The study presents the results of research aimed at the construction of a model of the relationship between the physical properties of metal and the types of toughening treatment and modifiers used in the modification of BA1044 alloy. Samples of melts were subjected to four variants of the heat treatment and to five types of modification. Studies of the samples consisted in measurements of five physical parameters. Consequently, it was necessary to seek a relationship between the nine input parameters and five output parameters. With this number of the variables and a limited number of samples, searching for the relationships by way of statistical methods was obviously impossible, so it was decided to create an approximate model through the use of fuzzy logic. This study describes the process of creating a model and presents the results of some simulation experiments that confirm the validity of the correct approach.