环境压力对高压干法GMAW熔滴过渡影响分析

Effect of ambient pressure on droplet transfer in hyperbaric GMAW

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.通过0.4 MPa以内氩气环境的试验发现,环境压力超过临界压力后熔滴过渡形式会发生转变.随着环境压力的增加,在小电流情况下,过渡形式先由大滴过渡转变为短路过渡,进而转变为排斥过渡;在焊接电流较大情况下,熔滴依次呈现射流过渡、短路与射流混合过渡、排斥过渡.并从熔滴受力的角度分析了压力环境熔滴过渡形式转变机理.指出产生排斥过渡的原因是在环境压力的作用下电弧与弧根收缩,改变了熔滴的受力状态而产生的.

The droplet transfer of hyperbaric GMAW was investigated with high speed camera system and infrared laser backlight. Based onthe experiments within 0. 4MPa argon environment,it was found that thedroplet transfer mode would be changed if ambient pressure exceeding critical pressure. In the case of low current,as the ambient pressure increases,droplet transfer mode changes to globular transfer,short-circuiting transfer,and repelled transfer. In the case of high current,droplet transfer mode changes to streaming transfer,short-circuiting and streaming mixed transfer,and repelled transfer with increasing ambient pressure. The transition mechanism of metal transfer mode was explained by the droplet force analysis. The arc and its root are contracted at elevated ambient pressure,which results in the force condition changes and the droplet repelled transfer formation.