σ phase dissolution in duplex stainless steel at elevated temperature studied by thermal analysis

The redissolution of sigma phase to ferrite in duplex stainless steel (DSS) in high temperature range was studied by differential thermal analysis (DTA) and scanning electron microscopy. DSS samples were aged at different temperatures for various durations. The conditions were chosen such that all the ferrite transformed to sigma phase. Subsequent DTA measurements revealed that the onset temperature T-s and the peak temperature T-p for sigma dissolution strongly depend on the initial distribution and the morphology of sigma phase. This correlation between the DTA characteristic temperatures and prior ageing temperatures may be used for temperature indication purposes in applications involving hostile environments. (C) 2008 Elsevier B.V. All rights reserved.