Stress–strain Evolution in Cast in-738 Superalloy Single Fusion Welds

Bonifaz, E. A.; Richards, N.L.

doi:10.1142/s1758825110000767

Cited by 14 publications

(12 citation statements)

References 16 publications

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“…In Bonifaz and Richards [20], the mechanical model predicts highest residual stresses in regions of highest elastic strains, in agreement with conventional phenomenological material models where the macroscopic residual stress is always directly related to the macroscopic elastic strain. The highest residual stresses are located at the fusion line (where coarser dendrite secondary arm spacing exist); and the highest plastic strains are located at centerline (where finer dendrite secondary arm spacing exist).…”

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confidence: 79%

Simulaciones Multiescala en Soldaduras

Bonifaz

2012

Av. Cienc. Ing. (Quito)

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Welding processes involve complex couplings between fluid dynamics, heat transfer and the metallurgical changes experienced by the base metal. Distortion, residual stresses, grain structure, cooling rates, high temperatures and consequently the reduced strength of a structure in and around a weld joint are produced by the localized thermal cycling caused by the intense heat input of fusion welding. With the virtual prediction of weld profiles (shape and size), solidification structures, distribution of impurities, formation of dislocations, distortions and residual stresses of a welded part, processes can be optimized in the early stages of prototyping. The technological properties of fusion welds are formed due to the simultaneous effects of different physical phenomena which occur on different length scales. Correspondingly the simulation of technological properties of fusion welds requires the multiscale approach.Keywords. Residual Stresses, Voronoi Cell Finite Element Modeling (VCFEM), Welding, Solidification; Dislocations. ResumenLos procesos de soldadura involucran acoplamientos complejos entre dinámica de fluídos, transferencia de calor y los cambios metalúrgicos que experimenta el metal base. Distorsión, tensiones residuales, estructura granular, tasas de enfriamiento, altas temperaturas y consecuentemente la resistencia reducida de una estructura en y alrededor de una junta soldada, son producidos por el ciclo térmico localizado causado por la intensa entrada de calor en soldadura de fusión. Con la predicción virtual de perfiles de suelda (forma y tamaño), estructuras de solidificación, distribución de impurezas, formación de dislocaciones, distorsiones y tensiones residuales de una parte soldada, los procesos pueden ser optimizados en la etapa temprana del diseño (prototipo). Las propiedades tecnológicas de las sueldas de fusión son formadas debido a los efectos simultáneos de diferentes fenómenos físi-cos los cuales ocurren a diferentes escalas. Correspondientemente, la simulación de las propiedades tecnológicas requiere la aproximación multiescala.Palabras Clave. Tensiones residuales, Modelación Voronoi-Elementos Finitos, Soldadura, Solidificación, Dislocaciones.Fusion welding processes are widely used for general repair applications. Successful repair requires the transient heat and fluid flow phenomena of the weld pool be addressed adequately to prevent the formation of new grains, equiaxed or columnar, ahead of the epitaxial columnar dendrites. It is well known that the dynamic behaviour of weld pools, due to heat and fluid flow in the weld pool, has significant influence on the temperature distribution, shape and size of the weld pool, final solidification microstructures, and consequently the resultant mechanical properties of the welded joints [1]. It is of great significance to understand the process quantitatively, focused on modelling the transient dynamics of the weld pool, especially the transient heating period after the arc ignites and the transient cooling period after the arc e...

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confidence: 79%

Simulaciones Multiescala en Soldaduras

Bonifaz

2012

Av. Cienc. Ing. (Quito)

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“…These stresses depend on the detailed thermal history, as well as the restraints (fixturing) used during processing. 18 If appropriate sub-level physical and mechanical properties are included into a strain gradient plasticity finite element analysis, then, it will be easily verified that materials display strong size effects when the characteristic length scale associated with non-uniform plastic deformation is on the order of microns. Figure 5 shows the normal stress and normal strain contours along PATH in a global meso submodel domain.…”

Section: The Mechanical Meso-submodelmentioning

confidence: 99%

Submodeling Simulations in Fusion Welds: Part II

Bonifaz

2013

J. Multiscale Modelling

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In part I, three-dimensional transient non-linear sub modeling heat transfer simulations were performed to study the thermal histories and thermal cycles that occur during the welding process at the macro, meso and micro scales. In the present work, the corresponding non-uniform temperature changes were imposed as load conditions on structural calculations to study the evolution of localized plastic strains and residual stresses at these sub-level scales. To reach the goal, a three-dimensional finite element elastic-plastic model (ABAQUS code) was developed. The sub-modeling technique proposed to be used in coupling phase-field (and/or digital microstructures) codes with finite element codes, was used to mesh a local part of the model with a refined mesh based on interpolation of the solution from an initial, relatively coarse, macro global model. The meso-sub-model is the global model for the subsequent micro sub-model. The strategy used to calculate temperatures, strains and residual stresses at the macro, meso and micro scale level, is very flexible to be used to any number of levels. The objective of this research was to initiate the development of microstructural models to identify fusion welding process parameters for preserving the single crystal nature of gas turbine blades during repair procedures. The multi-scale submodeling approach can be used to capture weld pool features at the macro-meso scale level, and micro residual stress and secondary dendrite arm spacing features at the micro scale level.

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“…The thermal gradients calculated with the thermal model already described in our previous related research [19][20][21][22], were imposed as load conditions to calculate micro residual stresses based on the proposed multi-scale strategy. Details of the thermo-mechanical analysis can be found in the above mentioned works.…”

Section: Introductionmentioning

confidence: 99%

Modeling Fusion Welds: A Multi-Scale Submodeling Approach

Ea¹

2020

Int J Metall Met Phys

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The technological properties of fusion welds are formed due to the simultaneous effects of different physical phenomena which occur on different length scales. In the multi-scaled modelling method designed to make microstructure modelling more tractable, a fine meso sub-mesh resides in each element of a coarse macroscopic global mesh. Of the same manner, a fine micro sub-mesh resides in each element of a coarse mesoscopic global mesh. In this work, a transient non-linear multi-scale finite element heat flow-mechanical model to determine micro-residual stresses was developed. Thermal cycles calculated to predict macro, meso and micro-residual stresses, were imposed as load conditions. The numerical procedure was developed in a three-dimensional domain using the coupling DREAM.3D-ABAQUS, and the construction of ABAQUS user-defined subroutines. A non-standard domain decomposition method based on the concept of Representative Volume Elements (RVEs) was used to include the polycrystalline nature of the specimen. The micro-submodel developed to identify temperature, strain and stress contours at different step times, requires the meso temperature gradient information as prescribed driven (load) boundary conditions. A strong dependence of micro residual stresses on grain size is clearly observed.

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Stress–strain Evolution in Cast in-738 Superalloy Single Fusion Welds

Cited by 14 publications

References 16 publications

Simulaciones Multiescala en Soldaduras

Simulaciones Multiescala en Soldaduras

Submodeling Simulations in Fusion Welds: Part II

Modeling Fusion Welds: A Multi-Scale Submodeling Approach

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