Residual Stress Evaluation of Quenched Steel by Neutron Diffraction Measurement and Phase Transformation Analysis
Ryuji MUKAI, Dong Yong JU, Nobuaki MINAKAWA, Yukio MORII and Atsushi MORIAI
Abstract:Neutron diffraction method is employed to measure the residual stress inside of quenched steel. To determine the residual stress, it is necessary to know the non-distortion lattice spacing and elastic constant of the material depending on gradient distribution of microstructure and carbon content. In this paper, metallo-thermo-mechanical simulation by finite element method is performed to estimate the distribution of martensite phase and carbon content. Non-distortion lattice spacing, Youngfs modulus and Poissonfs ratio were measured in order to measure the residual stress of test piece of quenching. These values are decided by the distribution of carbon content and martensite phase. After that, the residual stresses in cylinder specimen of quenched S45C and SCr420 steel are measured by the neutron diffraction method. In addition, the measured results of XRD, neutron diffraction as well as calculated value are compared and discussed. As the result, the non-distortion lattice spacing depend on martensite phase are verified. It is feasible to evaluate the residual stress inside of the quenching material combing with measured results and simulation values. Key Words:Residual stresses, Neutron diffraction, Quenching, Phase transformation, Finite element method, Coupling analysis