Corrosion metallurgical aspects

Osozawa, K., Metallurgical Aspects of Intergranular Corrosion of Stainless Steel , Boshoku Gijutsu, 22, 267 (1973) C.A., 80, 85981V... 

V. Cihal, Metallurgical Aspects of Knife-Line Attack on Stabilized Stainless Steels, Localized Corrosion NACE 3, R.W. Staehle, B.F. 

E. ViUalba, A. Atrens, Metallurgical aspects of rock bolt stress corrosion cracking. Mater. Sci. Eng. A 491A (2008) 8-18. 

Metallurgical aspects of alloyed steel. The alloying of the different modifications of iron with other metals leads to a shear infinite number of materials all with different corrosion properties. The alloying element stabilizes one or the other modification of steel. In a rough scheme one can distinguish the following main routes ... 

Grimsdottir, M.R., Gjerdet, N.R. and Hensten-Pettersen, A. (1992) Composition and in vitro corrosion of orthodontic appliances. Am. J. Orthod. Dentofac. Orthop., 101, 525-532 Discusses sensitivity and stainless steels. Release of nickel related to many metallurgical aspects and not necessarily to nickel content of the metal. 

Metallurgical aspects of nickel and the corrosion of nickel-containing materials in contact with sweat have been reviewed (Morgan and Flint 1989 Flint 1998), and some of the most relevant information is summarised below. 

The residual stress in a metal, or more commonly an alloy, wiU, in certain corrosive environments, result in mechanical failure by cracking. It first became apparent at the end of the nineteenth century in brass (but not copper) condenser tubing used in the electric power generating industry. It was then called season cracking. It is usually prevalent in cold-drawn or cold-roUed alloys which have residual stress. Heat treatments to relieve this stress were developed to solve the problem. It was soon realized that there were three important elements of the phenomenon the mechanical, electrochemical, and metallurgical aspects. 

Another metallurgical aspect to consider is the dislocation network encounter in plastically deformed alloys, hi general, dislocations are linear defect, which can act as high energy lines and consequently, they are susceptible to corrode as rapidly as grain boundaries in an corrosive medium. Figure 1.12 illustrates dislocation networks in an AISI 304 stainless steel and in RSA hfissMossBbFea. The relevant pretreatment conditions can be found elsewhere [19]. 

T. Magnin and J. Lepinoux, Metallurgical aspects of the brittle SCC in austenitic stainless steels, in Parkins Symposium on Fundamental Aspects of Stress-Corrosion Cracking (S. M. Bruemmer,... 

The phenomenology of localized corrosion helps to define certain requirements for localized corrosion that can be expressed in terms of the concepts already discussed in Chapter 2. In order for localized corrosion to occur, there must be a spatial variation in the electrochemical or metallurgical conditions. The occurrence of discrete sites of attack demonstrates that passivity must be able to coexist on the same surface with active regions. In fact, this is one of the scientifically interesting aspects of localized corrosion. Under normal circumstances, one would expect that a surface would either be completely passive or completely active, not a mixture of the two. Finally, there is a physical separation of the anodic and cathodic reaction sites during localized corrosion. In order to understand localized corrosion and thus how to test for resistance to localized corrosion, we must understand each of these aspects and their interrelations. 

Carbon steels. The corrosion behavior of carbon steel weldments produced by fusion welding can be due to metallurgical effects, such as preferential corrosion of the heat-affected zone (HAZ) or weld metal, or it can be associated with geometric aspects, such as stress concentration at the weld toe, or creation of crevices due to joint design. 

Stress corrosion is the failure of a metal resulting from the conjoint action of stress and chemical attack. It is a phenomenon associated with a combination of static tensile stress, environment and in some systems, a metallurgical condition which leads to component failure due to the initiation and propagation of a high aspect ratio crack. It is characterized by fine cracks which lead to failure of components are potentially the structure concerned. Stress corrosion cracking is abbreviated as see. The failures are more often sudden and unpredictable which may occur after as little as few months or years of previously satisfactory service. 

J.R. Weeks, H.R. Isaacs, A general model for the corrosion of steels in high velocity sodium, in S. A. Jansson (Ed.)> Proc. Symp. On Chemical Aspects of Corrosion and Mass Transfer in Liquid Sodium, Metallurgical Society, 1971, p. 207. 

From this brief review it appears that all these affecting parameters are not only metallurgical parameters and clearly demonstrate the need to develop or to apply local probes to reach an in-situ and a real time monitoring of Ae dimensional aspect of the localized corrosion (Fig. 4). On the other hand the Fig. 4 indicates that very close to the surface the solution chemistry changes can be significant so that the conductivity may be unknown (depends on supporting electrolyte concentration) and also some of the current is carried by diffusion. Thus, as indicated there will be limita-... 

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