Advances in the mechanism of cleavage fracture of low alloy steel at low temperature. Part III: Local fracture stress σ

Local fracture stress values σ were measured accurately using 4PB, COD and Charpy V specimens. σ is the most stable parameter characterizing the fracture toughness of materials. It's scattering is analyzed to be determined only by the size distribution of the largest particles, accounting for less than 5 percent of the total particles of the weakest constituent, and is not subject to the influence of their locations. The toughness of a structurally heterogeneous zone such as a weldment could be characterized by a unique value of σ or σ/σy with a narrow band of scattering. σ or σ/σy is a potential engineering parameter used for assessment of fracture toughness of materials. The physical meaning of σ associated with the surface energy is discussed in detail