OS04W0182 Neutron diffraction study of residual stress in the induction hardened S45C round bar

Abstract

The thermal residual stress at the internal positions of central circular sectional plane of an induction hardened S45C round bar was measured nondestructively by neutron diffraction. The neutron diffraction equipments, RESA installed at JRR-3M reactor and Sirius at KENS were used. We observed the SEM image of the sliced specimen cut from the round bar to investigate the existence of martensitic phase. The sliced specimen was also used for the determination of the stress free lattice spacing in the case of coexistence of martensitic phase and ferritic phase. The Young's modulus and the Poisson ratio were obtained by the neutron diffraction of the specimen for tension test. As a result, the residual stress for radial direction at the surface of the bar is nearly equal to zero, and those for hoop and axial directions are near -900 MPa, which is largely compressive. These three stresses gradually increase to tensile one as we approach the center of the sectional plane. These results show a good coincidence with the result of FEM analysis.