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<p>This study investigates the fatigue performance of Q690D high-strength steel, including both the base metal and its welded joints, through experiments involving electron backscatter diffraction (EBSD) and high-cycle fatigue testing. The research assessed how factors such as average dislocation density, grain size, recrystallization degree, and texture influence the fatigue failure of the base metal and welded joints. Findings reveal that the base metal possesses a smaller average grain size and lower dislocation density, exhibiting an ultimate fatigue strength of 600&#xa0;MPa, which indicates favorable mechanical and fatigue characteristics. Conversely, the welded joints are prone to fatigue failure in the heat-affected zone (HAZ), attributed to a higher dislocation density and larger average grain size, resulting in an ultimate fatigue strength of 220&#xa0;MPa.</p>

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Comparison in Microstructure, Mechanical Properties, and Fatigue Behavior of Q690D High-Strength Steel and its Welded Joint

  • 期刊论文

  • 发表日期：

    2025年10月1日

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  • Chenglong Liu,
  • Youping Sun,
  • Junming Li,
  • Rong Ma,
  • Wangzhen Li,
  • Jiangmei He,
  • Xinyu Liu

摘要

This study investigates the fatigue performance of Q690D high-strength steel, including both the base metal and its welded joints, through experiments involving electron backscatter diffraction (EBSD) and high-cycle fatigue testing. The research assessed how factors such as average dislocation density, grain size, recrystallization degree, and texture influence the fatigue failure of the base metal and welded joints. Findings reveal that the base metal possesses a smaller average grain size and lower dislocation density, exhibiting an ultimate fatigue strength of 600 MPa, which indicates favorable mechanical and fatigue characteristics. Conversely, the welded joints are prone to fatigue failure in the heat-affected zone (HAZ), attributed to a higher dislocation density and larger average grain size, resulting in an ultimate fatigue strength of 220 MPa.