Thermal loadings representative of a welding cycle at a point in the Heat Affected Zone (HAZ) of an Electron Beam Welding (EBW) have been reproduced experimentally. It means that the temperature is continuously varying, first increasing (during heating) and then decreasing (during cooling) without dwell-time at the highest temperature. Tensile tests have been carried out either during heating or during cooling of the specimen. The mechanical properties of two idealized phases - T6 temper and O temper - have been estimated as a function of temperature. To validate the accuracy of this thermo-mechanical database, a comparison between measured and calculated stress-strain curve is then presented which shows that this approach may be useful to predict the tensile behaviour of this alloy at high temperature whatever the experienced temperature history representative of EBW. Finally, a comparison between numerical and experimental residual stresses is presented for a beam girth weld application.