Metallurgical variability

Fatigue Life. The formulas for estimating fatigue life are more complex and usually require several assumptions. Without attempting to evaluate the merit of such formulas, it is suggested here that alloy selection or metallurgical variables operating within an alloy may... 

Single-phase a-brasses are susceptible to stress-corrosion cracking in the presence of moist ammonia vapour or certain ammonium compounds Here the predominant metallurgical variable is alloy composition, and in... 

It is notable that while it is possible to produce maraging steels with consistently uniform mechanical properties, the stress corrosion properties are subject to scatter, as indicated in Fig. 3.34. To a large extent this scatter is an indication of the greater sensitivity of s.c.c. resistance to metallurgical variables. Although the variation in cracking resistance is not well understood, and the reaction to certain treatments not always consistent, certain observations may be used to indicate guidelines for improved properties. 

The susceptibility of nickel alloys, principally Alloys 600 and 800 to stress-corrosion in water-cooled nuclear reactor heat-exchanger circuits has received much attention. The influence of both metallurgical variables (e.g. alloy composition, heat-treatment) and water chemistry (additives, inhibitors) have been extensively studied and reviewed. ... 

Hydrogen embrittlement in single-phase austenitic stainless steels has been primarily correlated with two metallurgical variables alloy composition and the presence of second phases, such as ferrite and martensite. Ferrite can be present in austenitic stainless steels as a result of material processing, while martensite can be induced by mechanical straining. Both ferrite and strain-induced martensite render austenitic stainless steels more vulnerable to hydrogen embrittlement. The ferrite... 

The previous sections provided general guidance on materials for hydrogen gas service and emphasized the metallurgical variables that influence hydrogen embrittlement. This section describes additional factors that impact hydrogen embrittlement, primarily environmental and mechanical-loading conditions. 

Thompson, A.W. and Bernstein, I.M., The role of metallurgical variables in hydrogen-assisted environmental fracture, in Advances in Corrosion Science and Technology, Vol. 7, Fontana, M.G. and Staehle, R.W., Eds., Plenum Press, New York, 1980, pp. 53-175. 

Fig. 15. Elastic constants of Fe-13Cr-19Mn. As in Figs. 12 and 13, E and G show parallel behavior vs. temperature. Other metallurgical variables such as pressure, alloying, etc., tend to affect E and G similarly.

J. J. Noel, Effects of metallurgical variables on aqueous corrosion, in ASM Handbook, Vol. 13A, Corrosion Fundamentals, Testing, and Protection, ASM International, Materials Park, OH, 2003, p. 259. 

Another test for DFBR was conducted to clear the relationship between creep rupture strength and metallurgical variables such as chemical composition, grain size and production process. 

Thompson, Bernstein and Pressouyre [20,52] discuss the significance of a number of metallurgical variables (including chemical composition), microstructural components (precipitates, grain size and shape, crystallographic texture), heat treatment and its effects on these variables, and processing, especially thermomechanical treatments for enhancement/ optimization of properties. 

Glass JT, Cahen JGL, Stoner GE, Taylor EJ (1987) The effect of metallurgical variables on the electrocatalytic properties of PtCr alloys. J Electrochem Soc 134(l) 58-65... 

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. 

A. W. Thompson and 1. M. Bernstein, The role of metallurgical variables in hydrogen assisted environmental fracture, Rockwell Science Center Report SCPP-75-63,1975. J. P. Hirth, A/eto//. Trans. IIA 861-890 (1980). 

Therefore, the competition to create the first sub- damage is between these two factors persistent slip bands and slips activated by surface roughness. Persistent slip bands formation in just one or few surface grains is related to metallurgical variability while surface roughness depends on metal working conditions. The presence, non-eliminable, of inclusions and second-phase particles introduces a third element of competition related, like persistent slip bands, to metallurgical variability. 

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