脉冲电流对超窄间隙中绝缘固壁约束片状钨极电弧加热特性的影响  

Influence of Pulsed Current for Heating Characteristic of Groove in Ultra-narrow Gap Welding with Sheet Tungsten Electrode Arc Constricted by Insulating Solid Wall

作　　者：李渊博 郑文星 叶韬 麻帅川 赵锡龙 LI Yuanbo;ZHENG Wenxing;YE Tao;MA Shuaichuan;ZHAO Xilong(School of Materials Science and Engineering,Lanzhou Jiaotong University,Lanzhou 730070)

机构地区：[1]兰州交通大学材料科学与工程学院,兰州730070

出　　处：《机械工程学报》2023年第22期302-311,共10页Journal of Mechanical Engineering

摘　　要：针对SUS304奥氏体不锈钢,采用脉冲电流和绝缘固壁联合调控的方式,改善片状钨极电弧对超窄间隙坡口加热特性,能够在降低热输入前提下保证坡口底部、坡口侧壁和坡口底角熔合良好。同时,结合不同脉冲电流频率、占空比和平均电流等脉冲电流参数下超窄间隙焊缝截面形貌和几何特征参数的对比分析,以及焊接热循环曲线、约束脉冲电弧压力峰值及电弧形态变化规律,明确脉冲电流和绝缘固壁耦合作用下片状钨极电弧对超窄间隙坡口加热特性的调控机理。结果表明,脉冲电流频率、占空比、平均电流和绝缘固壁约束作用对片状钨极电弧的协同影响是调控电弧加热特性的主要因素;脉冲电流频率的增加会增强脉冲电弧尖峰作用和电弧自磁压缩效应,最终导致坡口底部加热效果加强而坡口侧壁加热效果减弱;改变占空比会引起脉冲电弧热作用和脉冲电弧尖峰作用产生此消彼长的变化趋势;当占空比增加时,强化的脉冲电弧热作用首先占据主导并增强其对超窄间隙坡口的加热效果;此后,一旦弱化的脉冲电弧尖峰作用使电弧压力显著降低时,片状钨极电弧对超窄间隙坡口的加热效果将随之减弱;平均电流和绝缘固壁的耦合影响不仅会大幅提升片状钨极电弧对坡口底部的热力作用,还会限制坡口侧壁加热效果的强化。The new method for welding of SUS304 austenitic stainless-steel is proposed to improve the heating characteristics of pulsed current sheet tungsten electrode arc constricted by insulating solid wall on groove in ultra-narrow gap.The bottom,side and corner in ultra-narrow gap groove could obtain good fusion in lower heat input by this method.Meanwhile the heating mechanisms of pulsed current sheet tungsten electrode arc constricted by insulating solid wall on ultra-narrow gap groove would be understood by comparative analysis of transverse weld morphology,geometric parameters with variation of pulse current frequency,duty cycle and average welding current,thermal cycle curve,peak pressure of pulsed arc and arc shape.The results show the synergistic effects of pulse current frequency,duty cycle,average welding current and constriction by insulating solid wall on sheet tungsten electrode arc would determinate the heating characteristics on groove in ultra-narrow gap;the raise of pulse current frequency would intensify the pulsed arc peak effect and self-induced magnetic compression,by which the heating effects on bottom in groove would be strengthened and on side in groove would be weakened;the variation of duty cycle would cause opposite tendency for thermal effect of pulsed arc and pulsed arc peak effect;when the duty cycle increased,the strengthened thermal effect of pulsed arc would enhance heating effect on groove,once the weakened pulsed arc peak effect could dominate,the heating effect on groove would be decimated;the couple effect of average welding current and constriction by insulating solid wall on sheet tungsten electrode arc could not only reinforce the heating effect on bottom in groove but also restrict the intensification of heating effect on side in groove.

关 键 词：脉冲电流 超窄间隙焊接 加热特性 

分 类 号：TG444[金属学及工艺—焊接]