Some Notes on the Oxidation Resistance Of Boron-Containing Chromium-Nickel-Cobalt-Iron Alloys

Abstract

Abstract During an investigation of a series of cast chromium-nickel-cobalt-iron alloys, it became of interest to gain some indication of the effect of boron on the oxidation resistance of this family of alloys. A series of alloys containing 18 and 20'percent chromium with various balances between nickel, cobalt, iron and boron were subjected to oxidation tests in air at 1650, 1830 and 2012 degrees F. Temperatures somewhat above those encountered in gas turbine applications were chosen to accelerate the attack since the effect of boron was not readily noticeable at temperatures below 1650 degrees F. Results of this investigation indicate that iron and boron and, to a lesser extent, cobalt have an adverse effect on the oxidation resistance. Molybdenum strongly decreases the alloys' resistance to oxidation. X-ray diffraction work indicated that protective Cr2O3 scales are not compatible with high boron contents, if the balance of the base alloy elements is not controlled. Boron was found to promote the form...