Ni 基耐熱合金の溶接後熱処理割れに関する研究(第 1 報) : 溶接後熱処理割れの特徴とγ' 相の析出挙動

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In this study, the criterion of post-weld heat treatment (PWHT) cracking was considered in accordance with the features of PWHT cracking and precipitation behaviors of γ' phase were also examined. The results obtained in this study are as follows; 1) Typical PWHT crackings of Ni-base heat resistant alloys usually initiate at coarse grain boundaries adjacent to the weld interface where residual stress concentrates. Consequently, the deformability of material in stress concentrated region is presumed to be closely related to the PWHT cracking susceptibility. 2) γ' phase precipitates very rapidly in the temperature range from 800℃ to 900℃. Each shortest incubation time of γ' phase precipitation in Heats 702A and 722A is about 8sec at 900℃ and 80sec at 800℃ respectively. 3) From the kinetics of aging, coarsening of γ' phase is obeyed with the theory of Ostwald ripening and controlled by the diffusion process of Al in matrix.
社団法人溶接学会の論文
1978-02-05