Ni基単結晶合金CMSX-4の高温疲労き裂進展挙動とその破壊解析

概要

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In-situ observation on fatigue crack growth behavior in single crystal Ni-base superalloy CMSX-4 in vacuum at 700℃ and 800℃ was studied with a special view of mesoscopic fracture analysis. Especially, influences of γ' precipitates on high temperature fracture mode of CMSX-4 were examined. The main results obtained were as follows; (1) There was an obvious difference between fatigue crack propagation (FCP) behaviors at 700℃ and at 800℃. Since FCP at 700℃ was in a brittle manner, FCP diagram could not be obtained. FCP at 800℃ was stable and FCP property was controlled with Paris' law. ΔK_th was not found in FCP diagram at 80O℃, since roughness-induced closure could not be occured in this material and oxide-induced closure could not be occured in vacuum. (2) Fracture mode at 700℃ and 800℃ was consisted of two types as FCP and slip plane decohesion (SPD). A change from FCP to SPD at 700℃ was earlier than that at 800℃, since strength ofγ' precipitates at 800℃ was higher than that at 700℃. with a mesoscopic view, fracture mode of CMSX-4 was mainly dominated by strength of γ' precipitates.
一般社団法人日本機械学会の論文
1996-05-25