EFFECT OF LONG-TERM AGING ON DYNAMIC TENSILE DEFORMATION BEHAVIOR OF GH4169 ALLOY

In traditional aeroengine manufacturing industry,the variation and mechanism of the mechanical property of superalloy used for rotating parts under the actual dynamic load is not given full considerations during its structure design.The mechanical property and deformation behavior of the alloys under the dynamic load have significant difference compared with that under the static load, and therefore the study on the deformation behavior of the alloy under the dynamic load is important for the safety of rotating parts used under the severe service conditions.The effect of microstructural changes of long-term aging GH4169 alloy on the mechanical properties through tensile testing at strain rates ranging from 10~1 to 10~3 s~(-1) was examined in this paper.The tensile deformation behavior of the alloy and the mechanisms were also discussed.The results showed that the strength of the alloy depends strongly on the aging time,the fracture elongation decreases with the increasing aging time and remains unchanged when aged for 500 h when tensile tested at the strain rates ranging from 10~1 to 10~3 s~(-1).And when the strain rate is high up to 10~3 s~(-1),the elongation depends strongly on the aging time and the degradation of ductility by the long-term aging happens ahead of time,but the aging time has no obvious effect on the strength of the alloy.Through tensile testing at the strain rate of 10~3 s~(-1),it is too late to release the blocked dislocation motion in the way of dislocation decomposition or climb in the alloy.And there is no peaking size effect of the strengthening phase in the alloy with the aging time ranging from 0 to 1000 h and there is no obvious effect of the aging time on the strength of the alloy.The ability of accommodation of plastic deformation by grain boundaries reduces under the dynamic loads due to the existence of precipitate free zones aroundδphase at the grain boundary in the alloy by long-term aging,and thus the ductility of the alloy by aging for a shorter time decreases rapidly when tensile tested at the strain rate of 10~3 s~(-1).