In this paper we present a new polynomial function for calculating the local phase transformation temperature (Ae3 ) between the austenite+ferrite and the fully austenitic phase fields during heating and cooling of steel:[Formula: see text] The dataset includes the terms of the function and the values for the polynomial coefficients for major alloying elements in steel. A short description of the approximation method used to derive and validate the coefficients has also been included. For discussion and application of this model, please refer to the full length article entitled "The role of aluminium in chemical and phase segregation in a TRIP-assisted dual phase steel" 10.1016/j.actamat.2016.05.046 (Ennis et al., 2016) [1].