Neutron diffraction measurement and finite element method calculation of residual stress of a heat treated steel pipe

The residual strain of a 13% Cr steel pipe for use in oil wells was measure d by neutron diffraction. As the pipe was quenched from 900 degreesC to roo m temperature by spraying water at 30 degreesC on the outer surface of the pipe for 30 s, it should be exposed to thermal stress. To measure the strai n in the pipe, the residual stress analyzer (RESA) using neutron diffractio n at Japan Research Reactor No. 3 Modified (JRR-3M) was used. Three directi onal measurements were carried out at intervals of 1 mm for the wall thickn ess of 5.51 mm. The residual stress deduced fr om the observed strain showe d that the stress in the axial direction was tensile near the outer surface and compressive near the inner surface. The deduced stress was compared wi th the stress calculated by the finite element method (FEM).