Residual Stress Distribution in Carbon Steel Pipe Welded Joint Measured by Neutron Diffraction

概要

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In order to estimate crack growth behavior of fatigue and stress corrosion cracking in pipes, the residual stress distribution near the pipe weld region has to be measured through the wall thickness.Since the penetration depth of neutron is deep enough to pass through the thick pipe wall, the neutron diffraction technique for the residual stress measurement is effective for this purpose.At the first step the residual stress distribution near the weld region in a butt-welded carbon steel pipe was measured by the neutron diffraction.Significant stresses extended only to a distance of 30mm from the center of the weld.The major tensile stresses occurred in the hoop direction in the fusion and heat affected zones of the weldment, and they attained a level greater than 200MPa through the thickness.While the axial residual stress at the inside surface was 50MPa, the stress at the outside surface was-100MPa.The comparison of residual stress distributions measured by the neutron diffracion, the X-ray diffraction and the strain gaugemethod reveals that the neutron diffraction is the most effective for measuring the residual stress inside the structuaral components.
社団法人日本材料学会の論文
2000-12-15