Measurement of residual stresses in weld repairs in steels

Abstract Welding residual stresses have important consequences on the performance of engineering components. Residual stresses are more likely to be significant in repair welds since they are small, more highly constrained and faster cooling than large construction welds. In repair welds the loss of integrity due to residual stress can be even more important that in welds in general since the area being repaired has already failed probably due to high loadings. In the research presented in this chapter the neutron diffraction technique was used to investigate the residual stress distributions in carbon steel components with weld repairs. Two full penetration weld repairs were made using (a) the stringer bead and (b) the temper bead weld techniques in 25 mm thick plate. The welds were not post-weld heat treated. The focus of the measurements is on the values of the sub-surface and through-thickness strain/stress variations near the middle and the toe of the weld. The measurements were compared with current fitness-for-purpose approaches, such as BS7910 and R6, showing that these approaches underestimated and overestimated the stresses in various regions. The experimental results showed that both processes had high residual stresses particularly through the thickness. From the point of view of residual stress the temper bead weld appears no better than the stringer bead weld.

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