The calculation of Tδ and Vδ in austenitic steel

The relation between the γ/γ + δ boundary temperature, Tδ, of austenitic steels and the equivalent weights, [Cr] and [Ni], has been studied, as has the law of variation of the δ phase volume, Vδ, with temperature. With the aid of a computer, the following regression expressions have been derived from the experimental results: Tδ (°C) = T4 − 21.2[Cr] + 15.8[Ni] − 223 Vδ (%) = 0.715 exp [0.015(T − Tδ)] Satisfactory results have been obtained by using these regression expressions.