Application of Schaeffler Diagram for Predicting the Structure and Mechanical Properties of Heat-Resistant Steels with More than 10 wt.% Cr

An overview of the most used variants of the structural-chemical Schaeffler diagram developed by various researchers is presented. A new version of the Schaeffler diagram and equations for calculating Cr- and Ni-equivalents are suggested, which makes it possible to correctly predict the content of δ-ferrite in the structure of heat-resistant ferritic–martensitic steels of the EP450 – EP823 – EK181 – ChS139 group containing ≥ 10 wt.% Cr, after hot deformation and heat treatment. Based on the factor analysis of the relationship between the physicochemical and structural characteristics of such steels and their mechanical properties, equations are obtained in which the Cr- and Ni-equivalents are allowed for as factors determining the value of the yield strength.