High-speed butt welding of magnesium alloy using pulsed laser-arc hybrid heat source

Laser-arc hybrid welding at a speed of 6 000 mm/min is carried out on 2 mm thick magnesium alloy AZ61 plateand completely-penetrated butt joints are obtained, lnvestigations of the influence of parameters on weld formation show that Ihe addition of pulsed laser can effctively enhance tlle heat penetrability attd directivity nf the hybrid heat source. Measurements on microstructures and mechanical properties the joint indicate that grain in the.fhsion zone is refined and the grain size is sensitive to the arc current ; the fitsioa zone exhibits the highest hardaess; the tensile strength of the joint reaches 93% of base metal; there is the brittle fracture along the grain bozmdaries in the fusion zone. High-speed camera images exhibit that although the two adjacent laser pulses can not overlap, the recorery relaxation of the concentrated electric arc after laser intlse action can still maintain the continuous welding process.

压水堆驱动机构钩爪激光与GTAW钴基合金堆焊层组织分析及性能表征

控制棒驱动机构( Control rod drive mechanism,CRDM)是压水堆反应堆本体中唯一的能动设备,是集结构力学、电磁学、流体力学、传热学、自动控制等于一体的设备。钩爪部件形状复杂、结构精密,是压水堆( PWR)一回路的运动执行部件,其销轴孔与齿部钴基合金堆焊层组织与性能要求极高。本工作通过氩弧焊( GTAW)、激光焊( LBW)两种工艺试验,获得了满足设计要求的工艺参数。对两种工艺获得的钴基合金堆焊熔敷层进行了组织表征与分析,比较了两种工艺熔敷层的宏观与微观形貌差异,对熔敷层显微硬度进行了测试与对比分析,对熔敷层界面处的Co、Cr、Fe 等元素进行了线扫描,通过Fe 元素的分布分析了两种不同熔敷层稀释率与硬度差异的关系。两种堆焊层均未观察到微裂纹、夹杂、气孔、未熔合等缺陷,激光熔敷钴基堆焊层晶粒最细,因细晶强化作用,其显微硬度也最高。