The specimens were machined such that plug weld was centered on the width of the specimen . 对试件进行了机加工以使塞焊焊缝位于试件宽度中间。
2.
No spalled paint exists at the plug weld and for a short distance each side of the plug welds . 在塞焊焊缝处及塞焊周围距离内无细漆碎屑存在。
3.
Close examination of the plug welds showed the existence of herringbone patterns near the slag and voids in welds . 对塞焊焊缝的详细检查表明在焊渣及气孔附近，焊缝中存在着人字型裂纹。
4.
Thus the fracture likely initiated from fatigue sharpened cracks originating from slag and void in the plug welds . 因此，断裂可能是由于从塞焊焊缝内的焊渣和气孔外形成的尖锐的疲劳裂纹而产生的。
5.
Development and key problem of friction plug welding 摩擦塞焊研发与关键问题
