高功率激光焊接汽车用高强钢B450LAD组织与性能

采用15 kW CO3激光器对1.8 mm厚的热镀锌薄板B450LAD进行了高功率激光焊接.对工艺优化后所得到的4组焊接工艺规范参数的焊接接头进行宏观与微观组织分析、显微硬度试验以及拉伸力学性能试验.结果表明,在激光功率5.8～12.9 kW以及焊接速度3～7 m/min参数下,1.8 mm厚13450LAD镀锌钢板均可获得成形良好、无缺陷的焊缝;焊缝截面呈上宽下窄的倒梯形,热影响区(HAZ)相当窄;焊缝熔化区组织均为马氏体、细晶区组织为少量马氏体和铁素体;其焊缝中心显微硬度约为母材(BM)的2倍;焊接接头具有良好的拉伸力学性能,且4种拉伸试样均断于母材处.实验的4组工艺参数可作为此钢材不同应用场合下高功率激光焊接的工艺参考.

Structure and Properties of High Power Laser Welding of High Strength Steel B450LAD for Vehicles

Experiments of high power laser welding of 1.8 mm thick galvanized steel B450LAD are performed by using a 15 kW CO2 laser. Four sets of welding process parameters are acquired through process optimization. The macrostructure and microstructure analysis, microhardness measurements and tensile tests have been done on these four welded joints. It is shown that sound welds can be achieved on 1.8 mm thick B450LAD steel at a laser power of 5.8～12.9 kW and a welding speed of 3～7 m/min. The weld section looks like an inverted trapezia and the heat affect zone (HAZ) is very narrow. Martensite structure is found in weld center and little martensite with more ferrite structure is observed in fine grained region . The hardness in weld center is 2 times as high as the base material. The welded joints show good tensile properties, and all tensile specimens are broken in the base material (BM). So these four groups of welding parameters can be used for guiding the actual high power laser welding of B450LAD at different applications.