Specific Features of the Fracture of High-Chromium Cast Irons Under Abrasive Wear

It is shown that the fracture of high-chromium cast irons in dry and wet abrasive media depends on their chemical composition, structures, distribution of chromium in the metal base, properties of the abrasive and strongly depends on the Rehbinder effect and the formation of microgalvanic couples. It is established that the procedure of annealing increases the chemical inhomogeneity of the distribution of chromium in the metal base. The presence of zones near carbides with low chromium contents not higher than 8.5% (negative potential) and the central parts of grains with chromium concentrations higher than 12% (positive potential) leads to the formation of microgalvanic couples in electrolytic media. It is shown that the fracture process is intensified in the presence of particles with sizes of up to 0.5 μm (pulp) accelerating this process and increasing mass losses in the abrasive medium. We propose grades of cast irons for the cast components with regard for the operating conditions.