Ni基超耐熱合金Waspaloyにおける析出物の挙動

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In Ni-base superalloys, mechanical and chemical properties of welded joints depend on the behavior of precipitates such as γ' phase, M_<23>C_6 etc. The susceptibilities of solidification cracking, liquation cracking, reheat cracking etc. are also influenced by the behavior of precipitates. In the present study, the behavior of precipitates in Waspaloy has been researched to get fundamental information about the behavior of minor phases during welding in Ni-base superalloys. Main results obtained in this study are as follows ; 1) Intergranular M_<23>C_6 carbides, intragranular γ' phases and massive TiC were observed in base metal (1080℃×4 hr, W.Q.). 2) Precipitated zone heated up to 700-900℃ was formed in HAZ. Precipitation of γ' phase and M_<23>C_6 carbide was promoted in this region. 3) During isothermal heat treatment ; a) Heat treatment at 900-1000℃ resulted in most rapid precipitation of M_<23>C_6. b) γ' phase most rapidly precipitated at about 900℃ and γ' phase coarsening was found to obey Lifschitz-Wagner theory. c) It was found that increment of hardness by γ' phase precipitation, ΔHv was a linear function of (aging time, t)^<1/6> within experimental error. 4) During weld thermal cycle ; a) M_<23>C_6 carbide precipitated at 750-950℃ during welding. b) Incipient melting of TiC was observed at the temperature more than 1270℃. c) γ' phase precipitated at 900-980℃ during welding. d) γ' phase coarsened in the temperature range from 1000℃ to 900℃. e) Hardness was a function of cooling time from 1000℃ to 700℃. 5) It was possible to estimate hardness of solution treated material during post weld heat treatment by using the relation between ΔHv and t^<1/6>.
社団法人溶接学会の論文
1985-11-05

Ni基超耐熱合金Waspaloyにおける析出物の挙動

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