Modeling Short Time Dilatometry Testing of Some 0.55% Carbon Steels

Dilatometry test systems are commonly used for characterizing the transformation behavior in steels and induction heating is commonly the heating source.  In these systems, the steel test article is assumed to have a uniform temperature throughout the sample.  This is a good assumption for slow heating rates with small samples, however, for induction hardening cycles this may or may not be accurate.  Using computer models, it is possible to predict the temperature dynamics of the sample, both radially and axially, during the thermal processing cycle (heating and cooling). 

The current modeling study will be used in conjunction with experimental trials conducted on laboratory melted steels containing 0.55 wt% C that were preconditioned by austenitizing at 900 ^oC and oil quenching. The oil quenched specimens were induction heated rapidly and the hardenability was determined for austenitizing times of 2 and 10 s.  The progression of transformation to austenite on heating was determined by metallographic examination of specimens quenched from several peak heating temperatures.  The quench rate required to attain fully martensitic microstructures increased as the austenitizing time was reduced.  The goal of the modeling is to better characterize rapid heating and cooling processes when determining transformation behavior in induction hardenable steels.