Influence of thermomechanical treatment on the grain-growth behaviour of new Fe-Al based alloys with fine Al2O3 precipitates

To obtain the superior-high-temperature creep strength, a transformation of a fine-grained structure to large grains due to abnormal grain growth or recrystallization is an important process in oxide-dispersion-strengthened (ODS) alloys.The processing of steel is enabled with powder metallurgy, which utilizes powders consisting of a Fe-Al metal matrix with a large O content, prepared with mechanical alloying, and their hot consolidation due to rolling.The thermomechanical characteristics of new ODS alloys with a Fe-Al matrix are investigated in terms of the changes in the grain-size distribution.The recrystallization and grain growth were quantified after heating up to 1200 °C, which is the typical consolidation temperature for standard nanostructured ferritic steels.The results show that new ODS alloys are significantly affected by the thermomechanical treatment leading to microstructural changes.Recrystallization is mostly affected by decreasing the deformation and increasing the holding time, which leads to a growth of the grain size.