Мартенситное превращение как аналог детонационного процесса

Abstract

The paper deals with the wave model of an austenite to martensite transformation in steel, which is an analogue of a shock-wave process like detonation where a wave of transformation of austenite to martensite steel propagates along a steel beam. In Kashchenko’s monograph a wave model has been developed according to which, at least within individual austenite grains, this transformation takes place in the form of waves moving at a supersonic speed. In the present work, according to our estimates, the known criterium of detonation capacity is fulfilled in the process of austenite to martensite tranfromation. Under normal conditions, austenite density equals ρa = 8000 kg/m3 and martensite density ρm = 7750 kg/m3, therefore the transformation of austenite to martensite at constant pressure P = 0.1 MPa and temperature T = 300 K results in an increase of the volume of steel. This releases a latent heat Q(P,T) = 82000 J/kg. Therefore, based on these data one can conclude that if this transformation is implemented in a large steel beam, it would take the form of detonation, that is, a motion at a supersonic velocity of a physical-chemical transformation wave, in this case in the form of a wave of phase transition from austenite to martensite. Parameters of such a process for different ratios between the masses of the austenite and martensite steel in the original beam are estimated. The results of theoretical calculations of the parameters of detonation waves in steel at different weight ratios between austenite and martensite steel in the original beam are presented.