Ductile/brittle Fracture Ductile materials are materials which displays large numbers of plastic deformation, while brittle materials show little or no plastic deformation before fracture. The diagram is the a tensile stress-strain curve, which represents the degree of plastic deformation exhibited by both brittle and ductile materials before fracture. Crack initiation and propagation are vital to fracture. The manner in which the crack propagates through the material gives great insight into the mode of fracture. In ductile material ( ductile fracture), the crack moves slowly and is assisted by large amount of plastic deformation. The crack does not usually extend unless when an increased stress is applied to it. But on the other hand, when …show more content…
A primary use of the Charpy and Izod tests is determining if a material experiences brittle to ductile transition with a decreasing temperature. Brittle to ductile transition is directly related to the temperature dependency of the impact energy absorbed. An examination of the failure surface can prove very beneficial. When a section of the failure surface seems to demonstrate appears to demonstrate the visual properties of both the brittle and ductile fracture, then the brittle to ductile transition is evident at that temperature range. It is really important to remember that with most specimens, there is a fairly wide band of temperatures which support brittle to ductile transition. Therefore, for many specimens it is almost impossible to predict any one temperature as the transition …show more content…
First and foremost, brittle fracture occurs for quickly and catastrophically without any warning. Ductile materials plastically deforms, thereby slowing down the process of the fracture and giving ample time for the problem to be corrected. Secondly because of plastic deformation, more strain energy is required to cause ductile fracture. Next, ductile materials are considered to be forgiving materials because of its toughness, you can make a mistake in the use, design of a ductile material can be increased through the use of one of the strengthening mechanisms. For example strain hardening, as the ductile material is deformed more and more its strength and its hardness increases because of the generation of more and more dislocations, so, in engineering applications, especially the ones which have safety concerns involved, ductile materials are the obvious choice. Safety and dependability are the main concern in a material design, but in order to attain these goals, there needs to be a thorough understanding of the fracture both brittle and ductile. Understanding fracture and failure of materials will lead the materials engineer to develop a safer and more dependable materials and