FRACTURE OF A LOW CARBON TEMPERED MARTENSITE

Abstract

On the analogy of the ferritic steel, the effective grain is defined as a region in which cleavage crack runs nearly straight. It is shown that the microstructure %corresponding to the effective ferrit grain is the 'co-variant packet' extending thro%ughout a bundle of the martensite. The reason why the structure consisting of fine martensite fractures with a large cleavage facet was found to be due to the #fractures with a large cleavage facet was found to be due to the fact that most of martensite plates or laths in a packet have the same crystallographic orientation and the cleavage plane is quasi-continuous throughout the packet.