Selection of Materials for Parts Operating Under Bearing Contact and Erosion-Corrosion Wear Conditions

The effects of the simulataneous actions of erosion and friction on the wear of 4 kinds of cast-iron containing Cr 12.40-14.05 and C 1.15-1.71 wt percent were studied. Two of these cast irons were inoculated. The friction deformation of some of the cast irons had a large accelerating effect on the corrosion resistance. For instance, the corrosion rate of 2 cast irons during friction in a condensate medium without preliminary friction deformation, was 0. 0336 and 0.0292 mm/year, resp., while after deformation, the corrosion rate at similar conditions 0.056 and 0.0196 mm/year, resp. This difference is assumed to be the result of considerable changes in the structure of the surface layer. During friction deformation as the result of increased temp., phase and allotropic transformations took place to the depth of 45-60 mu, with the formation of austenite. Although austenite is more corrosion resistant than ferrite, vol. changes during the transformation resulted in the formation of fissures with resulting acceleration of corrosion disintegration. Cr, Mo, and W diffuse inward from the surface layer during the friction deformation and this also accelerates the erosion rate. For proper evaluation of the wear, the materials should be tested by exposure. (Author) Edited machine trans. of mono. Litye Iznosostoikie Materialy (Casting Wear-Resistance of Material), Kiev, 1969 p17-24, by Robert A. Potts.