Nature of the increase in the strength of austenitic cast irons with spheroidal graphite after the????? transformation

Abstract

1. The high strength of austenite, the relief formed after the reverse α→γ transformation, the lowering of Ms, and the structural characteristics of the austenite point to the displacement martensitic mechanism of the reverse α→γ transformation in high-nickel cast irons with spheroidal graphite. 2. The increase in the strength of the cast irons after the cold treatment and reaustenitizing is the result of combined phase strain hardening of austenite due to the martensitic γ→α→γ transformation and precipitation hardening as the result of carbide precipitation. 3. Preliminary aging of austenite and the subsequent γ→α→γ treatment make it possible to increase the yield strength by a factor of 2–2.5 for high-nickel austenitic cast irons, with retention of low permeability.