The transition from gray to white cast iron during solidification: Part III. Thermal analysis

Abstract

In Part I of this work, an analytical model was derived based on the theory for the transition from gray to white cast iron during solidification. Accordingly, in this part of the work, analytical expressions were found that can be related to the chill width in wedge-shaped castings (or the critical pin diameter and critical wall thickness below which the chill is expected) with temperature parameters that are commonly measured by thermal analysis. Among these parameters are ΔT _c =T _m −T _c and ΔT _sc =T _s −T _c , where T _m is the minimal solidification temperature for graphite eutectic, T _c is the transformation temperature for cementite eutectic, and T _s is the equilibrium solidification temperature for graphite eutectic. In particular, it was found that the analytical model agrees well with the experimentally measured temperatures. Measured values from thermal analysis for the excess-temperature range (ΔT _c ) and of the ΔT _c /ΔT _sc ratios were found to be in good agreement with the theoretical predictions for the chill of cast iron. In addition, it was found that the predictions from the proposed analytical expressions are similar to those obtained from statistical analyses of the experimental outcome.