ABSTRACT
The metallurgical mechanisms of brittleness in steel are complex and do not come under the purview of this text. However, for the purpose of the structural designer, it would be useful to understand that brittleness is characterized by a fracture that propagates rapidly at a relatively low tensile stress, and at low temperature, and is often associated with little or no prior plastic deformation. Propagation of such crack requires much less energy compared to a ductile crack, which is preceded by a considerable plastic deformation until the load exceeds the value corresponding to its yield stress. Thus, brittle fracture may occur at an applied load much lower than at which failure would normally be expected and usually starts from areas of high local stress concentration, such as welding crack and notch.
