Studies of fracture processes in Cr–Mo–V ferritic steel with various types of microstructures

In this paper, the authors report on analysis of the influence of microstructure on ductile and cleavage fracture mechanisms. The question investigated was whether microstructure observations alone can provide sufficient information to predict the possible fracture mechanism or change in fracture mechanism. Four different microstructures of ferritic steel were tested after four different heat treatments. The microstructures examined were ferritic, ferritic–pearlitic, ferritic–bainitic, and tempered martensitic types. It was concluded that the ratio (SC/S0) of the area covered by carbides to the total area of a ferritic grain (measured by taking into account large carbides) is the only possible quantitative measure that can be used to predict cleavage fracture.