Microstructure and high temperature mechanical properties of as-cast FeCrAl alloys

The microstructure and high temperature mechanical properties of as-cast FeCrAl alloys with varying aluminum contents were experimentally investigated. Crystal phases were identified using X-ray diffractometry and the solidified structures were analyzed, taking into account the freezing range, AlN precipitation and the aluminum addition. A series of tensile tests were conducted at temperatures from 700 °C to 1200 °C and the effects of aluminum content on the stress-strain behavior including peak stress, yield stress and Young's modulus were investigated. The solid-solution strengthening of aluminum is reflected by the increase of peak stress and yield stress with increasing aluminum content at all temperatures, particularly below 1000 °C. Hot ductility is discussed in terms of the variations of the reduction in area value with temperature. Decreased ductility between 800 °C and 900 °C is attributed to ferritic grain coarsening and the precipitation of carbides within the grain boundaries. The occurrence of continuous dynamic recrystallization under the conditions of this study, can play an important role in grain refinement thus increasing the hot ductility of FeCrAl alloys.