Characterizing Brittle-Fracture Resistance of Steel

Abstract

The description of fracture resistance of steel in the ductile/ brittle transition region is treated as a multi-parameter problem. Some metallurgical factors influencing two of the parameters (lower- shelf toughness and sharpness of the transition) are discussed. For a series of HSLA steels which are variants on ASTM A710A, removal of Cu increased the lower-shelf toughness and tended to sharpen the transition. Ni removal also tended to sharpen the transition, while C and Nb additions tended to smooth it.

The two other parameters describing toughness reflect uncertainty and can lead to severe data scatter: uncertainty in translating the transition temperature derived from impact energy into an equation relating fracture toughness to temperature and scatter in fracture toughness itself apparantly arising from microstructural non-uniformity. Some implications of these findings with regard to materials characterization are discussed.