The Driving Force for Lath and Plate Martensite and the Activation Energy for Isothermal Martensite in Ferrous Alloys

A. Borgenstam, M. Hillert
1997 Journal de Physique IV : Proceedings  
From information on M, for lath and lenticular martensite the driving force for the start of a formation of the two types of martensite was calculated in a number of Fe-X systems. By plotting the calculated driving force against temperature the results indicate that the driving force for formation of martensite may not be much affected by solution hardening but mainly be a function of temperature. From the kinetics of isothermal a martensite in ferrous alloys one can clearly distinguish between
more » ... two groups of alloys, high alloy steels and carbon containing steels. High alloy steels with low M, temperature have a temperature dependence corresponding to a very low activation energy, possibly 7 kJ/mol. -It can hardly depend on any diffusion process. Carbon containing steels have a temperature dependence corresponding to an activation energy of about 80 kJ/mol. Its rate of formation can be explained by assuming that it is triggered by submicroscopic plates of bainite formed with a rate of carbon diffusion.
doi:10.1051/jp4:1997503 fatcat:aopayomexvcptp2yvzwa3mg2xi