Critical comparison of two independent measurements of residual stress in an electron-beam welded uranium cylinder: Neutron diffraction and the contour method

Abstract

Neutron diffraction and contour method measurements were conducted to assess the stresses associated with an electron-beam, circumferential, partial penetration weld of a uranium tube. To obtain reasonable results in the coarse-grained base metal, the specimen was continuously rotated during the neutron experiments to average over the entire circumference. The severe anisotropic character of uranium, which has an orthorhombic crystal structure, forces a number of judicious choices to be made in the neutron analysis. For the contour method, the cylindrical geometry necessitated the development of a two-step process, and discontinuities across the unwelded portion of the joint required special treatment. High tensile hoop stresses (∼300 MPa) were found in the center of the weld close to the outside diameter. Balancing hoop compression was observed in the far-field stress profile. Also, a tensile axial stress (85 ± 25 MPa) was observed near the outer diameter.