Residual Stress Measurement in Socket Welded Joints by Neutron Diffraction

Neutron diffraction measurements of lattice spacings provide the spatial map of residual stress near welds in ferritic steel socket joints. The high tensile stress greater than 200MPa was found in the fusion and heat-affected zones in the hoop direction. However, the highest tensile stress in the axial direction at the weld root was about 110MPa relatively lower than the expected value from the fatigue test results. The balancing compressive stress was found near the surface of the socket weld fusion zone. Heat treatment at 625°C for 2 hours was sufficient for the relief of residual stress in socket welds.