The predecomposition condition of supercooled austenite

Conclusions

• 1. It was shown experimentally that decomposition of supercooled austenite begins almost immediately on reaching the temperature below which the austenite becomes metastable. The precipitation of small amounts of decomposition products is due to mechanical stabilization of supercooled austenite, which is evident in the fairly rapid slow down of decomposition. The development of thermal stabilization is indicated by the relationship between the isothermal holding temperature and the amount of decomposition products required for the development of mechanical stabilization; in accordance with the data given in [14], the degree of thermal stabilization increases with the temperature.

• 2. It is probable that concentration fluctuations develop during isothermal holding, which absorb some amount of strain energy during deformation of the material that is sufficient for rebuilding of the lattice and creation of an interface, as the result of which particles of ferromagnetic phase are precipitated in slip systems. A substantial portion of this phase is unstable after removal of the stress field and is dissolved during further isothermal holding.

• 3. The development of mechanical stabilization due to precipitation of decomposition products is also evident in the fact that decomposition of deformed austenite lags behind the decomposition of undeformed austenite.