Effect of Copper on the Corrosion Resistance Behaviour of As-Cast and Destabilized Cr-Mn White Cast Irons

Abstract

The effect of the addition of copper to Cr-Mn white cast irons in the as-cast and destabilized conditions and their performance in the chloride corrosive media were studied. This research was part of the development programme to consider substitute alloys for the existing costly wear resistant alloys like Ni-Cr or High Cr white cast irons for wear resistant applications. In the as-cast condition, a predominantly austenitic matrix was developed by the addition of Mn(∼5%) and Cu(∼3%) to the base iron with 2.8%C, 1.7%Si, and 6%Cr. These metastable austenitic alloys were subjected to destabilization ausaging treatment. The corresponding transformation behavior was characterized by optical microscopy, hardness measurement, x-ray diffraction analysis, and electron probe micro-analysis etc. The corrosion rate in 5% NaCl aqueous solution were measured by potentiostatic method and the corroded surfaces were examined under a scanning electron microscope with EDX facility. The observations prove the beneficial effect of copper on increasing the corrosion resistance of Cr-Mn white cast irons.