Surface solidification with a moving heat source: A study of solidification parameters

Abstract

The heat flow and solidification parameters, such as the temperature gradient and solid-liquid interface velocity, have been studied for the case of a moving heat source on an aluminium substrate. The problem was developed and solved for both the large initial transient and the final quasi steady state. Results indicate that exceptionally high temperature gradients may exist in the liquid pool. During the initial transient, the temperature gradient at the solid-liquid interface drops from a high value to a low one at a near constant interface velocity. These results are expected to aid in the design of solidification experiments. The predictive capacity of the model was tested by measuring the secondary dendrite arm spacing (SDAS) along the region of the initial transient on the surface of a Al-4.5% Cu alloy laser treated with a 5 kW laser. Results obtained showed the SDAS increasing to a steady state value only after the melt width had achieved a steady state, thus validating the theoretical conclusions of the model.