The role of microstructure in brittle fracture behaviour of low alloy tempered bainitic steel

The validity of various micromechanistic models for the cleavage initiation in tempered bainite have been tested using two quite different model bainitic microstructures. The microscopic cleavage fracture stress (CFS) was measured for both microstructures using Charpy V-notch type specimens. Various micromechanistic models were applied to experimental results to explain the metallurgical nature of CFS. The validity and applicability of these models for a particular bainitic microstructure have been discussed.