Neutron diffraction and finite element modeling to study the weld residual stress relaxation induced by cutting

Abstract

Temperature and residual stresses were thermo-mechanically modeled in a 1000mm long welding plate based on the simplified variable length heat source. The stress relaxations were simulated as a function of the plate length after cutting the initial weld specimen by using an element removal method and treating the prior stress field as the next cutting origins. Meanwhile residual stresses were sequentially measured in a weld with the length of 300mm and cut welds having 150, 10mm lengths for comparison using neutron diffraction. Residual stresses from both the modeling and experimental results exponentially decrease from about 370 to 0MPa as the total weld plate length decreases from 300mm to 10mm. Such stress relaxation by the cutting length is correlated to the exponential decrease law based on the St. Venant’s principle. It suggests that the minimum cutting length about 300mm is necessary to prevent the stress relaxation less than 3% of the initial stresses in a high-strength steel weld.