Process-Structure-Property Relationships in Friction Stir Welded Precipitation Strengthened Aluminum Alloys PDF Download

Author: Barnali Mondal
Publisher:
ISBN:
Category : Aluminum alloys
Languages : en
Pages : 96

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Book Description
Through a series of carefully designed experiments, characterization and some modeling tools, this work is aimed at studying the role of thermal profiles on different microstructural zones and associated properties like strength and corrosion through a variation of weld parameters, thermal boundary conditions and material temper. Two different alloys belonging to the Al-Cu and Al-Cu-Li system in different temper conditions- peak aged (T8) and annealed (O) were used. A 3D-thermal pseudo mechanical (TPM) model is developed for the FSW process using heat transfer module in COMSOL Multiphysics and is based on a heat source wherein the temperature dependent yield shear stress is used for the heat generation. The precipitation and coarsening model is based on the Kampmann and Wagner theoretical framework and accounts for the competition between the various nucleation sites for both metastable and equilibrium precipitates. The model predicts different precipitate mean radius and volume fraction for the various zones in the friction stir welded material. A model for the yield strength is developed which considers contributions from different strengthening mechanisms. The predictions of the each models have been verified against experimental data and literature. At constant advance per rotation, the peak temperature decreases with a decrease in traverse speed and increases with an increase in tool rotation. Weld properties were significantly affected by choice of thermal boundary conditions in terms of backing plate diffusivity. Weld conditions with a higher peak temperature and high strain rate results in more dissolution of precipitates and fragmentation of constituent particles resulting in a better corrosion behavior for the weld nugget. For a peak aged temper of 2XXX alloys, the weld nugget experiences dissolution of strengthening precipitates resulting in a lower strength and the Heat affected zone (HAZ) experiences coarsening of precipitates. For an annealed material, both the weld nugget and HAZ experiences dissolution of precipitates with an increase in strength in the weld nugget.

Author: Alpesh K. Shukla
Publisher:
ISBN: 9780549116226
Category : Materials science and engineering
Languages : en
Pages : 438

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Book Description

Author: Rajiv S. Mishra
Publisher: Butterworth-Heinemann
ISBN: 0128092920
Category : Technology & Engineering
Languages : en
Pages : 112

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Book Description
Friction Stir Processing of 2XXX Aluminum Alloys including Al-Li Alloys is the latest edition in the Friction Stir Welding and Processing series and examines the application of friction stir welding to high strength 2XXX series alloys, exploring the past and current developments in the field. The book features recent research showing significant benefit in terms of joint efficiency and fatigue performance as a result of friction stir welding. Friction stir welding has demonstrated significant benefits in terms of its potential to reduce cost and increase manufacturing efficiency of industrial products including transportation, particularly the aerospace sector. The 2XXX series aluminum alloys are the premium aluminum alloys used in aerospace. The book includes discussion of the potential future directions for further optimization, and is designed for both practicing engineers and materials scientists, as well as researchers in the field. - Provides comprehensive coverage of friction stir welding of 2XXX series alloys - Discusses the physical metallurgy of the alloys - Includes physical metallurgy-based guidelines for obtaining high joint efficiency - Features illustrated examples of the application of FSW in the aerospace industry

Author: Rogie Irwin Rodriguez
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 148

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Book Description
In this work, the relationship between microstructure and mechanical properties of dissimilar friction stir welded AA6061-to-AA7050 aluminum alloys were evaluated. Experimental results from this study revealed that static strength increased with the tool rotational speed and was correlated with the material intermixing. Fully-reversed low cycle fatigue experimental results showed an increase in the strain hardening properties as well as the number of cycles-to-failure as the tool rotational speed was increased. Furthermore, under both static and cyclic loading, fracture of the joint was dominated by the AA6061 alloy side of the weld. In addition, inspection of the fatigue surfaces revealed that cracks initiated from intermetallic particles located near the surface. In order to determine the corrosion resistance of the dissimilar joint, corrosion defects were produced on the crown surface of the weld by static immersion in 3.5% NaCl for various exposure times. Results revealed localized corrosion damage in the thermo-mechanically affected and heat affected zones. Results demonstrated a decrease in the fatigue life, with evidence of crack initiation at the corrosion defects; however, the fatigue life was nearly independent of the exposure time. This can be attributed to total fatigue life dominated by incubation time. Furthermore, two types of failure were observed: fatigue crack initiation in the AA6061 side at high strain amplitudes (>0.3%); and fatigue crack initiation in the AA7050 side at low strain amplitudes (

Author: Rajiv S. Mishra
Publisher: Butterworth-Heinemann
ISBN: 0128094605
Category : Technology & Engineering
Languages : en
Pages : 122

