Evaluation of the equivalent time of non-isothermal diffusion processes in the heat-affected zone in fusion welding

Abstract

A technique for transforming an anisothermic diffusion problem (when the diffusion coefficient is not constant) into an isothermal problem (when the diffusion coefficient is constant) is proposed. It is based on the equivalent time concept. The interrelation between equivalent time and real time is established. The technique enables one to use the known analytical solutions of the linear diffusion problems. It is shown that preheating intensifies carbon diffusion in the heat-affected zone.

Keywords:

• anisothermic diffusion process
• diffusion coefficient
• equivalent time
• carbon