压铸镁合金激光堆焊层的组织与力学性能  

Microstructure and Mechanical Properties of Laser Repair Welded Layer for Die Cast Magnesium Alloy

作　　者：倪加明[1] 杨学勤[1] 罗志强[1] 李宝辉[1] 黄坚[2] 

机构地区：[1]上海航天精密机械研究所,上海201600 [2]上海交通大学上海市激光制造与材料改性重点实验室,上海200240

出　　处：《热加工工艺》2015年第15期42-44,48,共4页Hot Working Technology

摘　　要：采用光纤激光填丝焊接技术进行压铸镁合金薄壁构件的缺陷补焊,利用扫描电镜和拉伸试验机进行分析与测定,着重研究了激光功率对补焊层组织及力学行为的影响规律。结果表明,通过方案和工艺参数优化,获得了成形良好的多层多道焊缝,未发现裂纹和夹杂缺陷。激光填丝补焊层以α-Mg树枝晶为基体,其上分布粒状、棒状的β-Mg17Al12强化相颗粒。由于晶粒细小,激光补焊层焊缝组织拥有良好的强韧性。激光功率=2.4 k W时,拉伸断裂强度高达250 MPa,伸长率为8.6%,优于母材铸造组织。然而,激光功率≥2.6 k W时,母材熔化过多,将导致焊缝性能恶化。The defect repair of die cast magnesium alloy was conducted by novel fiber laser welding technology with filler wire. The microstructure of laser repair welded layer was analyzed by SEM and XRD. The mechanical behavior was measured by tensile machine. Furthermore, the effect of laser power was discussed. The results show that multi-layer and multi-pass repaired layer without crack can be obtained after technique optimization. The microstructure of repair welded layer consists of α-Mg dendrite and dispersive granular precipitation of β-Mg17Al12. Because of the fine grain size, the repair welded layer h takes high strength and toughness. The ultra tensile strength and the ductility of repair welding layer at 2.4 k W laser power is 250 MPa and 8.6%, respectively. They are higher than those of die cast magnesium. Under the condition of laser power ≥2.6k W, because of the more melting of the matrix, the mechanical property of the repair layer deteriorates.

关 键 词：激光填丝焊接 压铸镁合金 缺陷修补 多层多道 

分 类 号：TG456.7[金属学及工艺—焊接]