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王富义，等：多道焊接热循环对6082-T6铝合金接头热影响区显微组织及力学性能的影响

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Effect of Multiple Welding Thermal Cycling on Microstructure and Mechanical
Properties of Heat Affected Zone of 6082-T6 Aluminum Alloy Joint

WANG Fuyi , XIONG Hao , PENG Chao , YAN Dong , ZHAN Teng , XU Congchang , LI Luoxing 1,3
2
2
1
1
1
1
(1. College of Mechanical and Vehicle Engineering, Hunan University, Changsha 410082, China; 2. Hunan Lince Rolling
Stock Equipment Co., Ltd., Zhuzhou 412005, China; 3. Chongqing Research Institute of Hunan University,
Chongqing 401120, China)
Abstract: ER5087 aluminum alloy wires were cladded on a 6082-T6 aluminum alloy plate by double pulse melting
inert gas shielded welding for four passes, and specimens were taken at different positions in the welding heat affected
zone (HAZ) for microstructure observation and mechanical property tests. Combined with numerical simulation of
welding temperature field, the effect of multiple welding thermal cycling on the microstructure and mechanical properties
at different positions in the HAZ were studied. The results show that based on tested hardness variation and simulated
peak temperature variation of the cross section of the HAZ, combining with material heat treatment process, the HAZ of
6082-T6 aluminum alloy welded joint was divided into a over-aged zone (zone A), a severely over-aged zone (zone B),
and a solid solution zone (zone C) according to the distance ( from far to near) from fusion line. With the increase of
welding pass, the grain size of the HAZ became coarser; the precipitated phase in zone A changed from β″ phase+
β' phase→β' phase+U2 phase→β phase+β' phase+semi-dissolved phase→β' phase+semi-dissolved phase. After
different-pass welding, the precipitated phase in zone B was basically in semi-dissolved state, and the ordered precipitated
phase in zone C was completely dissolved and only a large amount of GP zones existed. With the increase of welding
pass, the precipitated phase in zone A and zone B of the HAZ was coarsened and dissolved gradually, and the number
of GP zones in zone C decreased. After four-pass welding, the overall mechanical properties of the HAZ decreased, and
the softening in zone B of the HAZ was the most serious. The main reason for softening of HAZ was the evolution of
precipitated phases rather than grain coarsening.
Key words: multiple welding thermal cycling; aluminum alloy joint; heat affected zone; mechanical property;
evolution of precipitated phase
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