采用不同的工艺参数对6 mm厚超低碳440钢船体进行了搅拌摩擦点焊维修试验,并对接头的拉伸性能和冲击性能进行了测试与对比分析。结果表明,与维修前的超低碳440钢船体相比,采用搅拌摩擦点焊维修后的船体接头的室温抗拉强度增加了402 MPa,达到母材的98%;-40℃冲击吸收功增加140 J,达到母材的95%,实现了较高质量的船体维修;其优选的搅拌摩擦点焊工艺参数为:搅拌头旋转速度800 r/min、焊接速度250mm/min、轴肩下压量3.3 mm。 Friction stir spot welding repair test was carried out on 6 mm thick ultra-low carbon 440 hull with different process parameters. Tensile and impact properties of the joint were tested and compared. The results show that the tensile strength at room temperature of hull joints repaired by friction stir spot welding increases by 402 MPa to 98% of that of the parent material compared with the pre-service ultra-low carbon 440 hull. - The impact absorption energy at 40 ℃ increases 140 J, up to 95% of the base metal, to achieve a higher quality hull maintenance; the preferred friction stir spot welding process parameters: stirring head rotation speed 800 r / min, welding speed 250mm / min, shoulder under pressure 3.3 mm.