Brittle failure
with brittle failure (also separation break), is designated a suddenly arising material failure. It arises particularly with hard and brittle materials with small ductility and tenacity, a typical example: Glass, ceramic(s), ice. Brittle failures take place with smaller or without plastic deformation. There most metals duktil break find one this form of the break only with some metals and only on certain demand conditions. To the brittle failure math <\> alpha /math< bend> - iron, chrome, molybdenum, tungsten, beryllium and zinc, brittle failures can however also with duktilen metals occur, approximately at very low temperatures, with large cross sections of the material or with very high deformation rates (impact effect, explosion).
Brittle materials draw effected in the stress-strain curve via for steep rise of the Hook straight lines out at their end the break. The beginning of break takes place via small errors, at which tensions concentrate. The tear can spread with speed of sound in the metal and arises usually by splitting to on certain kristallografischen levels (frequently on {the 100} - level), one speaks of a transcrystalline fracture course. Brittle failures with intergranular process less often arise, these are to be observed if at the grain boundaries relatively large quantities of eliminations or inclusions are.
The brittle failure shows itself on the basis the surface of fracture, due to typical characteristics. With a transcrystalline fracture course, the surface of fracture a crystalline appearance has, since the grains are split up into different levels with different orientations (the appearance resembles that of the Kandiszuckers). A further frequently occurring characteristic is that so-called. Chevronmuster. It has several break situations, which lie in different heights of the material. The surface shows a fan-like sample, beginning at the tear origin outward running, with deep furrows and burrs. The Chevronmuster, recognizably with the naked eye or a magnifying glass, is always an indication for the brittle failure and lets an impact as a tear cause assume. The occurrence of the brittle failure is thus no exclusive indication for Herstellungsfehler or inferior manufacture quality.
other kinds of break
deformation break, fatigue fracture (also fatigue failure gemannt), mixed fracture
