Investigation of Microstructural Changes after Solution Annealing Treatment in a Duplex Stainless Steel

This work investigates the microstructural changes developed during the solution annealing treatment under different conditions for the steel UNS S31803. The studied material was submitted to solution anneal at 1100°C for 30, 120 and 240 min, followed by cooling in water, air and furnace. The results evaluation was based on micrographic analysis and the results showed the influence of treatment period and cooling rates in distribution and morphology of austenitic phase. It was observed the same morphology of austenitic phase in all treatment conditions, however, the volume fraction of this phase increased with the treatment period increase, and further refinement with lower cooling rates. It was found that the solution treatment by longer period with the lower cooling rate significantly enhanced the intermetallic phases transformation. The intermetallic phases precipitation could be detected when the samples were solution-treated for 120 and 240 min and cooled at furnace.