Test on residual stress of high strength Q960 steel welded H- and box-sections after exposure to high temperature

Residual stress can lead to premature yielding in specific regions of a component when subjected to load. During a fire event, a steel structure experiences strength loss and creep deformation, which will release the residual stresses formed during the welding process. Therefore, in order to accurately assess the bearing capacity of a steel structure after a fire, it is crucial to consider the effect of residual stress, which necessitates the measurements of the residual stresses after exposure to high temperatures. For this purpose, three H-sections and three boxsections were fabricated, and the residual stresses of these sections were measured using the sectioning method. The magnitude and distributions of two cross-section specimens' residual stresses were measured at 3 conditions: ambient temperature, exposed to 600 degrees C and 800 degree celsius. The findings indicate a reduction in the residual stresses of the specimens subjected to heating at 600 degrees C and 800 degrees C compared to those at ambient temperature, with the decrease being more pronounced at higher temperatures. The distributions and magnitudes of the residual stress in high-strength Q960 steel welded H-section and box-section after high temperatures are formulated based on the test results. Comparing the test results with the existing residual stress reduction formula, it is found that the formula has good applicability to the reduction coefficient of welding residual stress of high strength Q960 steel after high temperature.