Fracture toughness of 5 Cr-Mo-V high-strength sheet steel

Abstract

The critical fracture toughness parameter, K c , of H-11 sheet steel reflected a degree of independence of specimen thickness, in the instance of the intermediate yield strength level ( σ YS = 205 ksi), when considered in terms of any particular test temperature within the range −300 to 300°F. The K c parameter generally followed the trend established by increasing proportion of shear fracture, regardless of the existence of individual or collective effects of sheet thickness, tempering temperature or test temperature. Fracture appearance transition temperature, FATT, of H-11 steel was observed to increase, generally, with increasing sheet thickness for σ YS = 205 and 243 ksi. FATT was essentially independent of thickness for σ YS = 174 ksi. The effect of increasing sheet thickness was relatively more pronounced in elevating FATT than was the effect of decreasing tempering temperature.