And metallurgical influence

C. A. Siebert, D. V. Doane, and D. H. Breen, The Hardenability of Steels—Concepts, Metallurgical Influences andindustrialApplications, American Society for Metals, Metals Park, Ohio, 1977. 

A complete discussion of the corrosion behavior of alloy systems and the influence of metallurgical factors on each is available (30). Some of these factors in a few technologically important alloy systems are discussed here. 

Metallurgically influenced corrosion is mainly composed of the corrosion due to chemical composition (alloying elements, metalloids and impurities), metallurgical properties (metallic phases, grain joints) and fabrication procedures (thermal treatments, lamination and welding). Figure 6.24 shows weld zone, dealloying, exfoliation and internal modes of attack. 

Figure 6.24 Heat-affected zone and some morphlogies of metallurgically influenced corrosion3...

The second part of the book consists of two chapters namely the forms of corrosion and practical solutions. The chapter, Forms of Corrosion consists of a discussion of corrosion reactions, corrosion media, active and active-passive corrosion behavior, the forms of corrosion, namely, general corrosion, localized corrosion, metallurgically influenced corrosion, microbiologically influenced corrosion, mechanically assisted corrosion and environmentally induced cracking, the types and modes of corrosion, the morphology of corroded materials along with some published literature on corrosion. 

N.D. Greene and B.E. Wilde, Variable Corrosion Resistance of 18 Chromium-8 Nickel Stainless Steels Influence of Environmental and Metallurgical Factors, Corrosion, Vol 26, 1970, p 533-538... 

The model is capable of accurately simulating thermal behavior of steel strip cooled by an array of impinging water jets. The findings provide useful insights to a metallurgist for assessing the mechanical and metallurgical properties of steel, which are influenced by microstruc-... 

Microstructural characteristics, such as grain size and metallurgical phases (lower or upper bainite, ferrite), may influence the sensitivity of radiation damage. 

The interest in a wide range of rare earth-based intermetallic compounds, each with individual physical and metallurgical properties, presents the crystal grower with problems over and above those already encountered in discussion of the elements themselves. The use of UHV-rated environments and crucible-less techniques to minimise contamination is of paramount importance in the preparation of high purity rare earth elements. Adoption of the same stringent criteria is not always possible in the production of rare earth intermetallic compounds. The preparation technique employed has to take into account not only the physical properties of the rare earth metal, but also those of the other constituent(s) which can present equally difficult problems, e.g. the vapour pressure of molten zinc or the reactivity of molten Fe with W, a commonly used crucible material. These other constituent(s) also provide an additional potential source of contamination which can influence the quality of the compound prepared. Frequently, the main... 

The metallurgical characteristics of the aluminum oxide layer also depend on its physical metallurgy, such as defects and metallurgical structure included in the oxide layer. For instance, when intermetallic compound particles as secondary phases are exposed on the surface, a discontinuous oxide film with various defects is often produced at the metal-particle interface. This discontinuous oxide film is weakly or non-protective chemically and physically. Because corrosion is a chemical and electrochemical reaction on the surface, corrosion behavior is readily influenced by surface morphology. The aluminum surface is usually adsorbed or contaminated by water, gases and many kinds of micron-sized substances. Microscopic heterogeneous structures such as vacancies, steps, kinks, and dislocations, and macroscopic heterogeneous structures such as scratches, pits and other superficial blemishes influence the corrosion behavior of aluminum and its alloys to different extents. 

In recent decades many researchers have performed much work on the corrosion of magnesium alloys. They have studied the corrosion phenomena, the factors influencing corrosivity and the practical applications of magnesium alloys. They have also systematically studied different corrosion cases, compared the corrosion behaviours of different alloys in different environments, proposed some practical designs to avoid serious corrosion, and sununarized various effects of environmental and metallurgical factors on the corrosivity of magnesium alloys. There have, however, been very few mechanistic studies and some fundamental questions remain unanswered. These fundamental problems have potential... 

The actual mechanism of radiation embrittlement is not completely understood. For example, in low alloy RPV steel, radiation embrittlement is a function of both environmental and metallurgical variables. Fluence or dpa, and copper and nickel content have been identified as the primary contributors in US NRC Regulatory Guide 1.99, Revision 2 [5.1]. Other important variables include flux, temperature and phosphorus content. There is evidence that other variables such as heat treatment may also influence embrittlement. Therefore, mathematically based statistical data correlation are subject to uncertainty. 

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