This paper presents a dynamical non linear model of the
spatial time-dependant evolution of A3 point during a particular
sequence of resistance spot welding in steel material. The model is based on
a solution to the heat equation, expressed in cylindrical coordinates inside
the joint area, and when the source term is attributed to the electrical
power. By the mean of the steel binary Fe–C diagram and the deduced
t-dependant temperature rise profile, an estimation of the A3 point
spatial range date is given and compared to further results. The obtained
temperature profile is yielded, taking into account main parameters
variations, as a guide to non-destructive protocols and thermal
characteristics investigation