The distribution of residual stresses (RS) in repairs generated by Friction Hydro-Pillar Processing (FHPP) in AISI H13 was investigated. Three axial force levels, with consequent different deposition rates, were applied to replicate possible repaired conditions. The contour (CM) and X-ray diffraction (XRD) methods were employed for RS analysis in samples that were also evaluated through metallography, microhardness analysis, micro-tensile and Charpy testing. CM produced 2D maps of the RS in the joints, showing symmetrical distributions around the welded rod for all welded conditions. Other common features for all conditions were the maximum level of compressive RS, which was found in the TMAZ of the rod, and the maximum tensile residual stress, which was found near the HAZ of the base block. There was good agreement between the RS measurement techniques. Mechanical tests show similar tensile resistance for all conditions and an apparent increase in toughness at higher force levels.
Residual stresses (RS) in pipes welded by a fully automated friction welding process, called FRIEX, are investigated using the contour method (CM) and the X-ray diffraction method (XRD). Samples were produced using a self-developed equipment, which is based on the interaction between a consumable intermediate rotary ring and two stationary pipe sections, by varying the loading rate applied during the welding of API 5L B pipes with an API X65 ring. Mechanical and metallurgical properties were locally analyzed through metallography and microflat tensile tests. RS measured by XRD and CM showed comparable values; tensile zones were found in the pipe HAZ and compressive stresses were found in its adjacent areas. Tensile RS of approximately half the local yield strength of the components were also found, mostly on the internal surface, and their values decrease with increasing welding loads. Microflat tensile tests showed an increase in yield strength of pipe TMAZ and HAZ, with a clear influence of loading rates.
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