Accuracy Validation of Measurement of Transient Thermal Stress at Steel Welds by Synchrotron X-ray Diffraction Techniques

Abstract

An advanced welding thermal elastic-plastic analysis, which has recently been developed by authors to improve both accuracy and reliability of welding simulation techniques, was applied to validate the measurement of transient thermal stress at steel welds by synchrotron X-ray diffraction techniques. The calculated weld penetration, temperature profiles, the transient thermal stress and distribution of residual stress at welds were compared with those measured. The results showed that there were, on the whole, comparatively good agreement between the calculations and experimental values. However, an obvious discrepancy between the calculations and experimental values can be seen in the variation behavior of stress during cooling process after welding only at weld metal (WM) and heat-affected zone (HAZ). It was thought to be due to phase transformation induced by welding. This discrepancy provides one of prospects for the future that X-ray elastic constants vary according to microstructure evolution is essential to accurately estimate the transient thermal stress and residual stress at steel welds with phase transformation. It is then expected that dependence of X-ray elastic constants on the microstructure with phase transformation is clarified more clearly.