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<p>This study investigates the macroscopic formation, microstructure, and mechanical properties of welded joints based on the seven-wire rotating arc (SRA) electrogas welding (EGW) method, adjusting the shielding gas atmosphere with the same welding conditions. The results indicate that as the CO₂ content in the shielding gas increases, both the average welding speed and wire melting rate exhibit a corresponding upward trend. Specifically, the maximum welding speed and wire melting rate reached 6.97 cm/min and 147.54 g/min, respectively. With the increase in oxygen potential of the shielding gas, the microstructure of the weld seam tends to coarsen. Concurrently, the content of proeutectoid ferrite (PF) shows an increasing trend, while the acicular ferrite (AF) content undergoes a gradual decrease. The hardness distribution of welded joints obtained under different shielding gas conditions follows a general pattern of weld zone (WZ) &gt; heat-affected zone (HAZ) &gt; base metal (BM). When an appropriate amount of O₂ is added to the shielding gas, oxide particles are prone to form in the weld seam. These formed oxide particles act as heterogeneous nucleation sites, which not only refine the grain size and improve the uniformity of the microstructure but also further enhance the toughness of the weld seam. Notably, the weld seam achieves the optimal toughness when the shielding gas composition is 80% Ar + 16% CO₂ + 4% O₂. Under this condition, the transverse tensile strength and longitudinal tensile strength reach 565 MPa and 600 MPa, respectively, and the Charpy impact energy reaches 90 J at − 20℃.</p>

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Influence of Different Shielded Gases on Welding Performance in SRA EGW

  • 期刊论文

  • 发表日期：

    2026年2月24日

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  • Yong Chen,
  • Xianrui Zhao,
  • Tao Zhang,
  • Wangwang Yu,
  • Yefang Wang,
  • Yulang Xu,
  • Chenfu Fang

摘要

This study investigates the macroscopic formation, microstructure, and mechanical properties of welded joints based on the seven-wire rotating arc (SRA) electrogas welding (EGW) method, adjusting the shielding gas atmosphere with the same welding conditions. The results indicate that as the CO₂ content in the shielding gas increases, both the average welding speed and wire melting rate exhibit a corresponding upward trend. Specifically, the maximum welding speed and wire melting rate reached 6.97 cm/min and 147.54 g/min, respectively. With the increase in oxygen potential of the shielding gas, the microstructure of the weld seam tends to coarsen. Concurrently, the content of proeutectoid ferrite (PF) shows an increasing trend, while the acicular ferrite (AF) content undergoes a gradual decrease. The hardness distribution of welded joints obtained under different shielding gas conditions follows a general pattern of weld zone (WZ) > heat-affected zone (HAZ) > base metal (BM). When an appropriate amount of O₂ is added to the shielding gas, oxide particles are prone to form in the weld seam. These formed oxide particles act as heterogeneous nucleation sites, which not only refine the grain size and improve the uniformity of the microstructure but also further enhance the toughness of the weld seam. Notably, the weld seam achieves the optimal toughness when the shielding gas composition is 80% Ar + 16% CO₂ + 4% O₂. Under this condition, the transverse tensile strength and longitudinal tensile strength reach 565 MPa and 600 MPa, respectively, and the Charpy impact energy reaches 90 J at − 20℃.