Modelling the geometry constraints on the cleavage fracture toughness in ferritic steelsPages 137-147
D. Hariharan Abstract:
Assessing the possibility of cleavage fracture at given operating conditions is significant for the design and maintenance of critical engineering components in the energy, infrastructure and manufacturing sectors. Ductile to brittle transition describes the perceptible shift in fracture mode that occurs when temperature decreases, from slow ductile crack formation to quick cleavage. At very low temperatures, it has been demonstrated that local approaches to cleavage fracture developed based on weibull stress as a cleavage crack-driving force, may predict fracture toughness. But capturing the absolute effects of geometry remains a challenge. This article prescribes a new weibull stress formulation model with thinning function, which alters the number of cleavage-initiating features with temperature. It is found that the modified weibull stress is independent of the weibull shape parameter within the investigational error and it might predict the fracture toughness at any specified geometry and temperature without relying upon the empirical fits. The results prove that there is an excellent agreement observable between the experimental and the theoretical characteristic fracture toughness predicted by the modified Beremin model, rather than original Beremin model for the geometry condition of a/W=0.2 & 0.5 with a single shape parameter at -110°C.
Keywords: Cleavage fracture toughness,
Local approach to cleavage fracture,
Beremin model, Weibull stress,
Plastic strains,
Geometry effects
|
PDF 