Aging of a metastable austenitic steel N26T3 with the initial structure ofdiscontinuous precipitation

The structure and strength of the N26T3 alloy with the initial structure of discontinuous precipitation (SDP) were studied after treatments by two reg imes: (1) cooling of the samples with a two-phase SDP (eta + gamma) in liqu id nitrogen to ensure the formation of a three-phase structure consisting o f intermetallic (eta), austenitic (gamma), and martensitic (alpha) phases a nd (2) the same plus heating to 800 degrees C and holding for 5 min to ensu re the realization of the reverse alpha --> gamma(ph) martensitic transform ation. Before and after these treatments, the samples with an SDP were aged at 20-800 degrees C for 1 h. Heating to T-a greater than or equal to 400 d egrees C causes aging of the martensite and increases hardness by 27%, whos e maximum is reached at T-a = 500 degrees C. Aging of the samples with the eta + gamma SDP does not increase hardness, and the substitution of the tra nsformation-hardened (reverted) austenite gamma(ph) for the initial austeni te (treatment by regime 2) increases hardness by a factor of two. Aging of the reverted austenite at T-a = 600 degrees C additionally increases hardne ss of the samples with SDP by more than 30%.