Effect of the austenite stability on the fracture mode and mechanical properties of aging nonmagnetic alloys after different strengthening treatments

Aging austenitic alloys with a stable (N26Kh5T3; M _s < −196°C) and metastable (N25Kh2T3; M _s = −130°C) austenite have been investigated after employing different methods of heat and thermomechanical treatments, namely, (1) aging at a temperature T _a = 600°C (A); (2) strengthening using phase-transformation-induced hardening (“phase naklep” (PN)) and subsequent aging at T _a = 600°C (PN + A); (3) deformation to 30% (D) at T _d = 600°C after preliminary aging at the same temperature (A + D); and (4) PN + A + D. In this case, the alloy with stable austenite has not been strengthened by phase naklep. Structure, fracture mode, ultimate strength, yield strength, relative reduction of area, and relative elongation have been studied depending on the duration of aging τ_a upon these strengthening treatments. It has been established that the physicomechanical properties of the alloys depend not only on τ_a, but also on the testing temperature. It is shown that all above physicomechanical characteristics of the alloys under consideration are affected substantially by the austenite stability.