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随焊余高碾压7075-T6铝合金接头组织和性能

Microstructure and mechanical properties of 7075-T6 aluminum alloy joint by welding with reinforcement rolling

  • 摘要: 为了改善7075-T6铝合金熔化焊接头的力学性能,提出了随焊余高碾压(welding with reinforcement rolling,WR)方法. 采用自行设计的随焊碾压装置在焊接过程中对焊缝余高同步进行碾压,利用万能试验机和维氏硬度计对不同工艺参数下的不同接头进行力学性能测试,并通过配置EDS和EBSD探头的扫描电镜对电弧焊接试样和随焊碾压试样的焊缝区和热影响区分别进行组织观察. 结果表明,随焊余高碾压工艺成功通过一次成形获得7075-T6铝合金高强度焊接接头,接头强度系数达到81.4%,相对电弧焊接头提升24%.焊缝强度的提高主要由于位错密度的增大和小角度晶界的增加,而晶粒尺寸及第二相分布对接头力学性能的影响比较小.

     

    Abstract: To improve the mechanical properties of 7075-T6 aluminum alloy fusion welded joints, the welding with reinforcement rolling process was proposed. In-situ rolling of the weld reinforcement was performed during the welding process using a self-designed welding with rolling device. Vickers hardness tester and universal testing machine were used to show the hardness distribution and tensile strength of the joint at different rolling temperatures. The microstructure of the fusion zone (FZ) and heat-affected zone (HAZ) were observed by scanning electron microscope configured with EDS and EBSD. The finite element simulation model of the 7075-T6 aluminum alloy welding with reinforcement rolling was established. The results show that the hardness of the FZ and the solid solution region in HAZ of the joints can be significantly improved by the WR process, and the strength coefficient of the joints reaches about 81.4%, which is 24% higher than that of the conventional arc welded joints. Mechanical properties are significantly improved due to the increase in low angle grain boundaries and dislocation density, with less correlation to grain size and second phase distribution.

     

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