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 Posted: Thu 1:50, 30 Dec 2010 Post subject: ed hardy Improved exfoliation corrosion resistance |
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Alloy to improve the LC15 of exfoliation corrosion resistance
Solution) caused. Since grain boundaries are all kinds of dislocations, impurities, and plot the location of precipitation together, so the higher energy, is the corrosion of sensitive parts of the passive film on metal surfaces is relatively weak in these locations. In corrosive media, especially the chloride medium, where the first corrosion, resulting in corrosion pits. When the corrosion depth within the metal, after the 62 ounces of light metal in 1997 the Ministry of occluded Nil9 further deterioration of the corrosion environment (pH decreased, cl a concentration), corrosion will be further developed to the depths of the J. If the pit equiaxed grains along the depth direction to the thickness of the expansion, that is, between the formation of corrosion products. If the pits are elongated along the grain into thin strips parallel to the horizontal expansion of the metal surface, namely the formation of exfoliation corrosion. The transgranular type of exfoliation corrosion, there is no uniform understanding of the present, it was considered by the T-phase due to the residual tissue, it was considered by the Fe or (Mn + Fe) precipitates and deformation in the crystalline form of bars under the effect of institutions like distribution caused. More common view is: that the exfoliation corrosion mainly Mn, Cr, Ti and other transition elements related. In the crystallization process, the total product-based elements such as Mn enrichment at the grain boundary and the boundary branch products, including elements such as crystal, Ti enrichment in the grains, the deformation and heat treatment, the distribution of the formation of lamellar alternating shades, which prone to exfoliation corrosion. In this experiment, without directly CGS1 uniform treatment of l samples, metallographic examination showed: Mn was precipitated particles distribution strip or band of fibrous tissue, so that alternate between rich and poor distribution of elements of the transition journey. In corrosive media, because of the rich layer faster than the poor passivation layer, from the cathode effect, so the corrosion preferentially depleted layer,[link widoczny dla zalogowanych], rich layer were retained to form a typical layered corrosion. 2 by the 24h sample homogenization, recrystallization large degree, there subgrain band, Mn particle aggregation, reduce the potential difference between rich and poor layers, and thus reduce the degree of exfoliation corrosion. The high temperature for a long time (48h) 3 sample homogenization, rich and poor elimination of fibrous tissue, tissue is more homogeneous; vertical and horizontal consistency to the mechanical properties (see Figure 1), from mechanics to fully confirm the homogeneity of the organization, which exfoliation corrosion has also been improved. Observe the situation from the scene, there is still at the scene of contact corrosion. The site where iron bolts,[link widoczny dla zalogowanych], corrosion serious than other locations, because the cathode of aluminum and iron that were dissimilar metal connections, the larger the potential difference between the two asked, leaving the heavier exfoliation corrosion. Therefore, in equipment assembly, attention should be painted on the cover bolts to cut off the source of the corrosion of alloys. Currently, most researchers believe that domestic and foreign, exfoliation corrosion and corrosion on aluminum alloy to ask, but the U.S. laboratory that Alcoa, the grain can cause internal corrosion program off the corrosion J, Goard also mentioned in the intergranular corrosion is not sensitive exfoliation corrosion of aluminum found in J. However, no matter what kind of views held, scholars have recognized the exfoliation corrosion initiation of passive film breakdown from the start, and with the closely related pitting breakdown potential. In this study, did not find LC15 loss meal together Jinyou Jing Q sensitivity, so the corrosion mechanism of the peeling remains to be further explored four field experiments to three samples after homogenization into Xieqiao, its waste rock is fixed in the two wells on the cage, field corrosion for three months,[link widoczny dla zalogowanych], the results of laboratory results consistent with the conclusion aLC15 5 alloy after two-step aging, intergranular corrosion are zero. b. LC15 Taijin by 465 �� / 48h (air furnace) +470 �� �� 50C/60min (Salt words furnace) + l0O �� / 8h + l65 �� / 16h after treatment, exfoliation corrosion can be improved. c. Actual installation in the field, avoid direct contact between dissimilar metals, corrosion of the alloy to cut off the source. 6 References 1ShafferISe ��alJMaleriais, 1968,3 (2): 4002GB7998-82 aluminum corrosion test Taijin Crystal asked 3ASrMG34-79StandardTatMethodofEX-F0LIATI () NCORR0SIoNSVSCEPTIBILITYIN2AND7SERIESALUMINIUMALLoYS (EXCOTEST) 4 left Hisashi, Lee received material protection. Erosion of domestic and international status of aluminum Taijin 1994, �� 12,23 ~ 265 Li Jiuqing other materials protection, marine corrosion mechanism of aluminum-magnesium alloy flake of 1994,[link widoczny dla zalogowanych], �� 4.1 ~ 66Spmr/sDoeta1. ASTMSTP,[link widoczny dla zalogowanych], l9 him. 516:387 ShafterISASTMSTP. 1972.516:3 Received Date :1997-05-06 juvenile shrews valve control device
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