Brittle FractureDOE-HDBK-1017/2-93BRITTLE FRACTURE MECHANISMBRITTLE FRACTURE MECHANISMPersonnel need to understand brittle fracture. This type of fracture occurs underspecific conditions without warning and can cause major damage to plantmaterials.EO 1.1DEFINE the following terms:a.Ductile fracturec.Nil-ductility Transition b.Brittle fracture(NDT) TemperatureEO 1.2DESCRIBE the two changes made to reactor pressure vessels todecrease NDT.EO 1.3STATE the effect grain size and irradiation have on a material'sNDT.EO 1.4LIST the three conditions necessary for brittle fracture to occur.EO 1.5STATE the three conditions that tend to mitigate crack initiation.EO 1.6LIST the five factors that determine the fracture toughness of amaterial.EO 1.7Given a stress-temperature diagram, IDENTIFY the followingpoints:a.NDT (with no flaw)c. Fracture transition elastic pointb.NDT (with flaw)d. Fracture transition plastic pointBrittleFractureMechanismMetals can fail by ductile or brittle fracture. Metals that can sustain substantial plastic strain ordeformation before fracturing exhibit ductile fracture. Usually a large part of the plastic flow isconcentrated near the fracture faces. Metals that fracture with a relatively small or negligible amount of plastic strain exhibit brittlefracture. Cracks propagate rapidly. Brittle failure results from cleavage(splitting along definiteplanes). Ductile fracture is better than brittle fracture, because ductile fracture occurs over aperiod of time, where as brittle fracture is fast, and can occur (with flaws) at lower stress levelsthan a ductile fracture. Figure 1 shows the basic types of fracture.Rev. 0Page 1MS-04
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business