Solid materials property data are an important basis for optimization of products and production processes. Traditional testing of materials usually requires great efforts and is also time consuming. Calculations of thermal, physical and materials properties using JMatPro (on the example of 42CrMo4 steel) can close the resulting gap — a practical application in the steel plant of Georgsmarienhütte GmbH is shown. Electric arc furnace of this works is characterized is supplied by modern systems for heat and gas recovery and environment protection facilities. Average fluidity curves of liquid metal are analyzed via finite element method on the base of JMatPro are built.