Eddy-Current Studies of Aging Processes in N26T3 Metastable Austenite Steel

In the N26T3 austenite steel, the eddy-current parameter f0 has been measured after one aging cycle at temperatures of 700 and 650°C, and after two aging cycles, one of them at the same temperature and the second at 600 and 550°C. The two-stage aging is conducted by two schemes: (1) preliminary aging at 700 or 650°C, transfer of samples without cooling to the room temperature into a furnace heated to 600 or 550°C, then isothermal aging and cooling to room temperature Tr; (2) the same operations as in the first scheme, but the samples are cooled to Tr after the preliminary aging. The eddy-current parameter f0 measured at Tr increases with time after aging at 700 and 600°C owing to isothermal γ → α martensite transformation. After the two-stage aging, the isothermal martensite transformation at Tr still takes place, but it is stabilized, i.e., the parameter f0 drops with time. The stabilization of the austenite is the more pronounced, the lower the temperature of the second stage of aging, and it is stronger after the two-stage aging by the second scheme.