304不锈钢薄板列置双TIG高速焊缝组织与性能

相比常规速度不锈钢焊接，高速焊接过程中焊缝金属的凝固过程及组织形态将会发生变化，从而影响焊缝组织和性能. 对1.2 mm厚304不锈钢薄板对接，采用列置双TIG焊在焊接速度为3.0 m/min时获得了良好焊缝成形，并与常规速度单TIG焊接工艺相比，采用非标准拉伸试样测试了焊缝性能，并分析了其组织. 结果表明，高速双TIG焊接焊缝中心生成等轴晶，两侧树枝晶未形成对向生长的定向晶粒，焊缝抗拉强度及断后伸长率略低于母材；相比常规单TIG焊接工艺，高速双TIG焊接热影响区晶粒平均直径降低了10.3%，但焊缝中心晶粒平均直径增大了12.9%；焊缝抗拉强度和断后伸长率分别提高了4.3%和23.2%，焊缝中心硬度值略高于母材.

Microstructure and properties of weld by high-speed tandem TIG welding of thin 304 stainless steel plate

Compared with the welding of stainless steel at the conventional welding speed, the microstructures and properties of joint can be affected by the solidification process, which would be changed in high-speed welding. The butt welds with good weld appearance were obtained by tandem tungsten inert gas (tandem TIG) welding 304 stainless steel plate of 1.2 mm thickness at the welding speed of 3.0 m/min. And compared with the conventional single TIG welded joint, the properties of welds by tandem TIG welding were studied by nonstandard tensile specimens, and the microstructures were analyzed. The experimental results showed that the equiaxed grains formed in the weld center, the directions of dendrite grains on both side of weld center were not the opposite in tandem TIG weld, and the tensile strength and elongation of tandem TIG weld were slightly lower than that of base metal. Compared with the conventional single TIG welding, the average diameter of the grain in heat affected zone of tandem TIG joint decreased by 10.3 %, but the average diameter of the grain in weld center increased by 12.9 %, the tensile strength and elongation of tandem TIG weld increased by 4.3 % and 23.2 %, respectively. The micro-hardness in weld center of tandem TIG welded joint were slightly higher than that of base metal.