John N. Dupont
Welding is one of the most complicated fabrication processes used to assemble engineering structures. The process involves heating and cooling rates that are significantly higher than most manufacturing processes, and the materials are subjected to a wide range of peak temperatures that span from ambient to above the liquidus temperature. As a result, the base materials can undergo a wide range of solidification and solid state phase transformations that will induce significant changes to the pre-existing microstructure and associated properties. Due to these extreme conditions, the phase transformations usually occur under non-equilibrium conditions and often produce unexpected microstructures that have detrimental effects on properties.