Constant load creep tests on isothermally forged Udimet 720Li, an advanced superalloy for gas turbine disc application, were run in the stress/temperature field 900-450MPa/650-700 ℃ producing rupture times in the 20-...Constant load creep tests on isothermally forged Udimet 720Li, an advanced superalloy for gas turbine disc application, were run in the stress/temperature field 900-450MPa/650-700 ℃ producing rupture times in the 20-5000h range. The creep curves have shown a predominant accelerating creep stage, that has been described by the following equation: where ε min depends on stress and temperature, while parameter C depends mainly on stress. A strain dependent damage, defined by the parameter C, causes the accelerating creep stage at stresses lower than 750MPa, whilst its contribution to the creep strain acceleration is less important at higher stresses. The model rationalizes the different behaviors at high and low stress and has been validated with variable stress and temperature creep behavior.展开更多
The creep behavior of the γ TiAl base alloy has been investigated in the stress range 125～490 MPa at temperatures from 650 to 800 ℃ in three materials having different silicon content. The improved creep resistance...The creep behavior of the γ TiAl base alloy has been investigated in the stress range 125～490 MPa at temperatures from 650 to 800 ℃ in three materials having different silicon content. The improved creep resistance in Si rich material is attributed to the interaction between silicide precipitates and dislocations. Nearly lamellar microstructure exhibits better creep resistance than duplex material.展开更多
文摘Constant load creep tests on isothermally forged Udimet 720Li, an advanced superalloy for gas turbine disc application, were run in the stress/temperature field 900-450MPa/650-700 ℃ producing rupture times in the 20-5000h range. The creep curves have shown a predominant accelerating creep stage, that has been described by the following equation: where ε min depends on stress and temperature, while parameter C depends mainly on stress. A strain dependent damage, defined by the parameter C, causes the accelerating creep stage at stresses lower than 750MPa, whilst its contribution to the creep strain acceleration is less important at higher stresses. The model rationalizes the different behaviors at high and low stress and has been validated with variable stress and temperature creep behavior.
文摘The creep behavior of the γ TiAl base alloy has been investigated in the stress range 125～490 MPa at temperatures from 650 to 800 ℃ in three materials having different silicon content. The improved creep resistance in Si rich material is attributed to the interaction between silicide precipitates and dislocations. Nearly lamellar microstructure exhibits better creep resistance than duplex material.
