MEASUREMENT OF RESIDUAL-STRESS IN THE WELD OVERLAY PIPING COMPONENTS

In general industry, especially in the nuclear industry, welding overl ay repair is an important repair method mainly used to rebuild piping systems suffering from intergranular stress-corrosion cracking (IGSCC) . The pipe surface is mechanically ground to obtain a smooth surface a fter the welding overlay repair. A better understanding of the effect of repair and grinding processes on the residual stresses at the surfa ce of weld overlay is required. To obtain this understanding, it is ne cessary to measure directly the distribution of residual stresses on t he specimen. It is expected that compressive residual stress should be induced at the inner wall surface of the pipe for prevention of IGSCC . The performance evaluation of welding overlay repair relies on wheth er or not the level and characteristic of the residual stress can be m easured accurately. In this study, the hole-drilling strain-gage metho d, using the incremental drilling technique, was adopted to estimate t he residual stresses on the inner and outer walls of the weld overlay pipe. The experimental results indicate that the residual stress at th e pipe inner surface is compressive while that of the outer surface is tensile. Also, it is found that the depth affected by grinding is abo ut 1.016 mm.