A 3D continuum crystal plasticity model is used to simulate the material behavior of a directionally solidified Ni-base superalloy, DS GTD111, with application to uniaxial loading in the longitudinal and transverse orientations. Isothermal uniaxial fatigue tests with hold times and creep tests are conducted at temperatures ranging from room temperature (RT) to 1038 °C to characterize the deformation response. The constitutive model is implemented as a User MATerial subroutine (UMAT) in ABAQUS and a parameter estimation scheme is developed to obtain the material constants. Both in-phase and out-of-phase thermo-mechanical fatigue tests are conducted and modeled. An anisotropic damage model is used to model the tertiary creep response in both the longitudinal and transverse orientation, which is calibrated using the experimental creep data.

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Constitutive Modeling and Life Prediction in Ni-Base Superalloys

Life modeling of anisotropic fatigue behavior for a single crystal nickel-base superalloy

Fatigue life modeling of a single crystal superalloy and its thin plate with a hole at elevated temperature

An anisotropic elastic–plastic model for predicting the rafting behavior in Ni-based single crystal superalloys

A phase field model of grain boundary migration and grain rotation under elasto–plastic anisotropies

Taking into account the effects that the components of tension stresses couple with components of torsion stresses when off-axis loads are applied to orthotropic materials, Hill’s yield criterion for plastically orthotropic solids is modified by adding an invariant that is composed of the product item of quadratic components of the deviatoric stress tensor, and a new yield criterion is put forward in terms of the characteristics of the face-centered cubic (FCC) single-crystal material. The correlation of prediction and experiments is very good, and the new criterion is used to predict the yield stresses of an internal single-crystal, Nickel-based superalloy, DD3, which is more accurate than that of Hill’s at 760°C. Equivalent stress and strain that adapt to the new criterion are defined. Thinking of the yield function as a plastic potential function from the associated flow rule, the elastic-plastic constitutive model for the FCC single-crystal material is constructed, and the corresponding elastic-plastic matrix is educed. The new yield criterion and its equivalent stress and strain will be reduced to Von Mises’ yield criterion and corresponding equivalent stress and strain for isotropic materials.

Constitutive Model for an FCC Single-Crystal Material

In order to accurately predict the temperature field of rolled pieces,optimize the hot rolling process and improve the quality of the final product,the finite element temperature model of 3104 aluminum alloy plate during single pass hot rollig process was built up using MSC,Marc softwares by rolling test and two-dimensional elastoplastic finite element method.The effects of air cooling,contact heat transfer,plastic deformation heat and friction heat on the plate temperature were investigated.And the effects of rolling parameters including the initial temperature of plate rolling speed,contact heat transfer coefficient and reduction on temperature drop sensitivity coefficient were analyzed also.The results show that contact heat transfer had the most effect on the plate temperature and it was followed by plastic deformation,friction and air cooling.The initial temperature had the most effect on the temperature drop sensitivity coefficient and it was followed by rolling speed,contact heat transfer coefficient and reduction.

Temperature Simulation of Single Pass Hot Rolling Process of Aluminum Alloy

Taking into account the effects that the components of tension stresses coupled with components of torsion stresses when off-axis loads are applied for orthotropic material, Hill's yield criterion for plastically orthotropic solids is modified by adding an invariant which is composed of quadratic components of deviatoric stress tensor, then a new yield criterion is put forward in term of the characteristics of face-centered cubic (FCC) single crystal material The correlation to experimental results is very good while the new criterion is used to predict the yield stresses of single crystal nickel-based superalloy DD3,and it is more accurate than Hill's at 760 ℃ The equivalent stress and strain which adapt to the new criterion are defined Thinking of the yield function as a plastic potential function according to the associated flow rule, the elastic-plastic constitutive model for FCC single crystal material is constructed and the corresponding elastic-plastic matrix is educed The new yield criterion and its equivalent stress and strain will be reduced to Von Mises yield criterion and the corresponding equivalent stress and strain for isotropic material respectively

Constitutive model for FCC single crystal material

In hot tandem mill process, aluminum strip steering is external manifestation, which is lateral asymmetric of rolling parameters. the paper extract lateral asymmetric characteristics of rolling parameters and study mutual functional relation of several feature parameters and transformation compensation relationship of lateral asymmetric characteristics between strip delivery thickness and strip delivery speed, and build the explicable mechanism model of strip steering. On the basis of explicable mechanism model, we can solve for the model of strip steering trajectory and the model of strip steering direction. According to the model of strip steering trajectory, we can calculate to get time-dependent strip steering quantity after strip is out of rolling area. According to the model of strip steering direction, we can judge the direction of strip steering by the direction of each disturbing quantity or the change of on-line observable bilateral roll force error, which provide theoretical support for strip steering control.

The Modeling of Trajectory Deviation and Deviation Direction in Aluminum Hot Tandem Mill

Because of the balance of forces in cathode carbon block assembling process, the interaction between particles affects the microscopic and macroscopic behavior of the ramming paste, which leads to agglomeration and breakage Six types of particle interactions in two-body system are summarized: capillary forces, van der Waals forces, viscous forces, contact forces, electrostatic force and the forces of gravity Through comparison of the magnitude of these interaction forces, the forces that have immediate effect on the coalescence and breakage behaviors of the carbon paste are obtained The effects of the particle size on the interparticle forces of carbon paste are discussed At last, the variations of these forces over time in a collision process were studied and the agglomeration mechanism during collisions was then analyzed mechanically by investigating the relative magnitudes of the two forces during the collision process

Liu Yi-lun

Papers

Constitutive Model for an FCC Single-Crystal Material

Temperature Simulation of Single Pass Hot Rolling Process of Aluminum Alloy

Constitutive model for FCC single crystal material

The Modeling of Trajectory Deviation and Deviation Direction in Aluminum Hot Tandem Mill

Interparticle forces in viscous ramming paste and it's mechanism analysis