间隙激光焊接,研究了接头组织和性能。结果表明,优化焊接参数可以得到侧壁熔合良好的超窄间隙接头。焊缝组织主要为奥氏体,两侧结晶形态为柱状晶,中心为等轴晶。热影响区分为明显的粗晶区和细晶区,组织均为马氏体和少量残余奥氏体,硬度均值约为340HV,远高于母材均值(230HV)和焊缝均值(200HV)。拉伸试样均断于焊缝,接头抗拉强度略低于母材的。随着与焊缝中心距离的增大,接头的低温冲击功增大,且均值都在70J以上。断口形貌均为细小的韧窝,接头为韧性断裂。
The ultra-narrow gap laser welding of 9Ni steel for LNG tanker was carried out with YLS-10000 fiber laser and ERNiMo-8 wire. The joint organization and properties were studied. The results show that the optimization of the welding parameters can obtain a good fusion of the narrow sidewall gap joints. Austenitic weld microstructure mainly on both sides of the crystal form of columnar crystals, the center is equiaxed. The thermal effects are divided into obvious coarse and fine grain regions. The microstructure is martensite and a small amount of retained austenite. The average hardness is about 340 HV, much higher than the mean value of the base metal (230 HV) and the mean value of the weld (200 HV). Tensile specimens were broken in the weld joint tensile strength slightly lower than the base metal. As the distance from the weld center increases, the low temperature impact energy of the joint increases, and the average value is above 70J. Fracture morphology are small dimples, joint toughness fracture.