焼結 Ni 基超耐熱合金粉末押出し材の超塑性挙動と最適加工プロセス

概要

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The powder of nickel-base superalloy Mod. IN-100 was consolidated by hot isostatic pressing and recrystallized under the conditions of extrusion ratio of 72% at 1373K and subsequent annealing at 1343K×1h. The fine grain size of 1.5μm in diameter was obtained. The superplastic behaviour of alloy bars mentioned above was investigated in the temperature range of 1223∿1423K and in the range of strain rates from 2.5×10^<-4> to 10^<-1>s^<-1>. The ln σ vs. ln ε^^. curves were obtained. It was shown that the conditions obtaining the maximum strainrate sensitivity index, m changed from the constant strain rate of 10^<-2>s^<-1> at temperatures above 1303K to the constant flow stress of 150 MPa below 1303K. Therefore, it was possible to divide the ln σ vs. ln ε^^. curves into six regions according to the deformation behaviour. Furthermore, it was desirable to decrease the temperature continuously for the purpose of keeping the maximum m during superplastic deformation in tensile test. In fact, the total elongation exceeded extremely as compared with the isothermal test.
社団法人日本鉄鋼協会の論文
1988-01-01