Neutron diffraction measurements of residual strains in offshore welds

Residual stresses in an offshore weld may affect the fatigue life of the structure, and should hence be included in calculations of fatigue crack propagation and fatigue lives. In the present investigation neutron diffraction is used as a non-destructive technique for the evaluation of through thickness variations of residual strains in welded test samples of steel plates. The neutron diffraction strain measurements show relatively high residual strains reaching + 1 × 10−3 near the outer surfaces and −4 × 10−4 near the centre of the plates. A simplified strain/stress conversion indicates that the highest residual stress exceeds approximately 50% of the material yield stress of σy ≈ 400 MPa.