Effects of Withdrawal Rate during Thermally-controlled Solidification on Microstruc-ture and Endurance Property of Equiaxed Ni-based Superalloy
Superalloy is widely used in the manufacture of engine turbine blades and thermal end parts of complex struc-tures due to the excellent casting properties and comprehensive mechanical properties.Effects of withdrawal rate on heat-treated structure and endurance property of a novel equiaxed superalloy by thermally-controlled solidification at 1 050℃and 120 MPa were investigated.The results indicate that the content of shrinkage porosity in the alloy is increased with the increase of withdrawal rate,while the grain size and γ/γ' eutectic are decreased significantly,pro-moting the formation and growth of γ' phase in dendrite stem.The enduring rupture property of alloy is significantly reduced at 1 050℃and 120 MPa with increase of withdrawal rate.Finally,the decrease of enduring rupture property is attributed to refinement of grain size,the increasing degree of γ' phase rafting,the rapid initiation of microcracks caused by shrinkage porosity and retarding effect reduction of broken carbide on crack extension.
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