Residual stress evaluation in API 5L X65 girth welded pipes joined by friction welding and gas tungsten arc welding

The present study compared the residual stress states in friction welded pipes of API 5L X65 to those achieved by gas tungsten arc welding (GTAW). X-ray diffraction (XRD) was used to assess residual stresses. In addition, microstructural and microhardness were analyzed for both welding processes. As expected, results showed that each welding method led to different residual stress states. The friction technology led to coarser microstructure, increased microhardness and lower residual stress states at the weld centreline. On the other hand, fusion welding was responsible for higher heterogeneity microhardness at the weld centerline, greater residual stress distributions and porosity formation in the joint cross section.