SUS304不锈钢超薄片脉冲激光焊接工艺及接头的显微组织和力学性能

在不同激光功率(140～420 W)和焊接速度(10～30 mm·s^-1)(即不同热输入)下对SUS304不锈钢超薄片(厚度0.2mm)进行脉冲激光搭接焊,研究了热输入对焊缝成形的影响,并分析了最优成形接头的显微组织和力学性能。结果表明:当热输入在9～20J·mm^-1时可获得成形良好的焊缝,其中在激光功率320 W、焊接速度20mm·s^-1(热输入16J·mm^-1)条件下的成形性能最优;最优成形接头焊缝中心为等轴晶组织,熔合线处为细小柱状晶组织,近熔合线的焊缝中形成了胞状树枝晶;最优成形接头熔合线处的硬度最高,其次为焊缝区;不同激光功率和焊接速度所得接头均在热影响区发生断裂,最优成形接头的抗拉强度最高,达到790.1MPa,接近于母材的,其拉伸断裂方式为韧性断裂。

Pulsed Laser Welding Process of SUS304 Stainless Steel Sheet and Microstructure and Mechanical Properties of Joint

Pulsed laser lap welding was conducted on SUS304 stainless steel sheets(0.2 mm thick),at different laser power(140-420 W)and welding velocities(10-30 mm·s^-1),namely different heat input.The influence of heat input on the weld formation was studied,and the microstructure and mechanical properties of the joint with optimal formability were analyzed.The results show that a well-formed weld can be obtained when the heat input was in the range of 9-20 J·mm^-1;the forming performance was the best at laser power of 320 Wand welding velocity of 20 mm·s^-1(heat input of 16 J·mm^-1).The microstructure in the weld center of the joint with optimal formability consisted of equiaxed grains,in the fusion line consisted of fine columnar grains,and in the weld near fusion line of cellular dendrites.The hardness at the fusion line of the welded joint with optirnal formability was the highest,followed by the weld zone.The joints obtained at different laser power and welding velocities all fractured in the heat-affected zone.The tensile strength of the joint with optinal formability was the highest of 790.1 MPa,which was close to that of the base metal,and the tesile fracture mode was ductile.