镀锌板CMT焊焊缝气孔影响因素及产生机理
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摘要
镀锌板在车身材料中得到广泛应用,但其熔化极气体保护焊(GMAW, gas metal arc welding)存在气孔缺陷.从焊接电流模式、焊枪行进倾角、预留间隙、焊接保护气体成分和焊接电流焊接速度匹配等几个方面,研究其对镀锌板弧焊焊缝气孔影响规律及其气孔产生的机理,用X射线探伤对内部气孔进行观察统计.结果表明,冷金属过渡(CMT,cold metal transfer)焊由于其低热输入,内部气孔少,适合焊接镀锌板;焊枪行进倾角选用后倾焊(焊枪指向待焊区域)为佳;预留间隙可以显著抑制气孔产生;保护气体中加入适量CO_2可以减少气孔;焊接速度加快会减小气孔尺寸,但数量会有所增多.
Galvanized sheet has been widely used in automobile industry.However,there are many porosities in the welds of GMAW(gas metal arc welding).In this paper,the effects of welding process,torch moving angle,gap,shielding gas composition and welding speed on porosities were studied systematically.The internal porosities were observed and statistically analyzed by X-ray radiographic inspection.The results showed that CMT(cold metal transfer) welding was suitable for galvanized sheet and had less porosities because of its low heat input.It was better for porosities by using backward-welding(the welding torch points to the unwelded area),leaving the gap,and adding appropriate amount of CO_2 to the shielding gas.And higher welding speed produced more porosities with smaller size.
Galvanized sheet has been widely used in automobile industry.However,there are many porosities in the welds of GMAW(gas metal arc welding).In this paper,the effects of welding process,torch moving angle,gap,shielding gas composition and welding speed on porosities were studied systematically.The internal porosities were observed and statistically analyzed by X-ray radiographic inspection.The results showed that CMT(cold metal transfer) welding was suitable for galvanized sheet and had less porosities because of its low heat input.It was better for porosities by using backward-welding(the welding torch points to the unwelded area),leaving the gap,and adding appropriate amount of CO_2 to the shielding gas.And higher welding speed produced more porosities with smaller size.
引文
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[2]孔纲,卢锦堂,许乔瑜.热镀锌钢的研究进展[J].电镀与涂饰,2005,24(9):49-52.Kong Gang,Lu Jintang,Xu Qiaoyu.Research progress of hot dip galvanized steel[J].Electroplating&Finishing,2005,24(9):49-52.
[3]郭青华,陈静,李立军.汽车钣金件镀锌板应用研究[J].汽车工程师,2012(10):60-62.Guo Qinghua,Chen Jing,Li Lijun.Research on application of zinccoated steel panel in automotive sheet metal parts[J].Auto Engineer,2012(10):60-62.
[4]Lim Y M,Jang B S,Koh J H.The effect of shielding gas and arc voltage on the bead shape and pore generation of galvanized steel pipe welds with gas metal arc welding[J].Advanced Materials Research,2013,746:240-244.
[5]杨修荣.超薄板的CMT冷金属过渡技术[J].焊接,2005(12):52-54.Yang Xiurong.CMT technic of the ultrathin sheets[J].Welding&Joining,2005(12):52-54.
[6]上山智之.通过CBT方法开发低热输入低飞溅CO2/MAG交流焊接系统[J].电焊机,2009,39(9):10-13.Tomoyuki Ueyama.Development of low heat input and spatter reduction CO2/MAG alternating current welding system by controlled bridge transfer process[J].Electric Welding Machine,2009,39(9):10-13.
[7]张洪.EWM cold Arc“冷弧焊”--一种低能量的熔化极气体保护焊技术及其应用[J].焊接,2009(5):11-14.Zhang Hong.EWM cold arc welding:a gas metal arc welding technology with low energy and its application[J].Welding&Joining,2009(5):11-14.
[8]Izutani S,Yamazaki K,Suzuki R,et al.Blowhole generation phenomenon and quality improvement in GMAW of galvanized steel sheet[J].IJAT,2013,7(1):103-108.
[9]Cho S M,Kim K J,Lee B W.The waveform control and blowhole generation in the wave pulse MIG welding for galvanized steel sheets[J].Journal of Welding and Joining,2005,23(1):69-76.
[10]汪殿龙,张志洋,梁志敏.交流CMT动态电弧特征及熔滴过渡行为分析[J].焊接学报,2014,35(3):6-10.Wang Dianlong,Zhang Zhiyang,Liang Zhimin.Analysis of dynamic arc characteristics and droplet transfer behavior of AC-CMT[J].Transactions of the China Welding Institution,2014,35(3):6-10.
[11]杨新华.焊接方向与角度对焊缝成形的影响[J].现代焊接,2016(4):65-66.Yang Xinhua.Effect of welding direction and angle on weld shape[J].Modern Welding Technology,2016(4):65-66.