TAILIEUCHUNG - Handbook Corrosion (1992) WW Part 8

Tham khảo tài liệu 'handbook corrosion (1992) ww part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Hydrochloric acid 10 35 95 340 650 Ti-8Al-1Mo-1V Red Fuming Nitric Acid. The first reported observation of titanium SCC occurred in red fuming nitric acid Ref 156 . Cracking was observed for commercially pure titanium in a room-temperature environment containing 20 NO2. Later investigators indicated that SCC occurred in as little as NO2 with less than H2O. Intergranular cracking was observed on smooth specimens which indicates the high sensitivity to SCC in this medium. In addition to commercially pure titanium cracking was observed on Ti-8Mn and Ti-6Al-4V even in red fuming HNO3 without free NO2. Work on inhibitors showed than to H2O completely inhibits SCC. It was also shown that 1 NaBr inhibits SCC Ref 156 . The work on water as an inhibitor is especially interesting because it is of importance in a number of other environments that promote SCC. Nitrogen Tetroxide. As titanium use in aerospace increased it was found that titanium alloys were highly resistant to corrosion attack in nitrogen tetroxide N2O4 an oxidizer used with hydrazine rocket fuels. Unfortunately SCC was rather dramatically revealed in an explosion during proof testing of a Ti-6Al-4V storage vessel. The vessel that exploded had been exposed to N2O4 at 40 C 100 F at a stress level of 620 MPa 90 ksi . Testing revealed that titanium alloys would crack in NO-free N2O4 that is N2O4 with excess dissolved oxygen or red N2O4 but would not crack in NO-containing N2O4 oxygen free or green N2O4 Ref 127 . Methanol. Prior to the discovery of SCC in N2O4 methanol was found to cause stress cracking of titanium alloys. Methanol and NaBr were shown to be extremely corrosive to titanium and in some cases they promoted intergranular SCC of smooth specimens Ref 157 . Soon after this discovery it was shown that methanol HCl and methanol H2SO4 mixtures also caused SCC of commercially pure titanium--once again on smooth specimens Ref 158 . Stress-corrosion cracking in methanol was .

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