Residual stress analysis of friction stir welded AA6063 pipe butt joint by neutron diffraction technique of ENGIN-X

Abstract

Residual stress refers to stress that remains in a structure when all applied stresses have been removed. It is important because the combination with applied stress can cause failure at the level below at which the failure could occur. A study has been carried out using the non-destructive neutron diffraction (ND) technique of ENGIN-X to quantify the redistribution of residual stresses in a pipe. A three-dimensional residual stress-measurements test is fully performed on a 89 mm (3.5 in) diameter pipe in AA6063 grade aluminium (5 mm wall thickness) containing a girth friction stir weld. The results have shown an opposite residual stress effect due to tool rotational speed increment especially on the retreating side of the weld. This weld residual stress analysis is an important factor for Fitness-For-Purpose Assessments. This residual stress measurement data provides a basis for structural integrity assessment and inspection planning.