Microstructure And Erosion-Corrosion Behaviour Of As-Cast High Chromium White Irons Containing Molybdenum In Aqueous Sulfuric-Acid Slurry

Abstract

Microstructure and erosion-corrosion behaviour of as-cast high chromium white irons containing molybdenum in aqueous sulfuric-acid slurry was studied. The experimental irons contained 28 wt.%Cr with a Cr:C ratio of about 10 and up to 10 wt.%Mo. The irons with up to 6 wt.%Mo are hypoeutectic, whereas the iron with 10 wt.%Mo becomes eutectic/peritectic. Mo addition promotes formation of M[23]C[6] and M[6]C, instead of typical M[7]C[3]. Erosion-corrosion testing was performed in aqueous sulfuric-acid slurry containing alumina particles. The hypoeutectic Fe-28Cr-2.7C-1Mo with mainly M[7]C[3] and the eutectic/peritectic Fe-28Cr-2.6C-10Mo showed reduced wear rates of about 30% and 7% of that of the reference iron without Mo addition, respectively. The reduction of the carbide-matrix hardness difference, the increase of corrosion resistance of the matrices, and the increase of macro-hardness are determining factors for the improvement of erosion-corrosion resistance of the irons.