Measuring the effect of environment on fatigue crack-wake plasticity in aluminum alloy 2024 using electron backscatter diffraction

2008 ◽  
Vol 494 (1-2) ◽  
pp. 36-46 ◽  
Author(s):  
V.K. Gupta ◽  
S.R. Agnew
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Crack ◽  
Electron Backscatter Diffraction ◽  
Crack Wake ◽  
Electron Backscatter ◽  
Aluminum Alloy 2024 ◽  
Backscatter Diffraction

scholarly journals Crack nucleation using combined crystal plasticity modelling, high-resolution digital image correlation and high-resolution electron backscatter diffraction in a superalloy containing non-metallic inclusions under fatigue

2016 ◽  
Vol 472 (2189) ◽  
pp. 20150792 ◽  
Author(s):  
Tiantian Zhang ◽  
Jun Jiang ◽  
Ben Britton ◽  
Barbara Shollock ◽  
Fionn Dunne
Keyword(s):  
Fatigue Crack ◽  
Crystal Plasticity ◽  
Electron Backscatter Diffraction ◽  
Crack Nucleation ◽  
Image Correlation ◽  
Fatigue Crack Nucleation ◽  
Resolution Electron ◽  
Electron Backscatter ◽  
Mechanistic Basis ◽  
Backscatter Diffraction

A crystal plasticity finite-element model, which explicitly and directly represents the complex microstructures of a non-metallic agglomerate inclusion within polycrystal nickel alloy, has been developed to study the mechanistic basis of fatigue crack nucleation. The methodology is to use the crystal plasticity model in conjunction with direct measurement at the microscale using high (angular) resolution-electron backscatter diffraction (HR-EBSD) and high (spatial) resolution-digital image correlation (HR-DIC) strain measurement techniques. Experimentally, this sample has been subjected to heat treatment leading to the establishment of residual (elastic) strains local to the agglomerate and subsequently loaded under conditions of low cyclic fatigue. The full thermal and mechanical loading history was reproduced within the model. HR-EBSD and HR-DIC elastic and total strain measurements demonstrate qualitative and quantitative agreement with crystal plasticity results. Crack nucleation by interfacial decohesion at the nickel matrix/agglomerate inclusion boundaries is observed experimentally, and systematic modelling studies enable the mechanistic basis of the nucleation to be established. A number of fatigue crack nucleation indicators are also assessed against the experimental results. Decohesion was found to be driven by interface tensile normal stress alone, and the interfacial strength was determined to be in the range of 1270–1480 MPa.

scholarly journals Effect of Incremental Shrinking Process on Mechanical Properties and Microstructure of Alloy through Electron Backscatter Diffraction Analysis

2021 ◽  
Vol 2083 (2) ◽  
pp. 022079
Author(s):  
Zhengwei Gu ◽  
Yusheng Li ◽  
Ziming Tang ◽  
Ge Yu
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Electron Backscatter Diffraction ◽  
Mechanical Tests ◽  
Mechanical Anisotropy ◽  
Forming Process ◽  
Ebsd Data ◽  
Electron Backscatter ◽  
Shrinking Process ◽  
Backscatter Diffraction

Abstract In recent years, the incremental shrinking process has been widely used in the forming process of aluminum alloy components for the railway vehicles. The effect of the incremental shrinking process on the performance and microstructure of 6082-T6 aluminum alloy was investigated through mechanical tests and electron backscatter diffraction (EBSD) analysis. The tensile test specimens prepared in different rolling orientations (0˚,45˚and 90˚) along the original and deformed sheets exhibited the mechanical anisotropy. After the incremental shrinking process, the average microhardness, tensile strength, and yield strength of this alloy were respectively increased by nearly 8.78%,2.26%,2.72%, while the Elongation was decreased by almost 31.67%. By analyzing the EBSD data, the strength of the material is increased by the incremental shrinking process and its mechanical anisotropy is improved, whereas its plasticity is greatly deteriorated.

Observations of Dislocation Structure in AA 7050 by EBSD

2011 ◽  
Vol 702-703 ◽  
pp. 493-498 ◽  
Author(s):  
C.C. Merriman ◽  
David P. Field
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Dislocation Density ◽  
Cell Walls ◽  
Electron Backscatter Diffraction ◽  
Geometrically Necessary Dislocation ◽  
Dislocation Densities ◽  
Electron Backscatter ◽  
Dislocation Density Tensor ◽  
Backscatter Diffraction

During and after plastic deformation of metals, dislocations tend to evolve into generally well-defined structures that may include tangles, bands, cell walls, and various additional features. Observation of these structures by electron backscatter diffraction is only accomplished by analysis of changes in orientation from one position to the next. Excess (or geometrically necessary) dislocation densities can be inferred from 2D measurements or obtained directly from 3D measurements as indicated by Nye’s dislocation density tensor. Evolution of excess dislocation densities was measured for a split channel die specimen of aluminum alloy 7050 in the T7451 temper. Densities evolved by a factor or 1.6 for compressive deformations of 15%.

A high-fidelity crystal-plasticity finite element methodology for low-cycle fatigue using automatic electron backscatter diffraction scan conversion: Application to hot-rolled cobalt–chromium alloy

2021 ◽  
pp. 146442072110108
Author(s):  
Yuhui Tu ◽  
Seán B Leen ◽  
Noel M Harrison
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Crack Initiation ◽  
Crystal Plasticity ◽  
Electron Backscatter Diffraction ◽  
Voronoi Tessellation ◽  
Fatigue Crack Initiation ◽  
Crystal Plasticity Finite Element ◽  
Electron Backscatter ◽  
Backscatter Diffraction

The common approach to crystal-plasticity finite element modeling for load-bearing prediction of metallic structures involves the simulation of simplified grain morphology and substructure detail. This paper details a methodology for predicting the structure–property effect of as-manufactured microstructure, including true grain morphology and orientation, on cyclic plasticity, and fatigue crack initiation in biomedical-grade CoCr alloy. The methodology generates high-fidelity crystal-plasticity finite element models, by directly converting measured electron backscatter diffraction metal microstructure grain maps into finite element microstructural models, and thus captures essential grain definition for improved microstructure–property analyses. This electron backscatter diffraction-based method for crystal-plasticity finite element model generation is shown to give approximately 10% improved agreement for fatigue life prediction, compared with the more commonly used Voronoi tessellation method. However, the added microstructural detail available in electron backscatter diffraction–crystal-plasticity finite element did not significantly alter the bulk stress–strain response prediction, compared to Voronoi tessellation–crystal-plasticity finite element. The new electron backscatter diffraction-based method within a strain-gradient crystal-plasticity finite element model is also applied to predict measured grain size effects for cyclic plasticity and fatigue crack initiation, and shows the concentration of geometrically necessary dislocations around true grain boundaries, with smaller grain samples exhibiting higher overall geometrically necessary dislocations concentrations. In addition, minimum model sizes for Voronoi tessellation–crystal-plasticity finite element and electron backscatter diffraction–crystal-plasticity finite element models are proposed for cyclic hysteresis and fatigue crack initiation prediction.

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