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mild steel cracks in the presence of alkali (e.g. boiler cracking and caustic stress corrosion cracking) and nitrates; copper alloys crack in ammoniacal solutions (season cracking); high-tensile steels have been known to crack in an unexpectedly brittle manner in a whole variety of aqueous environments, especially when chlorides are present.
Fractography can determine whether a cause of train derailment was a faulty rail, or if a wing of a plane had fatigue cracks before a crash. Fractography is used also in materials research, since fracture properties can correlate with other properties and with structure of materials.
Fracture mechanics is the field of mechanics concerned with the study of the propagation of cracks in materials. It uses methods of analytical solid mechanics to calculate the driving force on a crack and those of experimental solid mechanics to characterize the material's resistance to fracture.
The brittle fracture theory of Stoloff and Johnson, [14] Westwood and Kamdar [15] proposed that the adsorption of the liquid metal atoms at the crack tip weakens inter-atomic bonds and propagates the crack. Gordon [16] postulated a model based on diffusion-penetration of liquid metal atoms to nucleate cracks which, under stress, grow to cause ...
Fracture ductility tends to decrease, with the magnitude depending on the presence of small cracks to begin with. To perform these tests, an electro-hydraulic servo-controlled testing machine was generally used, as it is capable of not changing the stress amplitude. It was also discovered that performing low-cycle fatigue tests on specimens ...
Season cracking is characterised by deep brittle cracks which penetrate into affected components. If the cracks reach a critical size, the component can suddenly fracture, sometimes with disastrous results. However, if the concentration of ammonia is very high, then attack is much more severe, and attack over all exposed surfaces occurs.
Unexpected signs of inflammation Inflammation is your body’s way of kicking into overdrive to solve a problem, like an infection or injury. But your body parts aren’t designed to withstand ...
The size of a striation for a particular material is typically related to the magnitude of the loading characterised by stress intensity factor range, the mean stress and the environment. The width of a striation is indicative of the overall crack growth rate but can be locally faster or slower on the fracture surface.