A Calorimetric Study of Recovery and Recrystallization in Fe–14.4 Cr–15.4 Ni–2.4 Mo–2.36 Mn–0.25 Ti–0.04 C–0.05 P (mass %) Austenitic Stainless Steel. Issue 10 (24th May 2013)

• Record Type: Journal Article
• Authors: Tripathy, Haraprasanna; Raju, Subramaniam; Rai, Arun Kumar; Jayakumar, Tamanna
• Is Part Of: Steel research international. Volume 84:Issue 10(2013:Oct.)
• Page Start: 1046
• Page End: 1059
• Publication Date: 2013-05-24
• Subjects: austenitic steel -- stored energy -- differential scanning calorimetry -- coldwork -- recovery -- recrystallization; Steel -- Periodicals; Steel -- Metallurgy -- Periodicals; 669.142
• DOI: 10.1002/srin.201300002
• Languages: English
• ISSNs: 1611-3683

Abstract

Abstract: The stored energy release and the kinetics of recovery and recrystallization processes in 70 and 85% coldworked nuclear grade austenitic stainless steel have been investigated by dynamic calorimetry, the results of which are supplemented by optical microscopy and microhardness measurements. Distinct thermal arrests arising from recovery and recrystallization events that occur upon slow heating are around 815 and 1070 K, respectively. The peak recovery and recrystallization temperatures are found to be sensitive to prior coldwork and heating rate. Faster rates of heating pushed the recovery stage to higher temperatures overlapping with the domain of recrystallization, which resulted in a decreased dissipation of stored energy due to recovery. As a result, faster heating rates, served to accelerate the kinetics of recrystallization owing to higher driving force. It is also found that the dissolution of fine TiC particles lead to secondary recrystallization at higher temperatures. Modeling of lattice softening kinetics yielded values of effective activation energies for recovery and recrystallization processes in the range, 198 and 336 kJ mol −1, respectively. Abstract : Thermally activated dissipation of stored energy and resulting microstructural reorganization of a Ti‐added steel have been monitored by dynamic calorimetry. The studies revealed that the kinetics of stored energy release and resulting structure formation is basically a dispersive one, involving more than one relaxation time. However, it is possible to isolate the energy barriers for recovery and recrystallization stages by modeling the rate of energy dissipation through isokinetic formalism of thermally activated rate processes.