Investigating the effectiveness of the Incremental Deep-Hole Drilling residual stress measurement technique within a cracked, MSIP pipe.

Residual stress measurements and modelling are crucial for understanding the structural integrity and performance of materials. This study investigated the application of the Incremental Deep-Hole Drilling (iDHD) technique to measure the residual stresses within a stainless steel, girth-weld pipe containing a machined, partial-arc, inner surface crack. After welding and following the subsequent creation of the crack, the pipe was subjected to the Mechanical Stress Improvement Process (MSIP) before iDHD measurements were carried out. The locations of the iDHD measurements were such that the iDHD core (i.e. gauge volume) included the crack, and so measuring the remnant welding residual stresses after cracking and MSIP. A zone of high magnitude residual stresses was measured in front of the crack tip which induced the plastic release of residual stresses during the measurement process. The accuracy of the iDHD measurements were then investigated using finite element (FE) analysis considering the presence of the crack within the iDHD core. Nominal girth weld with MSIP residual stress profiles were mapped into an FE model of the pipe and the iDHD process was simulated. The results showed the effectiveness of the iDHD technique even with the crack present and the effect of the plastic release of the residual stresses in front of the crack tip on the standard Deep-Hole Drilling (DHD) results.