Corrosion grain boundary

Baeumel, A. and Tramposch, O, Investigation of Intercrystalline Grain Boundary Corrosion of Austenitic Manganese-chromium Steels by Water and Aqueous Salt Solutions , Werkst. Korros., 17, 110 (1966) C.A., 64, 13847d... 

Lewis, E. C., Grain Boundary Corrosion of Sensitised Type 304 Stainless Steel by a Noble-to-active Polarisation Scan , J. Electrochem. Soc., 119, 219C (1972)... 

Potentiostatic methods, being capable of detecting differences in corrosion and passivation behaviour of various parts of a heterogeneous surface, have been applied to the electrochemical determination of grain boundary corrosion... 

Acids (HCl, H2S04, HN03...) Main attack at grain boundaries corrosion resistance can be improved significantly by tailoring the composition [18e, 506-518]... 

Diffusion of oxygen in oxidation scales occurs along grain boundaries. Corrosion of metals is controlled by formation and diffusion of point defects in the ceramic. Corrosion of polycrystalline ceramics also occurs most quickly along grain boundaries. 

To diminish the effects of hydrodynamic grain-boundary corrosion in applications with hot water, such as chipping out of fine grains in hot spots, tribochemical reaction with water... 

Devillers, J. P., and Niessen, P. (1976b). Accelerated grain boundary corrosion of dilute-aluminum alloys under high applied cathodic currents. Corrosion, 32(4). 152-154. 

Kehrer, H. P. (1974). The effect of small impurities on grain boundary corrosion of zinc die castings. Metall, 28(9), 883-889 (in German). 

The various forms of corrosion can be classified by their various causes. These are uniform corrosion attack (UC), bimetallic corrosion (BC), crevice corrosion (CC), pitting corrosion (PC), grain boundary corrosion (GBC), layer corrosion (LC), stress corrosion cracking (SCC), cavitation corrosion (CC), and hydrogen embrittlement (HE). 

Figure 4.26 SEM micrograph of grain boundary corrosion in HAZ of 316L SS Weldment (x900)...

Sensitization When austenitic steels, such as AlSl Type 304 are cooled slowly through the range 550-580°C, they are frequently susceptible to severe intergranular attack when exposed to a corrosive environment. This phenomenon has been termed sensitization which means the metal is sensitive to grain boundary corrosion. 

Also, indirect insight into the chemistry of the grain boundaries can be obtained by referring to early work by Westbrook (1967), in which electrochemical potentials and the grain-boundary corrosion properties are affected. These results could be explained by direct observation of the chemical compositions at the grainboundary plane. Thereby, the controlling element would be identiHed and also the correlation between these chemical properties and the chemistry at the grain boundary would be understood. 

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