Xl. Wang et al., EXPERIMENTAL-DETERMINATION OF THE RESIDUAL-STRESSES IN A SPIRAL WELD OVERLAY TUBE, Materials science & engineering. A, Structural materials: properties, microstructure and processing, 232(1-2), 1997, pp. 31-38
Neutron diffraction was used to determine the residual stresses in a s
piral weld overlay tube. The specimen was a 2.5 in. OD carbon steel tu
be covered with a layer of alloy 625 weld overlay. Residual strains in
the carbon steel and weld overlay layers were determined using the fe
rritic (211) and austenitic (311) reflections, respectively. The resid
ual stresses in each material were derived from the measured strains u
sing Hooke's law and appropriate elastic constants. Tensile stress reg
ions were found not only in the weld metal but also in the heat-affect
ed zone in the carbon steel. The maximum tensile stress was located in
the weld overlay layer and amounted to 360 MPa, about 75% of the 0.2%
yield strength of the weld metal. The experimental data were compared
with a finite element analysis based on an uncoupled thermal-mechanic
al formulation. Overall, the modeling results are in satisfactory agre
ement with the experimental data, although the hoop strain (stress) se
ems to have been overestimated by the finite element model. Additional
neutron diffraction measurements reveal that these welding residual s
tresses vanished after annealing at 900 degrees C for 20 min. (C) 1997
Elsevier Science S.A.