LNG船用薄板Invar36激光搭接焊工艺参量优化

为了解决殷瓦合金焊接中易出现的焊接缺陷问题，研究了液化天然气(LNG)船用薄板殷瓦合金搭接焊(上下板厚度均为1.5mm)工艺参量。通过设计制造气体保护盒，采用数值仿真分析和正交试验的方法，进行了理论分析和实验验证，取得了殷瓦合金搭接焊最优工艺参量。结果表明，气孔缺陷在完全保护气下得到有效抑制，殷瓦合金搭接焊的最优工艺参量为激光功率3.4kW、焊接速率1.3m/min、离焦量+20mm、激光入射角5°、激光光斑能量分布2∶1;在此最优工艺参量下，焊缝表面呈银白色，无气孔等缺陷，焊缝处硬度小于母材但大于热影响区，拉伸强度为417.16MPa，达到母材的94.8%，且仿真结果与试验结果误差较小，证明了本文中所建立的仿真模型的可靠性。这一结果对殷瓦合金激光搭接焊工艺参量数据库搭建是有帮助的。

Process parameters optimization of laser lap welding of thin plate Invar36 for LNG ships

In order to solve the problem of welding defects in Invar alloy welding,the technological parameters of Invar alloy lap welding(the thickness of the upper and lower plates with 1.5mm)for liquefied natural gas(LNG)ship sheet were studied.Though designing and manufacturing a gas protection box,by means of numerical simulation analysis and orthogonal experiment,the optimal process parameters of Invar alloy lap welding were obtained.The experimental results show that the porosity defects are effectively suppressed under complete shielding gas,and the optimal technological parameters for the lap welding of Invar alloy are obtained as:Laser power is 3.4kW,welding speed is 1.3m/min,defocus is+20mm,laser incident angle is 5°,and laser spot energy distribution is 2∶1,respectively.Under the optimal process parameters,the weld surface is silvery white,and there is no defect such as air holes.The hardness of the weld is smaller than that of the base metal but larger than that of the heat affected zone.The tensile strength is 417.16MPa,which is 94.8%of that of the base metal.The error between the simulation results and the test results is small,which proves the reliability of the simulation model established in this paper.This result is helpful for the construction of the later process parameter database of Invar laser lap welding.