WEAR AND OXIDATION BEHAVIOUR OF SOME CHROMIUM AND CHROMIUM-NICKEL STEELS IN CEMENT INDUSTRY

Abstract

The abrasive wear resistance and cyclic oxidation properties of some chromium -nickel and chromium alloys that are commonly used as a cooler lining and ball mill lining and diaphragm material in cement industry were investigated. Room temperature microstructure were examined using optical metallographic techniques which shows that the Cr-Ni alloys posses an austenitic structure with some carbides and Cr alloys posses feni.te + carbide or martensitic structure depending on the carbon and Cr level in alloys. Mechanical properties of these alloys at room temperature and 300, 700, 800 and 100C were tested and tabulated. Wear tests were conducted at three different loads which were 600, 1000 and 1500 grams and at different sliding rates of 20, 28 and 35 cm/sec. Each test was carniec out at a constant sliding distance of 300 meters. The 5.5% Cr alloy along w.th the used alloy# 6 posses a very poor wear resistance as compared with other alloys but as the load increases their wear rate decreases compared with other alloys. However, increasing the sliding rate causes a very sharp in the wear resistance of these two alloys compared with the othzr alloys. Increasing the Cr equivalent up to 22 improves wear resistance of these alloys but further increase in Cr equivalent did not give any wear improvement. Cyclic oxidation of these alloys were conducted at four different temperatures which were 800, 900, 1000 and 1100°C for total oxidation time of 48 hrs. under ambient conditions.