AbstractBased on the three parameter Weibull distribution of the critical stress required for the cracked martensite–austenite (M–A) constituent to initiate cleavage, a statistical model has been derived of the transgranular cleavage fracture in granular bainite in weld heat affected zone. From the assumption that cleavage fracture is the result of the statistical competition between microcracks of various sizes in a stress field, a new definition of cleavage fracture stress is given by using the statistical model, further developed to take account of the particular stress distribution in a pure bend notched specimen of strain hardening material. The cleavage fracture load and cleavage fracture stress predicted using the model are in good agreement with the experimental results.MST/954