Study On The Microstructure Evolution And The High Temperature Oxidation Mechanism Of Twin-Roll Cast Fe-Cr-Al Alloy

Fe-Cr-Al alloys have been an ideal material for electric heating alloy with high temperature oxidation resistance.To solve the pollution problems caused by vehicle exhaust,Fe-Cr-Al alloys now are more and more used for vehicle exhaust purifiers carrier to replace the ceramic carrier with low catalytic efficiency.In order to ensure the high temperature oxidation resistance and good forming property,Fe-Cr-Al alloy is generally a thin strip of 30-100 ?m.The traditional method of producing Fe-Cr-Al alloy is complex and consumes large energy.The twin-roll strip casting can eliminating the continuous casting and hot rolling processes in the traditional technology for producing Fe-Cr-Al alloys,it is a new advanced and energy-efficient technology.The microstructure,mechanical properties and high temperature oxidation resistance of Fe-Cr-Al alloy produced by the twin-roll strip casting was investigated in this work to provide basis for the development and application of twin-roll strip casting Fe-Cr-Al alloy.The main work is as follows.(1)The strip quality were analysed.The micrographs and EPMA results about the cast strips show that there are many deficiency of the cast strips such as cracks,pores and slags.The slags are the oxide of aluminum and rare earth element.The slags cannot be eliminated during hot rolling,cold rolling and annealing.(2)The microstructure and mechanical properties of Fe-Cr-Al alloy after annealing were investigated by room-temperature tensile test.The annealing at 800? can cause recrystallization in a short time and the good mechanical properties were obtained.At the same annealing process,the heating temperature of 1050 ? or 1150 ?,has little effect on the mechanical properties.(3)The high temperature oxidation resistance of Fe-Cr-AI alloy was carried out with high temperature oxidation test.The results show that the oxidation kinetics curves of Fe-Cr-Al alloy at 1000? are the typical parabolic.X-ray Diffraction(XRD)and Energy Dispersive X-ray(EDX)shows that the oxide film is composed of Cr2O3 and Al2O3,the oxide film of Al2O3 grows along the scratch direction and non-uniformity.The spalling behavior of oxide film appeared on the Fe-Cr-Al alloy oxide film surface after being oxidized 48h at 1000 ?.The adhesion between the oxide scale and substrate is bad.The adding small amounts of Y and La can suppress the grain growth of Fe-Cr-Al alloys at high temperature.