Tensile Residual Stress Fields Produced In Austenitic Alloy Weldments

Residual stresses developed by prior machining and
welding may either accelerate or retard stress corrosion
cracking (SCC), in austenitic alloys, depending upon
their magnitude and sign. A combined x-ray diffraction
(XRD) and mechanical technique was used to
determine the axial and hoop residual stress and yield
strength distributions into the inside diameter surface of
a simulated Alloy 600 penetration J-welded into a
reactor pressure vessel. The degree of cold working
and the resulting yield strength increase caused by prior
machining and weld shrinkage were calculated from the
line broadening distributions. Tension as high as +700
MPa was observed in both the axial and hoop
directions at the inside diameter adjacent to the weld
heat affected zone (HAZ). Stresses exceeding the bulk
yield strength develop due to the combined effects of
cold working of the surface layers during initial
machining, and subsequent weld shrinkage. Cold
working produced by prior machining was found to
influence the final residual stress state developed by
welding.