SEM and EBSD investigations of high-chromium cast irons

High-chromium white cast irons are alloys that are based on the iron-chromium-carbon system and are classified in ISO 21988-2006 as abrasion-resistant cast irons that contain greater than 11% chromium. High-chromium white irons are primarily used as castings and hard-facing weld deposits in equipment requiring resistance to abrasive and erosive wear under moderate impact loading conditions. These materials are used in the mining and chemical processing plants in applications such as grinding mills, slurry pumps, chute liners and pipes. The microstructures of high-chromium white irons contain a substantial proportion of chromium rich carbides that are harder than silica sand, which is a commonly encountered wear medium in mineral processing plants. High-chromium white irons are generally heat treated to develop maximum hardness via the precipitation of secondary carbides in the ferrous matrix during ageing at elevated temperatures and destabilisation of austenite, which subsequently transforms to martensite on cooling to room temperature.