焊接过程中锆合金板材的温度在300 ℃以上时锆合金易吸收氢、氧、氮等气体杂质,这些气体杂质使得锆合金的力学性能急剧下降，加强焊缝及热影响区的隔离保护和合理制定焊接工艺参数是获得优良焊接质量的关键。以光纤激光器为热源，对厚度为0.7 mm 的Zr-Sn-Nb-Fe（锆锡铌铁）合金薄板进行激光对接焊试验，采用ANSYS有限元软件，建立激光对接焊非线性三维传导有限元模型，模拟计算Zr-Sn-Nb-Fe合金薄板的温度场分布。结果表明：模拟计算获得的熔池形状、尺寸与实际焊缝基本吻合，验证了采用高斯面热源模型来模拟Zr-Sn-Nb-Fe合金薄板激光对接焊温度场的合理性；温度场最终呈现流星状的稳定分布，焊缝附近等温线密集，焊缝熔宽窄，热影响区小，板材表面温度在300 ℃以上的区域的宽度随激光功率的增大而增大，随焊接速度的增加而减小；在激光功率为1300~1500 W，焊接速度为50~70 mm/s，离焦量为+1~+2 mm，氩气保护喷嘴直径为8~12 mm的条件下，Zr-Sn-Nb-Fe合金焊接试样的抗拉强度与母材基本相当，获得了良好的焊缝质量，焊缝无气孔、裂纹等缺陷，晶粒细小,主要元素含量相对母材无明显变化，焊接试样具备较高力学性能。

Hydrogen, oxygen, nitrogen and other gas impurities can be easily absorbed by zirconium alloys above 300 ℃ during the laser welding process, thus the mechanical property is drastically reduced. The key to ensuring the quality of zirconium alloy welding is to establish reasonable welding process parameters and strengthen the isolation protection for the welding seam and heat affected zone. Laser butt welding test on the 0.7 mm Zr-Sn-Nb-Fe alloy sheet with fiber laser as thermal source is carried out. Based on the ANSYS software, a nonlinear three dimensional (3D) transient heat conduction model is established by means of the finite element analysis. Simulation is done to get the temperature field distribution of the Zr-Sn-Nb-Fe alloy thin sheet. The results show that the weld profile and dimension obtained by simulations are basically consistent with those of the real welds, which verifies the rationality of adopting Gaussian heat source model to simulate the temperature field of Zr-Sn-Nb-Fe alloy thin sheet by laser butt welding. The temperature field presents a stable meteor-shaped distribution, the isotherms are dense near the weld, and the heat affected zone is narrow. The width of the area above 300 ℃ increases with the increment of laser power, but decreases with the increment of the welding speed. When the laser power is 1300~1500 W, the welding speed is 50~70 mm/s, the defocusing amount is +1~+2 mm, and the argon gas protection nozzle diameter is 8~12 mm, the tensile strength of Zr-Sn-Nb-Fe alloy welded specimens roughly equals to that of the base metal. The weld quality is good, air holes and cracks do not exist, the grain is small, and the contents of the main elements have no obvious changes if compared with that of parent metal. The welded specimens with a high mechanical property are obtained.