Numerical prediction and neutron diffraction measurement of the residual stresses for a modified 9Cr–1Mo steel weld

A modified 9Cr–1Mo steel provides extremely good mechanical properties at a high temperature when produced and heat treated, and thus the interest in the weld characteristics of a modified 9Cr–1Mo steel is increasing due to its potentiality for an application to modern power plants and advanced reactor systems. For the design and fabrication of stable welded structures, the effects of residual stress and deformation need to be estimated. The objective of this paper is to compare the measured residual stresses for modified 9Cr–1Mo steel welds induced by welding processes and the predicted residual stresses by a numerical simulation. The neutron diffraction technique is used to measure the residual stresses both on the surface and in the interior of a thickness for the welded specimens. A T-plate specimen and a V-butt specimen are prepared and their residual stresses are measured. A finite element model is employed to calculate the transient temperature and the residual stresses. The measured data and the simulation results are compared and the characteristics of a distribution of the residual stresses are discussed.