This paper presents the results of an experimental and numerical study carried out to investigate the effect of warm pre-stressing on cleavage fracture in ferritic steels using cracked and notched specimens. The local approach based on Weibull assumptions is used to quantify this effect. It is shown that the local approach predicts the increase in toughness following warm pre-stressing in highly constrained geometries. The observed effect of pre-loading in low constraint specimens such as round notched bars is less. The local approach could not predict the differences. It is suggested that the variation of triaxiality factor, which is the ratio of hydrostatic stress to Von Mises, in the plastic zone, was a contributing factor.

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