Residual Stresses Measurement in Hollow Samples Using Contour Method

Residual stresses are created usually undesirably during manufacturing processes, including casting, welding, metal forming, etc. Residual stresses alone or in combination with other factors can cause the destruction and fracture of components or significant decline in their service life. Therefore, it is crucial to measure the residual stresses. Contour method is a destructive testing method capable of measuring residual stresses of the cut surface along with being simple and low-cost. This method is able to create a two-dimensional map of residual stresses perpendicular to the sectioned surface. Measuring hollow samples is still a dilemma when using the contour method. In this study, hollow cylindrical samples with inner diameters of 20 and 40 mm were quenched at temperatures of 300ºC, 400ºC, and 850ºC. Both numerical analyses and experimental measurements were performed for the samples. The contour method was practiced for both hollow and filled samples. Overall review of the results was promising. However, the results obtained in the vicinity of the edges illustrated large deviations. Steel shafts were inserted to cylindrical holes to rectify the lack of constraint near the edges. The measurements on the filled samples were greatly improved.