Investigation of Phase transformaton Kinetics and Microstructural Evolution in 1045 and 52100 Steel under Large Magnetic Fields

Abstract

Magnetic fields varying from ambient to 30 tesla were applied during austenite decomposition in 1045 and 52100 steels. Thermal recalescence due to the release of latent heat during austenite decomposition is observed in temperature measurements and provides an estimate of transformation temperatures. Microstructural analysis was performed using and electron microscopy along with microhardness measurements. The shift in transformation temperature was estimated at 3°C/tesla which corresponds to an apparent free energy shift of 12.6 J/mol/tesla in 1045 steel. This shift in transformation temperature was accompanied by an increase in ferrite content. In 52100 steel, the magnetic field altered the transformation product from martensite to pearlite for a single cooling rate. This result indicates that the transformation mechanism can be selected by an applied magnetic field for a fixed cooling rate and alloy chemistry.