Abstract:

Microstructure and precipitates of the FeCrAl stainless steel before and after extrusion were investigated, the microstructure, precipitates, recrystallization and mechanical properties of it after annealing process were also investigated by using optical microscope (OM), scanning electron microscope (SEM), electron backscattered diffraction (EBSD) and universal tensile testing machine. The results show that the Nb content has a significant impact on the precipitation of secondary phases, especially, the precipitation temperature and amount of the Laves phase both increases under the high Nb content. Decreasing the extrusion temperature has contributed to the formation of fine dispersed second phases of FeCrAl stainless steel cladding pipes. With the increase of annealing temperature, the precipitation quantity of fine dispersed phases increases first and then decreases. Under the same annealing process, the room temperature mechanical properties of 800 ℃ extruded tubes are better than those of 950 ℃ extruded tubes.

Key words: FeCrAl alloy, Laves phase, mechanical properties