Behavior of sensitized AlSl types 321 and 347 austenitic stainless steels in hydrogen
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tenitic matrix, resulting in the formation of several carbides and intermetallic phases. The thermally activated processes of hydrogen diffusion in wall materials such as stainless steels and INCONELs* and of its surface re-
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error. It is noteworthy that the interactions ot boron Wlt[q ~u and A1 are not very strong. In Cu, the limiting enthalpy of mixing of liquid boron I91 in dilute solution is + 7 kJ/mol B, and there is no stable solid boride. A1B2 solid exists but melts incongruently at 975 ~ The transition metals which show depressions of freezing point corresponding to monomeric boron have very stable solid borides, implying strong interaction. It is, thus, plausible that boron interacts with itself to form dimers when there is insufficient attraction to the solvent atoms. Perhaps the broadest lesson to be drawn from this work is that, although usually H e n r y ' s law is applicable in dilute solutions, if enough data exist to make a check, it is a wise precaution to do so. Indeed, Henry's law is applicable in this case, but only if one takes the boron as dimerized. In solutions sufficiently dilute, it must dissociate, but that condition has not yet been reached at the level of parts per million.
REFERENCES I. A.A. Abdel-Hamid and F. Durand: Metall. Trans. A, 1986, vol. 17A, p. 349. 2. G.K. Sigworth: Metall. Trans. A, 1986, vol. 17A, pp. 349-51. 3. A. Abdel-Hamid and F. Durand: Mdm. Sci. Rev. Mdt., 1983, vol. 10, pp. 591-96. 4. N.J. Finch: Metall. Trans., 1972, vol. 3, pp. 2709-11. 5. A. Cibula: Metall. Trans., 1972, vol. 3, pp. 751-53. 6. F. Morimune, H. Shigu, K. Kobayaski, and R. Ozaki: J. Jpn. Inst. Met., 1977, vol. 41, pp. 444-50. 7. T.B. Massalski: Binary Alloy Phase Diagrams, ASM, Metals Park, OH, 1986, vol. 1. 8. D.J. Chakrabarti and D.E. Laughlin: Bull. Alloy Phase Diagrams, 1982, vol. 3 (1), pp. 45-48. 9. S. Sato and O.J. Kleppa: J. Chem. Thermodyn., 1982, vol. 14, pp. 133-43.
Behavior of Sensitized AISI Types 321 and 347 Austenitic Stainless Steels in Hydrogen P. ROZENAK and D. E L I E Z E R Austenitic stainless steels are presently used for wall material applications which require good mechanical properties and corrosion resistance. The welding process and long-time exposure of these steels to elevated temP. R O Z E N A K , Lecturer, and D. ELIEZER, Professor and Department Head, are with the Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel. Manuscript submitted September 6, 1988. METALLURGICAL TRANSACTIONS A
lease piav an essential role in the i~,:.~,-r~-~. . . . . many tuslon Oevlces.'" •owever, oata on me Y [ ] ! c r o structural effects of the stainless steels in hydrogen environments are scarce. Sensitization takes place in the temperature range from about 500 ~ to 950 ~ in austenitic stainless stee
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