Plasma-MIG Hybrid Welding Hot Cracking Susceptibility of 7075 Aluminum Alloy Based on Optimum of Weld Penetration

被引:9
作者
Shao Yingkai [1 ]
Wang Yuxi [1 ]
Yang Zhibin [1 ]
Shi Chunyuan [1 ]
机构
[1] Dalian Jiaotong Univ, Sch Mat Sci & Engn, Dalian 116028, Peoples R China
关键词
7075 aluminum alloy; plasma-MIG hybrid welding; weld penetration; welding hot cracking susceptibility; MECHANICAL-PROPERTIES; AL; MICROSTRUCTURE;
D O I
10.11900/0412.1961.2017.00357
中图分类号
TF [冶金工业];
学科分类号
0806 ;
摘要
The 7075 aluminum alloys have major applications in commercial, transportation industry and military air carriers, owing to their associated light weight, high strength, good machinability, high fracture toughness and low fatigue crack growth. Several welding techniques, such as metal inert gas (MIG) welding, tungsten inert gas (TIG) welding, laser welding and friction stir welding (FSW), have been applied to weld the 7075 aluminum alloys. However, their applications are limited because of the lower weld strength, slower welding speed and other significant limitations of them. Among the different welding techniques, plasma-MIG hybrid welding is a new fabrication technique with many advantages such as stable welding process, no weld spatter, the decreased pores, small grain size and high joint quality. Up to now, the study mainly focuses on coaxial plasma-MIG hybrid welding, and it is rare in dealing with the hot cracking susceptibility of 7000 senes aluminum alloys welded by paraxial plasma-MIG hybrid welding. In this work, the paraxial plasma-MIG hybrid welding system was used to weld 7075-T6 aluminum alloy plates. The quantitative relationship between plasma-MIG hybrid welding parameters of 7075 aluminum alloy and weld penetration was established by linear regression orthogonal test. Hot ductility tests were studied by using the thermal simulated test to determine the brittleness temperature range of the alloy. Welding hot cracking susceptibility tests were conducted by using the fish bone method, and the type and cause of the hot cracking were analyzed by SEM, EDS and OM. The results indicated that the brittleness temperature range of 7075 aluminum alloy was 470 similar to 620 degrees C. When the heat inputs of plasma-MIG hybrid welding were 2.52, 2.95 and 3.42 kJ/cm respectively, the welding hot cracking susceptibility decreased and then increased with the heat input increasing. The type of cracking in partially melted zone of base metal was liquation cracking, and that of weld zone was solidification cracking. When the heat input was 2.95 kJ/cm, the welding hot cracking sensitivity was the least, and the welding cracking was solidification cracking. Compared to MIG weld-ng joints, the hot cracking susceptibility of plasma-MIG hybrid welding joints decreased by 47% under the same conditions.
引用
收藏
页码:547 / 556
页数:10
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