Temperature A comparison between the temperature profile and heating rate extracted from the models at the end of conditioning is presented in Fig. 9. It can be seen that the higher axial load applied to Weld 2 results in a higher peak temperature of around 100◦C at the inter-face along with a far higher heating rate close to the interface, while further away from the weld interface (>5 mm), as a result of the longer conditioning period of Weld 1 (1.5 s vs the 0.75 s of Weld 2)due to the reduced energy input rate caused by the lower pressure meaning the material close to the interface requires a longer time to reach the forging temperatures required for the deformation to begin (end of conditioning), the conduction effects dominate and the heating rate is higher in this region.