不同焊接工艺下304不锈钢薄壁管件纵缝微观组织及力学性能研究

Microstructure and Mechanical Properties of 304 Stainless Steel Thin Wall Pipe Longitudinal Seam under Different Welding Processes

分别采用钨极氩弧焊(TIG)和激光焊对304不锈钢薄壁管件实施纵缝焊接。通过光学显微镜、电子扫描显微镜、显微硬度计对两种焊接接头的组织性能进行观察测试及对比分析。结果表明:TIG焊缝中心组织由奥氏体等轴晶和蠕虫状铁素体组成,激光焊接头焊缝中心组织由垂直于熔合线外延方向生长的柱状晶组成。TIG焊接头各部位晶粒尺寸明显大于激光焊接头的,且热影响区明显宽于激光焊接接头的,激光焊接头的热影响区宽度仅约为20μm。TIG焊接与激光焊接的焊缝显微硬度值分别约为150、190 HV,两种焊接接头的显微硬度分布规律均是热影响区>母材>焊缝。

The longitudinal seam welding of 304 stainless steel thin wall pipe was carried out by using tungsten argon arc welding(TIG) and laser beam welding(LBW), respectively. The microstructure and mechanical properties of the welded joints were observed and tested by optical microscope, scanning electron microscope and microhardness tester. The results show that the microstructure of the TIG weld center is austenite equiaxed crystal and worm ferrite, and the microstructure of the laser weld center is composed of columnar crystals growing perpendicular to the fusion line. The grain size of the TIG welded joint is obviously larger than that of laser welded joint, and the heat affected zone is obviously wider than that of laser welded joint, the width of heat affected zone of the laser welded joint is only about 20μm. The average microhardness values of weld zone of the TIG and laser welded joints are about 150 HV and 190 HV,respectively. The microhardness distribution law of the two welded joints is heat affected zone > base metal > weld zone.