不同焊接速度下ZK60镁合金自持式搅拌摩擦焊接头的显微组织
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摘要
在不同焊接速度(100～400mm·min~(-1))下对3mm厚ZK60镁合金进行自持式搅拌摩擦焊接,研究了接头的显微组织。结果表明:接头焊核区截面呈哑铃形,在1/4轴肩半径处的后退侧焊核区上表面存在流动图案,在前进侧热机影响区存在向焊核区生长的带状组织;在不同焊接速度下,前进侧热机影响区与焊核区之间存在明显的界面,热机影响区材料发生塑性变形,并发生部分动态再结晶;在不同焊接速度下,前进侧焊核区均发生了动态再结晶,当焊接速度为300,400mm·min~(-1)时,此焊核区由细小的等轴状再结晶晶粒组成,其定向流动形貌消失。
Self-reacting friction stir welding was conducted on 3 mm thick ZK60 magnesium alloy at different welding speeds(100-400 mm·min~(-1)),and then the microstructure of the joint was studied.The results show that the weld nugget zone of the joint had a dumbbell-shaped cross section.Flow patterns were observed near upper surface of the weld nugget zone on retreating side at the 1/4 radius of the shoulder.The advancing-side thermal mechanical affected zone was comprised of a banded structure stretching to the weld nugget zone.At different welding speeds,the interface between the advancing-side thermal mechanical affected zone and the weld nugget zone was obvious.The materials in the advancing-side thermal mechanical affected zone were deformed plastically,and the dynamic recrystallization occurred partially.The advancing-side weld nugget zone had a dynamic recrystallization at different welding speeds,and consisted of fine equiaxed dynamic recrystallization grains at 300 mm·min~(-1) and 400 mm·min~(-1);the flow pattern in one direction disappeared.
Self-reacting friction stir welding was conducted on 3 mm thick ZK60 magnesium alloy at different welding speeds(100-400 mm·min~(-1)),and then the microstructure of the joint was studied.The results show that the weld nugget zone of the joint had a dumbbell-shaped cross section.Flow patterns were observed near upper surface of the weld nugget zone on retreating side at the 1/4 radius of the shoulder.The advancing-side thermal mechanical affected zone was comprised of a banded structure stretching to the weld nugget zone.At different welding speeds,the interface between the advancing-side thermal mechanical affected zone and the weld nugget zone was obvious.The materials in the advancing-side thermal mechanical affected zone were deformed plastically,and the dynamic recrystallization occurred partially.The advancing-side weld nugget zone had a dynamic recrystallization at different welding speeds,and consisted of fine equiaxed dynamic recrystallization grains at 300 mm·min~(-1) and 400 mm·min~(-1);the flow pattern in one direction disappeared.
引文
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[17]MARIE F,GUERIN F,DELOISON D,et al.Investigation on bobbin tool friction stir welding of 2000series aluminum thin sheets[C]//Proceedings of 7th International Symposium on Friction Stir Welding.Awaji Island,Japan:TWI Ltd.,2008:1-19.
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[2]侯军才,张秋美,房中学.锻造ZK60镁合金的搅拌摩擦焊工艺[J].机械工程材料,2009,33(8):36-39.
[3]TAMADON A,PONS D J,SUED K,et al.Formation mechanisms for entry and exit defects in bobbin friction stir welding[J].Metals,2018,8(1):33.
[4]WANG F F,LI W Y,SHEN J,et al.Effect of tool rotational speed on the microstructure and mechanical properties of bobbin tool friction stir welding of Al-Li alloy[J].Materials&Design,2015,86:933-940.
[5]DONG J,GAO C,LU Y,et al.Microstructural characteristics and mechanical properties of bobbin-tool friction stir welded 2024-T3aluminum alloy[J].International Journal of Minerals,Metallurgy,and Materials,2017,24(2):171-178.
[6]XU W F,LUO Y X,FU M W.Microstructure evolution in the conventional single side and bobbin tool friction stir welding of thick rolled 7085-T7452 aluminum alloy[J].Materials Characterization,2018,138:48-55.
[7]THREADGILL P L,AHMED M M Z,MARTIN J P,et al.The use of bobbin tools for friction stir welding of aluminium alloys[J].Materials Science Forum,2010,638/639/640/641/642:1179-1184.
[8]SHEN J,WANG F,SUHUDDIN U F H,et al.Crystallographic texture in bobbin tool friction-stir-welded aluminum[J].Metallurgical and Materials Transactions A,2015,46(7):2809-2813.
[9]LI W Y,FU T,HTSCH L,et al.Effects of tool rotational and welding speed on microstructure and mechanical properties of bobbin-tool friction-stir welded Mg AZ31[J].Materials&Design,2014,64:714-720.
[10]HORTON K R.Micro-hardness,strength and strain field characterization of self-reacting friction stir and plug welds of dissimilar aluminum alloys[D].Tuscaloosa:University of Alabama,2011.
[11]SUED M K,PONS D,LAVROFF J.Design features for bobbin friction stir welding tools:Development of a conceptual model linking the underlying physics to the process[J].Materials&Design,2014,54(2):632-643.
[12]CHEN S J,LI H,LU S,et al.Temperature measurement and control of bobbin tool friction stir welding[J].The International Journal of Advanced Manufacturing Technology,2016,86(1/2/3/4):337-346.
[13]冯秀丽.高强铝合金搅拌焊接微观组织演变与力学性能预测[D].哈尔滨:哈尔滨工业大学,2012:33-43.
[14]ZHANG H J,WANG M,ZHANG X,et al.Microstructural characteristics and mechanical properties of bobbin tool friction stir welded 2A14-T6aluminum alloy[J].Material&Design,2015,65:559-566.
[15]HOU J C,LIU H J,ZHAO Y Q.Influence of rotation speed on microstructures and mechanical properties of 6061-T6aluminum alloy joints fabricated by self-reacting friction stir welding tool[J].The Internaitonal Journal of Advanced Manufacturing Technology,2014,73(5/6/7/8):1073-1079.
[16]LIU H J,HOU J C,GUO H.Effect of welding speed on microstructure and mechanical properties of self-reacting friction stir welded 6061-T6aluminum alloy[J].Material&Design,2013,50(7):872-878.
[17]MARIE F,GUERIN F,DELOISON D,et al.Investigation on bobbin tool friction stir welding of 2000series aluminum thin sheets[C]//Proceedings of 7th International Symposium on Friction Stir Welding.Awaji Island,Japan:TWI Ltd.,2008:1-19.
[18]SCHNEIDER J,NUNES A,BRENDEL M.The influence of friction stir weld tool form and welding parameters on weld structure and properties:Nugget bulge in self-reacting friction stir welds[C]//Proceedings of 8th International Symposium on Friction Stir Welding.Timmendorfer Strand,Germany:TWI Ltd.,2010:18-120.