工艺参数对激光扫描焊接接头形貌及性能的影响

Influence of welding parameters on morphology and mechanical properties of laser scanner welded joints

为获得高质量镀锌板焊接接头,采用激光扫描焊接方法对1.5 mm厚DP 780镀锌板进行搭接焊,研究激光功率、焊接速度对焊接接头的焊缝成形、显微组织及力学性能的影响。结果表明,激光功率和焊接速度分别在2.5~3.0 kW,25~55 mm/s区间内可获得全熔透焊缝;增大焊接功率,有利于消除焊缝表面咬边,但造成焊缝表面内凹现象严重;全熔透焊接时,增大焊接速度可减少焊缝内凹程度。焊缝中心主要由粗大的板条状马氏体组成,热影响区主要由马氏体和铁素体组成,降低焊接功率或增大焊接速度均可使马氏体组织含量减少及尺寸减小、铁素体含量增加。显微硬度试验表明焊接接头出现软化区,解释了接头拉伸性能在焊接速度55~75 mm/s范围内出现增大现象。焊接功率3.0 kW,焊接速度45 mm/s工艺参数组合最合适。

In order to obtain high quality welded joints of galvanized sheets,laser scanner welding method was used for lap welding of 1.5 mm thick DP 780 galvanized sheets,and effects of laser power and welding speed on weld formation,microstructure and mechanical properties of welded joints were studied.The results showed that full penetration welds were obtained when laser power and welding speed were in the range of 2.5~3.0 kW and 25~55 mm/s,respectively.Increasing welding power was beneficial to eliminate the undercut on the weld surface,while it caused serious recession on the back of the weld.In full penetration welding,increasing the welding speed reduced the degree of weld recession.The center of the weld was mainly composed of coarse lath martensite and the heat-affected zone was mainly made up of martensite and ferrite.Reducing welding power or increasing welding speed reduced the martensite content and size,and made ferrite content increased.The microhardness test showed that welded joints appeared a softened zone,it was explained that the tensile properties of joints increased in the range of 55-75 mm/s welding speed.The combination of welding parameters,3 kW welding power and 35 mm/s welding speed,was the most suitable.