Martensitic transformation as an analogue of a detonation process

Abstract

The paper deals with the wave model of an austenite to martensite transformation in steel, which is an analogue of a shockwave 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 ρ a = 8000 kg / m 3 and martensite density ρ m = 7750 kg / m 3 , 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.Keywords: detonation, shock adiabat, martensite, austenite. Мартенситное превращение как аналог детонационного процессаАлымов М.И., Трофимов В.С. † , Петров Е.В. † pnkv@list.ru ФГБУН Институт структурной макрокинетики и проблем материаловедения РАН, ул. Академика Осипьяна 8, 142432, Черноголовка, Россия В работе рассматривается волновая модель протекающего в стали превращения аустенита в мартенсит как аналог ударно-волнового процесса, подобного детонации, при котором волна превращения аустенита в мартенсит распро-страняется вдоль бруса стали. В монографии Кащенко М. П. развивается волновая модель, согласно которой, по край-ней мере, внутри отдельных зерен аустенита это превращение протекает в виде волн, движущихся со сверхзвуко-вой скоростью. В данной работе по нашим оценкам, при данном превращении аустенита в мартенсит выполняется известный критерий детонационной способности. При нормальных условиях плотность аустенита ρ a = 8000 кг / м 3 , плотность мартенсита ρ m = 7750 кг / м 3 , следовательно превращение аустенита в мартенсит при постоянных давлении P = 10 5 Па и температуре T = 300 K приводит к увеличению объема стали. При этом выделяется удельная теплота Q P,T = 82 × 10 3 Дж / кг. Следовательно, на основании этих данных легко приходим к выводу, что если бы данное превра-щение удалось реализовать в крупном брусе стали, то оно протекало бы в виде детонации, то есть в виде движения со сверхзвуковой скоростью волны физико-химического превращени...

Molecular dynamics simulation of the effect of dislocations on the martensitic transformations in a two-dimensional model

“…However, the consideration of the effects of SM and superelasticity is not prohibited in frame of this model, since the degree of coherence of the martensite and austenite lattices is quite high. One of the important problems for futher investigations is the studying of the MT as the detonation process [36].…”

Deformation and fracture of porous iron under dynamic loading

“…In addition, the appearance of adiabatic shear bands (figure 4b) and partially fragmented structures (figure 4b) should be noted. By analogy with the works [19 -24], it can be assumed that the emerging martensite crystals at a supersonic speed penetrate the grain volume, forming perturbation fronts, some of which overtake the shock wave that initiated the transformation, i.e., in fact, we have a certain analogy with detonation process [24]. In this case, the supersonic velocity of the martensitic transformation is analogous to the velocity of the detonation wave D. In the first approximation, we define this velocity.…”

Features of Deformation and Fracture of Porous Iron under Submicrosecond Loading

“…By analogy with the works [19][20][21][22][23][24], it can be assumed that the arising martensitic crystals penetrate the grain volume at supersonic speed, forming perturbation fronts, some of which overtake the shock wave that initiated the transformation, i.e., in fact, we have a certain analogy with the detonation process [24]. In this case, the supersonic velocity of the martensitic transformation is analogous to the velocity of the detonation wave D. In the first approximation, we will define this velocity.…”

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