Abstract

Friction stir welding (FSW) and gas tungsten arc welding (GTAW) were employed to manufacture the spiral pipes by a double-sided synchronization approach. The fatigue crack growth properties for base metal (BM) and welded metal (WM) in FSW and GTAW were studied using standard compact tension specimens manufactured from the welded pipes of the AA 5754 aluminum alloys. The highest crack growth rate occurred in WM of GTAW specimen, while WM of FSW specimen showed the lowest crack growth rate. Moreover, the crack growth rate of BM specimen fell in between them. This was because of the combination of the coarse grains and a high residual stress in WM of GTAW in comparison with WM of FSW and BM. The increase in fatigue crack rate matched well with the variation in the plastic region at the crack tip.

中文翻译：

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AA 5754铝合金钨极氩弧焊与搅拌摩擦焊接头的疲劳裂纹扩展特性

摘要

采用摩擦搅拌焊（FSW）和气体钨极电弧焊（GTAW）通过双面同步方法制造螺旋管。使用由AA 5754铝合金焊接管制成的标准紧凑型拉伸试样，研究了FSW和GTAW中贱金属（BM）和焊接金属（WM）的疲劳裂纹扩展性能。GTAW试样的WM出现最高的裂纹扩展速率，而FSW试样的WM则显示最低的裂纹扩展速率。而且，BM试样的裂纹扩展率在它们之间。这是因为与FSW和BM的WM相比，GTAW的WM中存在粗大晶粒和较高的残余应力。疲劳裂纹率的增加与裂纹尖端塑性区域的变化非常吻合。