ANALITYCAL METHODS FOR THE ANAYSIS OF PHASE TRANSFORMATIONS IN SOLID STATE OCCURING DURING WELDING

Analytical models used for the analysis of phase transformations as well as the prediction of structural composition of welded elements are the subject of research for many years. Despite of certain simplifications they are invaluable in assessing the weldability and welding conditions. Results obtained by analytical methods are often used for the initial analysis of the material properties prior to the experimental studies and used before developing of mathematical models. The paper presents an analysis of phase transformations in solid state during welding of S460 steel. Empirical relations are given with the cooling rates taken into consideration, on which start and finish temperatures of bainite, ferrite pearlite, and martensite transformation are determined. Obtained data allowed predicting different start and finishing temperatures of phase transformations for various cooling rates v(8/5) (t(8/5)). Analytical Continuous-Cooling-Transformation (CCT) diagram for steel is determined as well as volume fractions of phases in a function of cooling rates. Analytically obtained results are compared with experimental data obtained by dilatometric tests.