Metallurgy embrittlement

Hi.S may cause hydrogen embrittlement in certain metals. Figures 7-1 and 7 -2 show the H2S concentration at which the National Association of Corrosion Engineers (NACE) recommends special metallurgy to guard against H9S corrosion. 

Stress Corrosion Cracking and Embrittlement (Electrochem. Soc. Symposium), Ed. Robertson, W. D., Wiley, New York (1956) Physical Metallurgy of Stress-Corrosion Fracture (A.I.M.E. Symposium), Ed. Rhodin, T. N., Imerscience, New York (1959) ... 

Duquette, D. J., Fundamentals of corrosion fatigue behaviour of metals and alloys , in Proc. Conf. Hydrogen Embrittlement and Stress Corrosion Cracking, Cleveland, Ohio, 1-3 June 1980, Case Western Reserve University Department of Metallurgy and Materials Science, pp. 249-70 (1980)... 

For reformer outlet manifolds the normal metallurgy choice is a wrought type of Alloy 800 H. It has sufficient ductility and thermal-shock resistance during startup and shutdown. The cast version of Alloy 800 H provides a cost-effective, alternate material with a higher creep-rupture strength, low tendency for embrittlement and good ductility. Hot reformed-gas transfer lines are usually refractory-lined with an interior of Alloy 800 sheathing88. 

Kolachev, B.A. (1999) Hydrogen embrittlement of metals (in Russian), Moscow, Metallurgy ... 

J. P. Momiroli, Low Tenrperature Embrittlement of Undoped and Doped Timgsten, in The Metallurgy of Doped/Non-sag Tungsten (E. Pink and L. Baiha, eds.), Elsevier, London (1989). 

Jer] Jemberg, P., Waeppling, R., A Mdssbauer Study of the 6 Phase in the Fe-W-C System , J. Solid State Chem., 49 (1), 123-125 (1983) (Crys. Stracture, Experimental, 5) [1983Kwo] Kwon, H., Kim, C.H., Tempered Martensite Embrittlement in Fe-Mo-C and Fe-W-C Steel , Metall. Trans. A (Physical Metallurgy and Materials Science), 14A(7), 1389-1394 (1983) (Morphology, Experimental, Meehan. Prop., 16)... 

In conventional steels, too much phosphorus causes embrittlement by grain boundary segregation, and its concentration is therefore nsnaUy limited to <0.05%. Powder metallurgy, on the other hand, allows larger amounts to be nsed in sintering techniques which can optimise characteristics such as tensile strength. 

Refinery management, 524-525 Refinery metallurgy, 415-429 metals used in refinery service, 415-416 stainless steel nomenclature, 416-418 corrosion resistance, 417, 419—426 embrittlement dangers, 426 rigorous service, 426-427 heat-exchanger tube fouling, 428 troubleshooting problems, 428... 

Today different high-quality grades are assured by improved metallurgy. Table 1-6. Corrosion resistance can be improved by addition of Mo, Cu, W and N. Nitrogen as an austenite stabilizer reduces precipitation of the a-phase. Overall, the precipitates in Duplex steels can be very complex. Beside the high temperature phases (a-phase, T-phase, Cr2N-nitride, M23C6) a 475 °C embrittlement can occur (Schlapfer and Weber, 1986 ... 

Several testable models for stress-corrosion cracking (SCC) of metals are discussed in terms of the main experimental variables stress, metallurgy, and environment. Slip-dissolution, film-induced cleavage, and hydrogen embrittlement models are all shown to be consistent with experimental data in particular systems. Other models that cite effects of corrosion (without a film) or adsorption on crack tip deformation, leading to microcleavage or plastic microfracture, are less easy to test. No model can be universal in view of the demonstrable multiplicity of mechanisms. In many cases the atomistic mechanism is unknown, yet cracking can be controlled or predicted via the localized corrosion process that precedes SCC. 

Embrittlement (metallurgy) The reduction in fracture toughness of a material by the addition of impurity atoms, such as hydrogen or helium in high strength steel, or mercury or indium in aluminum. 

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