Improvement of room temperature tensile properties for Fe3Al-based alloys by thermomechanical and annealing processes

The effects of thermomechanical and annealing processes on room temperature tensile properties of Fe3Al-based alloys have been investigated. It is found that the thermomechanical process affects the room temperature tensile properties of Fe3Al-based alloys greatly. It is very important to control the hot deformation process so that a fine grain microstructure can be obtained before the final warm-rolling process. A higher room temperature ductility combined with a higher yield stress can be obtained by refining grains of Fe3Al-based alloys and obtaining the B2 ordered structure with a suitable surface state, such as oil film, Al2O3 film and an aluminium-poor region near the surface. The intrinsic factors, such as microstructure and crystal structure, and extrinsic factors, such as surface condition, must be considered when the sensitivity to environmental embrittlement is investigated. An advanced thermomechanical process, named controlled thermomechanical process, to further improve room temperature tensile properties has been developed. It consists of hot forging an ingot to 20 mm at 1000–1200°C, hot rolling it to 10 mm at 850–1000°C, warm rolling to 5 mm thickness at 500–680°C, then annealing at 800°C for 1 h, then warm rolling to 2 mm thickness at 500–680°C.