An SEM study of the tensile fracture of metallurgical coke

Abstract

An SEM study of the tensile fracture of an experimental blast-furnace coke is described, the objective being to further the understanding of the failure of coke under diametral compressive loading and the influence thereupon of the textural components of the coke carbon. The approach adopted was to examine etched surfaces of the central spherical plane of cylindrical test specimens after loading diametrically. For each specimen, a diagram was drawn indicating the number, size and position of the flaws present, a note being made of the textural component through which the flaw passed. It was found that textural components were present at flaws in the same proportions as in the coke as a whole, implying that the initiation and propagation of microcracks is not influenced by any variation in the properties of the coke textural components. Fracture resulted when microcracks, initiated at pores in the coke at lower stress levels, joined together to form a flaw of critical size. Fracture crack systems were very complex, but nevertheless always contained a diametral fracture, this being indicative of a valid test.