Residual Gas Degassing Kinetics
Time-dependent diffusion of dissolved gases such as hydrogen or nitrogen out of the metallic matrix under modified pressure and temperature conditions. It determines the necessary holding time during bake-out and stress-relief annealing.
During welding and heat treatment, the goal is to allow dissolved gases – especially hydrogen – to escape from the material. If you cool the metal too quickly or choose too short a soaking time, the gases remain trapped and cause stresses, cracks, or deformations. So give the material enough time during annealing to degas properly. Depending on the material and wall thickness, you need to adjust the holding time – when in doubt, rather anneal longer than too short. A steel that degasses cleanly is half the battle for a crack-free weld.