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Hot corrosion behavior of three different zones of linear friction welded Ti‐22Al‐25Nb alloy
Author(s) -
Chen Xi,
Xie Faqin,
Ma Tiejun,
Li Wenya,
Wu Xiangqing
Publication year - 2019
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.201810356
Subject(s) - base metal , corrosion , metallurgy , welding , materials science , dissolution , joint (building) , alloy , metal , sulfur , base (topology) , diffusion , pitting corrosion , chemistry , architectural engineering , mathematical analysis , physics , mathematics , engineering , thermodynamics
Ti‐22Al‐25Nb joint was achieved by using linear friction welding (LFW) technique. The hot corrosion behavior of base metal, weld zone, and thermo‐mechanically affected zone (TMAZ) was investigated at 700 °C in 25% NaCl‐75% Na 2 SO 4 (wt%) mixed molten salt. In the initial stage, the base metal and joint exhibit similar oxidation resistant ability, and the corrosion products formed on all zones are mainly composed of TiO 2 , Nb 2 O 5 , and Al 2 O 3 . The formation of NaNbO 3 first occurs in base metal and TMAZ after 50 h, while the weld zone is free of NaNbO 3 until 100 h. The development of pitting corrosion in both base metal and TMAZ is caused by the diffusion of sulfur and re‐oxidation of sulfides. After a prolong exposure in molten salts, more serious sulfuration, acid dissolution, and escape of gaseous chlorides occurred in base metal leading to a drastic acceleration of corrosion rate.