钨极惰性气体保护焊和金属惰性气体保护焊AA6082-T6管状接头显微组织与力学特性的对比研究（英文）
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摘要
采用钨极惰性气体保护焊和金属惰性气体保护焊两种工艺对T6态AA6082合金管进行焊接,比较所得焊接接头的显微组织特性和力学性能。利用光学显微镜,拉伸测试和显微硬度测试研究焊接工艺的影响。结果表明,由于形成了细小的等轴晶且枝晶间距较小,TIG焊接接头的拉伸强度比MIG焊接接头的拉伸强度高,强度可提高25%。在焊接效率方面,TIG焊接可得到更可靠的强度,与MIG焊接相比,其强度可提高25%。两种焊接工艺焊缝区的硬度都大幅度降低,这是由于高温时材料发生了相变。MIG焊接样品的硬度较低,为1.08GPa。MIG焊接接头的热影响区比TIG焊接接头的稍大,这是由于单位长度的热输出更大。
The present study is aimed to compare the microstructure characteristics and mechanical properties of AA6082 in T6 condition of tubular joints fabricated by tungsten inert gas welding(TIG) and metal inert gas welding(MIG) processes. The effect of welding processes was analysed based on optical microscopy image, tensile testing, and Vickers micro-hardness measurements. The results showed that the tensile strengths of the TIG-welded joints were better than those of the MIG-welded joints, due to the contribution of fine equiaxed grains formation with narrower spacing arms. In terms of joint efficiency, the TIG process produced more reliable strength, which was about 25% higher compared to the MIG-joint. A significant decay of hardness was recorded in the adjacent of the weld bead zone, shown in both joints, related to phase transformation, induced by high temperatures experienced by material. A very low hardness, which was about 1.08 GPa, was recorded in the MIG-welded specimens. The extent of the heat-affected-zone(HAZ) in the MIG-welded joints was slightly wider than those of the TIG-welded specimens, which corresponded with a higher heat input per unit length.
The present study is aimed to compare the microstructure characteristics and mechanical properties of AA6082 in T6 condition of tubular joints fabricated by tungsten inert gas welding(TIG) and metal inert gas welding(MIG) processes. The effect of welding processes was analysed based on optical microscopy image, tensile testing, and Vickers micro-hardness measurements. The results showed that the tensile strengths of the TIG-welded joints were better than those of the MIG-welded joints, due to the contribution of fine equiaxed grains formation with narrower spacing arms. In terms of joint efficiency, the TIG process produced more reliable strength, which was about 25% higher compared to the MIG-joint. A significant decay of hardness was recorded in the adjacent of the weld bead zone, shown in both joints, related to phase transformation, induced by high temperatures experienced by material. A very low hardness, which was about 1.08 GPa, was recorded in the MIG-welded specimens. The extent of the heat-affected-zone(HAZ) in the MIG-welded joints was slightly wider than those of the TIG-welded specimens, which corresponded with a higher heat input per unit length.
引文
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[2]KISSELL J,FERRY R.Aluminium structures—A guide to their specifications and design[M].2nd ed.New York:John Wiley&Sons,2002.
[3]MAZZOLANI F M.Aluminium alloy structures[M].2nd ed.London:Chapman&Hall,1995.
[4]EUROCODE 9.Design of aluminium structures.Part1-1:General structural rules.EN-1999-1-1[S].Brussels,2007.
[5]MADHUSUDHAN R G,GOKHALE A,PRASAD R K.Optimization of pulse frequency in pulsed current gas tungsten arc welding of aluminium-lithium[J].Journal of Materials Science&Technology,1998,14:61-66.
[6]MARKOVITS T,TAKACSA J,LOVAS A,BELT J.Laser brazing of aluminum[J].Journal of Materials Processing Technology,2003,143-144:651-655.
[7]COLLETTE M.The impact of fusion welds on the ultimate strength of aluminum structures[C]//Proceedings of 10th International Symposium on Pratical Pesign of Ships and Other Floating Structures.Houston,USA.2007.
[8]ERICSSON M,SANDSTR?M R.Influence of welding speed on the fatigue of friction stir welds,and comparison with MIG and TIG[J].International Journal of Fatigue,2003,25:1379-1387.
[9]MU?OZ A.C,RüCKERT G,HUNEAU B,SAUVAGE X,MARYA S.Comparison of TIG welded and friction stir welded Al-4.5Mg-0.26Sc alloy[J].Journal of Materials Processing Technology,2008,197:337-343.
[10]SQUILLACE A,de FENZO A,GIORLEO G,BELLUCCI F.A comparison between FSW and TIG welding techniques:Modifications of microstructure and pitting corrosion resistance in AA 2024-T3 butt joints[J].Journal of Materials Processing Technology,2004,152:97-105.
[11]ZHAO J,JIANG F,JIAN H,WEN K,JIANG L,CHEN X.Comparative investigation of tungsten inert gas and friction stir welding characteristics of Al-Mg-Sc alloy plates[J].Materials&Design,2010,31:306-311.
[12]BENOIT A,PAILLARD P,BAUDIN T,KLOSEK V,MOTTIN J B.Comparison of four arc welding processes used for aluminium alloy cladding[J].Science and Technology of Welding and Joining,2015,20:75-81.
[13]NORMAN A,DRAZHNER V,PRANGNELL P.Effect of welding parameters on the solidification microstructure of autogenous TIG welds in an Al-Cu-Mg-Mn alloy[J].Materials Science and Engineering A,1999,259:53-64.
[14]LAKSHMINARAYANAN A,BALASUBRAMANIAN V,ELANGOVAN K.Effect of welding processes on tensile properties of AA6061 aluminium alloy joints[J].International Journal of Advanced Manufacturing Technology,2009,40:286-296.
[15]BRITISH STANDARD BS 8118:Part 1:1991[S].London,1991.
[16]GEORGE F V V.ASM handbook on metallography and microstructures[M].Vol.9.Material Park,Ohio,USA:ASM International,2004.
[17]SAVAGE W F,ARONSON A H.Preferred orientation in the weld fusion zone[J].Welding Journal,1966,45:85-89.
[18]MONDOLFO L.Aluminium alloys-structure and properties[M].London:Butterworths,1997.
[19]MRóWKA-NOWOTNIK G.Influence of chemical composition variation and heat treatment on microstructure and mechanical properties of 6xxx alloys[J].Archives of Materials Science and Engineering,2010,46:6-13.
[20]MYHR OR,GRONG?.Process modelling applied to 6082-T6aluminium weldments—I.Reaction kinetics[J].Acta Metallurgica et Materialia,1991,39:2693-2702.
[21]MADHUSUDHAN R G,MOHANDAS T,CHANDRESHEKAR K.Observations on welding ofα2+O+βtitanium aluminide[J].Science and Technology of Welding and Joining,2001,6:300-304.
[22]POTLURI N,GHOSH P,GUPTA P,REDDY Y.Studies on weld metal characteristics and their influences on tensile and fatigue properties of pulsed current GMA welded Al-Zn-Mg alloy[J].Welding Journal,1996,75:62-70.