IMPROVING THE HIGH-TEMPERATURE PROPERTIES OF A NEW GENERATION OF Fe-Al-O OXIDE-PRECIPITATION-HARDENED STEELS

Increasing efficiency in power engineering is conditional on the improvement of the high-temperature properties of structural materials. A new Fe-Al-O Oxide-Precipitation-Hardened (OPH) steel was developed by the authors to dissolve the required amount of O in the matrix during mechanical alloying and let a fine dispersion of Al oxides precipitate during the hot consolidation. Compared to oxide-dispersion-strengthened (ODS) ferritic steels, excellent oxidation resistance is guaranteed by using 10 % Al in the matrix. To improve the high-temperature properties of OPH, a series of thermomechanical tests was performed to investigate the recrystallization and grain growth of the microstructures by metallographic analysis. The results show that the heat treatment has a significant influence on the mechanical properties of OPH as well as the microstructure and recrystallization of the grains. It decreased the UTS to almost 25 % of the initial state, while causing plastic deformation. Also, grain growth was observed up to 16 %, even with no annealing and applied deformation, which shows a good structure-oriented material.