The steady state creep rate equdtion ofa nickel base superalloy Inconel 718, strengthenedby coherent ordered disc-shaped bct γ<sup>11</sup> phaseand coherent spherical fcc γ<sup>1</sup> phase...The steady state creep rate equdtion ofa nickel base superalloy Inconel 718, strengthenedby coherent ordered disc-shaped bct γ<sup>11</sup> phaseand coherent spherical fcc γ<sup>1</sup> phase precipitates,has been established in the stress and temperatureranges of 620-840 MN m<sup>-2</sup> and 853-943K, respecti-vely. Constant stress tensile creep tests wereused to medsure the values of steady state creeprate, ε<sub>s</sub>, and the consecutive stress reductionmethod was used to measure the back stress duringcreep deformation. The values of effective stressexponent, n<sub>e</sub>, were detemined from the slopesof the lgε<sub>s</sub> vs. lg（σ<sub>a</sub>-σ<sub>0</sub>）/G plots. The effectof grain size, d, on steady state creep rdtehas been also studied in this investigation,and the grain size sensitive exponents m weredetemined from the slopes of lgε<sub>s</sub> vs. lg（b/d）plots. The creep rate equations of Inconel 718,in the above stress and temperature ranges,have been proposed to beε<sub>s</sub>=1.6×10<sup>-5</sup>（D<sub>1</sub>Gb/KT） （b/d ）<sup>0.19</sup>[（σ<sub>a</sub>-σ<sub>0</sub>）/G]<sup>1.35</sup>in diffusional creep region, andε<sub>s</sub> =75（D<sub>1</sub>Gb/KT） （b/d）<sup>-0.42</sup>[（σ<sub>a</sub>-σ<sub>0</sub>）/G]<sup>5.5</sup>in dislocation power law creep region.展开更多
文摘The steady state creep rate equdtion ofa nickel base superalloy Inconel 718, strengthenedby coherent ordered disc-shaped bct γ<sup>11</sup> phaseand coherent spherical fcc γ<sup>1</sup> phase precipitates,has been established in the stress and temperatureranges of 620-840 MN m<sup>-2</sup> and 853-943K, respecti-vely. Constant stress tensile creep tests wereused to medsure the values of steady state creeprate, ε<sub>s</sub>, and the consecutive stress reductionmethod was used to measure the back stress duringcreep deformation. The values of effective stressexponent, n<sub>e</sub>, were detemined from the slopesof the lgε<sub>s</sub> vs. lg（σ<sub>a</sub>-σ<sub>0</sub>）/G plots. The effectof grain size, d, on steady state creep rdtehas been also studied in this investigation,and the grain size sensitive exponents m weredetemined from the slopes of lgε<sub>s</sub> vs. lg（b/d）plots. The creep rate equations of Inconel 718,in the above stress and temperature ranges,have been proposed to beε<sub>s</sub>=1.6×10<sup>-5</sup>（D<sub>1</sub>Gb/KT） （b/d ）<sup>0.19</sup>[（σ<sub>a</sub>-σ<sub>0</sub>）/G]<sup>1.35</sup>in diffusional creep region, andε<sub>s</sub> =75（D<sub>1</sub>Gb/KT） （b/d）<sup>-0.42</sup>[（σ<sub>a</sub>-σ<sub>0</sub>）/G]<sup>5.5</sup>in dislocation power law creep region.
