Numerical calculation and experimental measurement of temperatures and welding residual stresses in a thick-walled T-joint structure

In this investigation, a T-joint numerical welding simulation of thick steel plates is performed to estimate transient temperature distributions, residual stress field and model deflections. A sequential simulation method is applied in the numerical simulation, where the thermal analysis is done by using the EBD technique to simulate the weld wire melting and metal filler addition while the mechanical analysis is performed in one step without EBD to shorten the calculation time. Thermocouples, non-destructive X-ray diffraction and semi-destructive hole-drilling methods are used to measure the temperature and residual stress distributions. In the thermal analysis, a simplified heat flux is used which causes a relatively large temperature discrepancy in the weld pool area between the numerical and experimental results. The calculated temperature histories outside the weld pool and its vicinity correlate very well with the experimental measurements with an acceptable discrepancy of approximately 4%. The residual stresses are firstly measured on the model surface without electropolishing and then two times after that, at depths of 0.005 and 0.015 mm. The results of residual stress obtained by numerical modelling and measurement with X-ray agree better when the electropolishing removing layer is set to 0.015 mm, due to a significantly smaller effect of surface conditions that originate from steel plate production.