Strength and Relaxation and Corrosion Resistance of Ultrafine-Grained Austenitic 08Kh18N10T Steel Produced by ECAP: III. Deformation Behavior at Elevated Temperatures

Abstract—The deformation behavior of an ultrafine-grained (UFG) 08Kh18N10T steel at elevated temperatures (450–900°C) has been studied. The maximum elongation to failure (~250%) is detected at a temperature of 750°C. The deformation of the UFG steel at elevated temperatures is controlled by the intensities of simultaneous processes of grain-boundary sliding and power-law creep. The contribution of each mechanism depends on the grain growth rate under superplasticity conditions, which affects the rate of defect accumulation at migrating grain boundaries. The fracture of the UFG steel has a cavitation character: the fracture and specimen surfaces after high-temperature tests contain large elongated pores having formed on nonmetallic inclusions and submicron pores having formed on σ-phase particles.