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<p>How to balance the strength and plasticity of metal materials has become a new challenge for industrial applications. Designing heterogeneous structures (HSs) on the surface of metallic materials has become a promising strategy for achieving strength–plasticity matching. In this study, by adjusting the parameters of ultrasonic impact treatment, bionic HS and gradient HS were constructed on the MIG joint surface of 6061-T6 aluminum alloy. The optimal conditions were identified as an impact current of 0.8&#xa0;A and an impact speed of 15&#xa0;mm/min, which yielded the lowest surface roughness and the minimized defects. Moreover, UIT remarkably refined the grain and precipitated phase size on the joint surface, inducing high-density dislocations and beneficial compressive residual stress. In addition, the tensile tests revealed that compared to as-welded sample, the gradient HS joint exhibited increases of 30&#xa0;pct in tensile strength and 45.6&#xa0;pct in yield strength, albeit with 36.3&#xa0;pct reduction in elongation, as a result of the large-area work-hardening effect. In contrast, the bionic HS joint achieved a more balanced combination of strength and plasticity due to the combined effect of various strengthening mechanisms. In comparison with as-welded sample, its tensile and yield strengths increased by 23.5 and 32.7&#xa0;pct, respectively, while elongation decreased by 22&#xa0;pct.</p>

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Effect of Heterostructure Constructed on Microstructure and Mechanical Properties of 6061-T6 Aluminum Alloy MIG Welded Joints via Ultrasonic Impact Treatment

  • 期刊论文

  • 发表日期：

    2026年4月21日

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  • Xiu Xin,
  • Shengguang Dai,
  • Yongheng Jiang,
  • Ziheng Song,
  • Ziyuan Chen,
  • Hang Chen,
  • Chao Meng

摘要

How to balance the strength and plasticity of metal materials has become a new challenge for industrial applications. Designing heterogeneous structures (HSs) on the surface of metallic materials has become a promising strategy for achieving strength–plasticity matching. In this study, by adjusting the parameters of ultrasonic impact treatment, bionic HS and gradient HS were constructed on the MIG joint surface of 6061-T6 aluminum alloy. The optimal conditions were identified as an impact current of 0.8 A and an impact speed of 15 mm/min, which yielded the lowest surface roughness and the minimized defects. Moreover, UIT remarkably refined the grain and precipitated phase size on the joint surface, inducing high-density dislocations and beneficial compressive residual stress. In addition, the tensile tests revealed that compared to as-welded sample, the gradient HS joint exhibited increases of 30 pct in tensile strength and 45.6 pct in yield strength, albeit with 36.3 pct reduction in elongation, as a result of the large-area work-hardening effect. In contrast, the bionic HS joint achieved a more balanced combination of strength and plasticity due to the combined effect of various strengthening mechanisms. In comparison with as-welded sample, its tensile and yield strengths increased by 23.5 and 32.7 pct, respectively, while elongation decreased by 22 pct.