304不锈钢激光拼焊及其焊缝组织研究

Laser Tailor-Welding of 304 Austenitic Stainless Steel And Microstructure Characteristics of Welds

采用连续光纤激光器进行了0.5 mm和1 mm厚304不锈钢薄板的对接拼焊。研究了焊接速度、离焦量、保护气类型对焊缝成形及性能的影响,通过对焊缝熔透性、焊缝形貌的分析,得到了优化的焊接工艺参数。实验结果表明,在氩气保护条件下,激光输出功率为200 W,焊接速度为120 mm/min,离焦量为0时,焊缝质量良好,焊缝组织呈明显的柱状晶组织特征,由奥氏体和残余δ铁素体组成。随着焊接速度的提高,焊缝的拉伸强度逐渐减小。当焊接速度为120 mm/min时,焊缝的拉伸强度最高达562 MPa,接近母材强度。

The butt joining of 0.5/1.0 mm thickness 304 austenitic stainless steel plates was carried out using continuous wave fiber laser. And the influence of welding speed, defocusing amount and shielding gas on weld forming and performance was studied by analysis of the weld penetration and morphology to optimize the welding parameters. The results showed that good welding quality can be achieved in such welding parameters （i.e. shielding by argon, laser power of 200 W, welding speed of 120 mm/min, and defocusing amount of zero. And the microstructure of weld, which was made up of austenitic and residual ferrite, showed clearly columnar grains oriented from interfaces to weld centre. Tensile test on the specimen mechanical property with different welding speed showed that the highest tensile strength is 562 MPa with welding speed of 120 mm/min, approximating to the mother material, and then decreasing gradually with the increase of welding speed.