What is transgranular and intergranular?
What is transgranular and intergranular?
While intergranular cracking denotes the failure of interfaces between contiguous grains, transgranular cracking refers to the failure of individual bulk grains along specific crystallographic planes.
What causes intergranular attack?
An intergranular attack is caused by the segregation of impurities at the grain boundaries or by enrichment or depletion of one of the alloying elements in the grain boundary areas.
What happens in intergranular corrosion?
Intergranular corrosion (IGC) is a form of localized corrosion characterized by preferential corrosion at grain boundaries or areas adjacent to them, with little or negligible attack on the grains. Similarly to other forms of localized corrosion, it mainly occurs on passive alloys exposed to specific corrodents.
Is brittle fracture intergranular or transgranular?
Intergranular brittle fracture involves cases in which the grain surfaces do not have dimples that signify microvoid coalescence. Such fracture is termed brittle due to fracture prior to plastic yielding.
What is intergranular crack propagation?
Intergranular fracture is the propagation of cracks along the grain boundaries of a metal or alloy. It is a fracture that follows the grains of the material. Intergranular fractures travel along the grain boundaries, rather than through the actual grains.
Where does intergranular corrosion occur?
the grain boundaries
Intergranular corrosion is localized attack along the grain boundaries, or immediately adjacent to grain boundaries, while the bulk of the grains remain largely unaffected.
What is transgranular corrosion?
Transgranular corrosion is a type of localized corrosion which occurs along cracks or faults across the crystals in metals and alloys. It follows the pattern of grains in the individual lattices of the material. Stress corrosion of austenitic steels is usually transgranular.
What is intergranular corrosion explain with an example?
Corrosionpedia Explains Intergranular Corrosion (IGC) Stainless steels and weld decay sensitization are the best examples of intergranular corrosion. Grain boundaries that are rich in chromium elements will precipitate lead. This makes the boundaries very vulnerable to corrosion attacks in various electrolytes.
What is transgranular brittle fracture?
A transgranular fracture is a fracture that follows the pattern of grains in the individual lattices of the material. This is one type of brittle fracture. Transgranular fractures are also known as transcrystalline fractures.
What is intergranular brittle fracture?
An intergranular fracture is one kind of brittle fracture. When brittle fracture occurs, the crack initiates and propagates through the material at high speeds (the speed of sound). Factors that favor crack initiation include: Larger grain size. Lower temperatures.
How much al is in the glassy phase of intergranular glass?
Al element of 1 at% was detected in the fracture surface but very little (<0.1 at%) in the grinding surface. These analyses suggests that Al impurity of the order of several hundred ppm was nearly localized in the grain boundary, and that it promotes to reduce viscosity of the intergranular glassy phase.
Can intergranular F phase precipitation mitigate alloy 725 he risks?
The deleterious effect of intergranular F phase precipitation could be used to develop feasible approaches to detect susceptible microstructures and, thus, mitigate Alloy 725 HE risks. Firstly, it is strongly advisable to increase the impact toughness requirement suggested by the API 6ACRA standard 1.
What is the difference between intergranular and transgranular cracking?
While transgranular cracking is favored by strain localization (which in turn is encouraged by smaller grain sizes), intergranular fracture is promoted by strain homogenization resulting from coarse grains. Embrittlement, or loss of ductility, is often accompanied by a change in fracture mode from transgranular to intergranular fracture.
Does intergranular crack propagation release more energy than Griffith theory?
From an energy standpoint, the energy released by intergranular crack propagation is higher than that predicted by Griffith theory, implying that the additional energy term to propagate a crack comes from a grain-boundary mechanism. Intergranular fracture can be categorized into the following: