ALUMINUM CONTAINING IRON-BASED ALLOYS, CHARACTERIZED AS ROOM TEMPERATURE DUCTILITY, RESISTANCE TO THERMAL OXIDATION, CYCLIC FATIGUE RESISTANCE, ELECTRICAL RESISTIVITY, LOW AND HIGH TEMPERATURE STRENGTH AND/OR HIGH TEMPERATURE SAG RESISTANCE, USEFUL AS ELECTRICAL RESISTANCE HEATING ELEMENTS

摘要

PURPOSE: To provide an aluminum-containing iron-based alloy useful as an electrical resistance heating element, wherein the alloy has improved room temperature ductility, resistance to thermal oxidation, cyclic fatigue resistance, electrical resistivity, low and high temperature strength and/or high temperature sag resistance, and the alloy preferably has low thermal diffusivity in addition. CONSTITUTION: The electrical resistance heating element is formed from an iron aluminide alloy comprising, by weight, 4 to 32% of Al, 1% or less of Cr and Zr in an amount effective to form zirconium oxide stringers extending perpendicular to an exposed surface of the heating element and pin surface oxide on the heating element during cycling between ambient and temperatures over 500 deg.C, wherein the alloy has a ferritic microstructure which is austenite-free.