Study on strength properties of material repaired by atmospheric plasma spraying under tensile load

Abstract

In this study, capability and reliability of advanced repairing technology based upon thermal spraying technique are examined. In order to achieve this purpose, the damage evolution progressed in the repaired part is clarified through continuous observation under tensile loading, and residual stress and the critical strain up to the delamination of the repaired part were identified. As the results, the continuous observation revealed that crack was initiated and propagated along the interface in the repaired part during a tensile loading, which brought about a dog-legged shape deformation in the whole specimen. It was recognized that the repaired part was peeled off as the repairing length (L) became long. From relationship between the repairing length normalized by the depth (L/h) and residual stress and the critical strain on double plot style, it was found that residual stress increases to compressive side with the normalized repaired length, but the amount of residual stress (order in 50MPa) was very low in comparison with one (order in 500MPa) known in a welding technique. The critical strain also increased with the length, which means that it is desirable to remove a large region from the damage part in the structure. It can be claimed that APS repairing technique has great capability in place of a traditional welding approach.