qizhen0809
Legenda soseske
Pridružen/-a: 10.01. 2017, 10:56
Prispevkov: 621
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 Objavljeno: 31 Jan 2018 06:29 Naslov sporočila: slip steps |
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| <p>Dissolution theory: there is a local weak point on the oxide film on the surface of the aluminum alloy in which SCC occurs, and the dislocations inside the alloy matrix will move along the slip under the heirloom stair and railings action of stress to form a slip step. When the slip step is large, the surface film can not follow The formation of slip steps and the corresponding deformation occurs, the film will rupture and bare exposed surface, contact with the corrosive medium, rapid anodic dissolution. </p> <p> film rupture theory: corrosive medium metal surface protective film, due to stress Or the role of active ions caused by rupture, bare surface and the rest of the surface film constitutes a small anode large cathode corrosion cells, resulting in a new Anodic dissolution occurs on the surface Anodic fixing composite decking to concrete dissolution and hydrogen induced cracking together Anodic dissolution and hydrogen induced cracking are two different concepts, pure anodic dissolution can be prevented by cathodic protection, and for hydrogen induced cracking, cathodic polarization tends to be Promote cracking. Some systems mainly anode dissolution, while others are mainly caused by hydrogen-induced cracking.</p> <p> Aluminum alloy SCC often include both processes, to distinguish between these two phenomena is actually difficult. The results show that the SCC of 7050 aluminum alloy in 3% NaCl solution is the result of the combined effect of anodic dissolution and hydrogen-induced cracking.In the beginning, local anodic dissolution occurred due to the potential difference of the particles in the grain boundaries of the alloy, resulting in the rupture of the passivation film With the increase of local anodic dissolution in the graindeck stain grey boundary, the reducing H atom diffused into the process area and interacted with the microstructure, crack tip stress and plastic strain, causing damage.</p> |
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