Following the publication of a first set of four volumes of SGTE compiled thermodynamic properties of inorganic substances, which dealt with pure substances (Subvolume A) and a second set of five volumes with selected thermodynamic data for binary alloy systems (Subvolume B), this set of volumes focuses on data for ternary systems for one vitally important specific class of materials, steels. Various diagrams for each system are presented, calculated from a specially developed SGTE database for steels. Background information is also presented for each system. The fundamental equations used in evaluating the data are given in the introduction to the volumes and the models used in representing the data are also described.For this volume a steel database has been compiled, consisting of 11 elements: Fe, C, N, Cr, Mn, Mo, Ni, Si, Ti, V, and W. With this selection of elements a broad range of steels and cast irons is covered. The database allows not only calculations within the included assessed systems but it is also capable of interpolating into regions which are not well-known. Typical steel databases are confined to the Fe-rich corner. Contrary to that the present compilation covers the composition range of all evaluated systems as much as possible.