The control of grain size in superalloys is critical in the manufacture of gas turbine blades.The aim of the present research is to provide the technology for producing complicated hollow turbine blades with fine surf...The control of grain size in superalloys is critical in the manufacture of gas turbine blades.The aim of the present research is to provide the technology for producing complicated hollow turbine blades with fine surface grains and better comprehensive mechanical properties.By melt superheating treatment and coating the internal surfaces of shell mould using a cobalt aluminate-bearing coating material,the in-uence of cobalt aluminate as inoculant on the surface grain sizes of turbine blade was studied with addition of cobalt aluminate:0,35%,45%-65% and 100% respectively.At the same time,the effects of cooling circumstances of the blades on surface grain sizes were also experimented under the same addition of cobalt aluminate.The results showed that the melt superheating treatment plays a significant role in the grain size and carbide morphology;and fine surface grains were obtained when the internal surfaces of shell mould were coated using cobalt aluminate coatings.When the addition of cobalt aluminate in coating is between 45%-65%,and the melt is poured into preheated shell moulds with fine silica sand as backing sand,the blades satisfied the surface grain size requirement is over 90%.In addition,comparisons of the surface grain size and the mechanical properties were also conducted between home-made and foreign-made blades.展开更多
Surface nano-crystallization techniques have been recently developed as one of the most effient ways to optimize materials'structure,and therefore develop the local and global mechanical behavior as to increase st...Surface nano-crystallization techniques have been recently developed as one of the most effient ways to optimize materials'structure,and therefore develop the local and global mechanical behavior as to increase strength without compromising ductility.In this work,we present a constitutive model incorporating grain refinement hardening to simulate the nano-crystallization technique,specifically,surface mechanical attrition treatment.The computation is implemented using user-defined VUMAT subroutines.As an example of its application,a geometry model with full coverage of random impacts are employed.The results show that the model has rather precise predictability of grain size evolution during plastic deformation.The readily embedded with a computational code of material dynamics enables this novel model to be a promising tool to study the dynamic evolution of microstructures under plastic deformation.展开更多
文摘The control of grain size in superalloys is critical in the manufacture of gas turbine blades.The aim of the present research is to provide the technology for producing complicated hollow turbine blades with fine surface grains and better comprehensive mechanical properties.By melt superheating treatment and coating the internal surfaces of shell mould using a cobalt aluminate-bearing coating material,the in-uence of cobalt aluminate as inoculant on the surface grain sizes of turbine blade was studied with addition of cobalt aluminate:0,35%,45%-65% and 100% respectively.At the same time,the effects of cooling circumstances of the blades on surface grain sizes were also experimented under the same addition of cobalt aluminate.The results showed that the melt superheating treatment plays a significant role in the grain size and carbide morphology;and fine surface grains were obtained when the internal surfaces of shell mould were coated using cobalt aluminate coatings.When the addition of cobalt aluminate in coating is between 45%-65%,and the melt is poured into preheated shell moulds with fine silica sand as backing sand,the blades satisfied the surface grain size requirement is over 90%.In addition,comparisons of the surface grain size and the mechanical properties were also conducted between home-made and foreign-made blades.
基金the Shanghai UniversityUniversity of West Florida+5 种基金City University of Hong KongShanghai Institute of Applied Physicsthe Research Center of AREVA NPGE Research for the financial supportShenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park Project:HZQB-KCZYB-2020030RGC&GRF:Hong Kong General Research Fund(GRF)Scheme(CityU 11247516)。
文摘Surface nano-crystallization techniques have been recently developed as one of the most effient ways to optimize materials'structure,and therefore develop the local and global mechanical behavior as to increase strength without compromising ductility.In this work,we present a constitutive model incorporating grain refinement hardening to simulate the nano-crystallization technique,specifically,surface mechanical attrition treatment.The computation is implemented using user-defined VUMAT subroutines.As an example of its application,a geometry model with full coverage of random impacts are employed.The results show that the model has rather precise predictability of grain size evolution during plastic deformation.The readily embedded with a computational code of material dynamics enables this novel model to be a promising tool to study the dynamic evolution of microstructures under plastic deformation.
