高压干法GMAW熔滴排斥过渡形成机理

采用红外激光作为背光源，应用高速摄像系统对高压干法GMAW熔滴过渡进行了研究.以三种不同送丝速度，分别进行了0.1～2 MPa的氩气环境GMAW试验.结果表明，随着环境压力的增加，熔滴过渡形式均转变为排斥过渡.在排斥过渡熔滴长大过程中，始终伴随着电弧弧根沿一侧上爬至熔滴的近焊丝端现象，从而对熔滴产生了不对称的侧向力作用，加之高压环境中弧根面积减小导致熔滴所受的电磁力为熔滴过渡的阻力，两者共同作用最终形成了高压干法GMAW的排斥过渡.通过对比不同环境压力下的弧根位置照片发现，这种弧根上爬现象也同时存在于常压和环境压力较低时.并采用理论模型推导了电弧弧根上爬的条件及影响因素.

Generating mechanism of repelled transfer mode in dry hyperbaric GMAW

The metal transfer of dry hyperbaric GMAW was investigated with high speed camera system and infrared laser backlight. The experiments were carried out with three different wire-feeding speeds at ambient pressure of 0.1 MPa~2 MPa. The results show that the transfer mode changed finally to repelled transfer with the increase of ambient pressure. During droplet formation, the arc root always rose along the droplet surface to the welding wire, which caused asymmetric side force on the droplet. In addition, the electromagnetic force was resistance force due to contraction of arc root area in hyperbaric environment. Comparing the photos of arc root location at different ambient pressures, the arc root rising phenomenon also appeared at normal and low pressures. The generating condition and influential factors were derived by theoretical model.