Dilatometric and Hardness Analysis of C45 Steel Tempering with Different Heating-up Rates

Modelling of technological processes of heat treatment or welding, involving multiple heat source transitions, requires considering the phenomenon of tempering. In work have been presented results of dilatometric research of hardened C45 steel subjected to tempering. The analysis of the infl uence of heating rate at the kinetic determined from dilatometric curves has been made. There have also been estimated quantities of transformation expansions and thermal expansion coeffi cients of hardening and tempering structures (austenite, ferrite, pearlite, martensite and sorbite). The analysis of tempering time infl uence on the hardness of tempered steel has been made. Functions associating hardness with tempering time (rate of heating-up) in technological processes based on short-timed action of a heat source (eg. laser treatment) have been suggested.