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Book Description
Friction Stir Welding of High Strength 7XXX Aluminum Alloys is the latest edition in the Friction Stir series and summarizes the research and application of friction stir welding to high strength 7XXX series alloys, exploring the past and current developments in the field. Friction stir welding has demonstrated significant benefits in terms of its potential to reduce cost and increase manufacturing efficiency of industrial products in transportation, particularly the aerospace sector. The 7XXX series aluminum alloys are the premium aluminum alloys used in aerospace. These alloys are typically not weldable by fusion techniques and considerable effort has been expended to develop friction stir welding parameters. Research in this area has shown significant benefit in terms of joint efficiency and fatigue performance as a result of friction stir welding. The book summarizes those results and includes discussion of the potential future directions for further optimization. - Offers comprehensive coverage of friction stir welding of 7XXX series alloys - Discusses the physical metallurgy of the alloys - Includes physical metallurgy based guidelines for obtaining high joint efficiency - Summarizes the research and application of friction stir welding to high strength 7XXX series alloys, exploring the past and current developments in the field

Author: Moataz Attallah
Publisher: LAP Lambert Academic Publishing
ISBN: 9783843380690
Category : Aluminum alloys
Languages : en
Pages : 324

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Book Description
Friction Stir Welding (FSW) is known to result in a complex microstructural development, with features that remain unexplained, such as: the formation of the onion rings structure. Moreover, various microstructural factors have been suggested to control the strength in Al-Mg AA5xxx welds, without identifying their relative contribution. Furthermore, the influence of the basemetal microstructural parameters (e.g. grains, intermetallic particles, stored energy) on the microstructure-property development has not been previously investigated. These issues are addressed in the present study.

Author: Harpreet Sidhar
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Rising demand for improved fuel economy and structural efficiency are the key factors for use of aluminum alloys for light weighting in aerospace industries. Precipitation strengthened 2XXX and 7XXX aluminum alloys are the key aluminum alloys used extensively in aerospace industry. Welding and joining is the critical step in manufacturing of integrated structures. Joining of precipitation strengthened aluminum alloys using conventional fusion welding techniques is difficult and rather undesirable in as it produces dendritic microstructure and porosities which can undermine the structural integrity of weldments. Friction stir welding, invented in 1991, is a solid state joining technique inherently benefitted to reduces the possibility of common defects associated with fusion based welding techniques. Weldability of various 2XXX and 7XXX aluminum alloys via friction stir welding was investigated. Microstructural and mechanical property evolution during welding and after post weld heat treatment was studied using experimental techniques such as transmission electron microscopy, differential scanning calorimetry, hardness testing, and tensile testing. Various factors such as peak welding temperature, cooling rate, external cooling methods (thermal management) which affects the strength of the weldment were studied. Post weld heat treatment of AL-Mg-Li alloy produced joint as strong as the parent material. Modified post weld heat treatment in case of welding of Al-Zn-Mg alloy also resulted in near 100% joint efficiency whereas the maximum weld strength achieved in case of welds of Al-Cu-Li alloys was around 80-85% of parent material strength. Low dislocation density and high nucleation barrier for the precipitates was observed to be responsible for relatively low strength recovery in Al-Cu-Li alloys as compared to Al-Mg-Li and Al-Zn-Mg alloys.

Author: Noor Zaman Khan
Publisher: CRC Press
ISBN: 1351642936
Category : Technology & Engineering
Languages : en
Pages : 237

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Book Description
The evolution of mechanical properties and its characterization is important to the weld quality whose further analysis requires mechanical property and microstructure correlation. Present book addresses the basic understanding of the Friction Stir Welding (FSW) process that includes effect of various process parameters on the quality of welded joints. It discusses about various problems related to the welding of dissimilar aluminium alloys including influence of FSW process parameters on the microstructure and mechanical properties of such alloys. As a case study, effect of important process parameters on joint quality of dissimilar aluminium alloys is included.

Author: Peter J. Ditzel
Publisher:
ISBN:
Category :
Languages : en
Pages : 278

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Book Description
Abstract: Friction stir welding is a process with significant potential to eliminate difficulties such as solidification cracking, porosity, and spatter which are often associated with fusion welding of aluminum alloys. Despite the advantages of friction stir welding, local variations in the weld and HAZ microstructure can limit the mechanical properties, introduce defects or present difficulties during welding itself. This work was an investigation into the metallurgical aspects of friction stir welding focusing on microstructure evolution and the relationship between the microstructures developed and weld mechanical properties. Three alloys representative of different alloying systems were used to compare the welding behavior of the various systems. Friction stir welds were produced in 6061 - T6, 5454 - H34, 5454 - 0 and 2195 - T8, followed by microstructural characterization and mechanical testing. Microstructure characterization consisted of optical microscopy and microhardness testing. Mechanical testing included tensile testing and bend ductility testing. The mechanical failures were characterized using optical metallography and SEM and then related to the weld microstructures. Experiments to measure the thermal cycles during welding and the material flow within the stirred region were also performed.

Author: Brandon James Phillips
Publisher:
ISBN:
Category :
Languages : en
Pages : 262

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Book Description
Additive manufacturing is a rapidly growing industry with numerous technologies to suit a variety of applications. However, each application has its own inherent flaws and niches. Aluminum alloys are difficult for the more popular fusion-based additive manufacturing techniques due to the intense thermal gradients generating distortion and selective vaporization of alloying elements. To subjugate some of the issues, the solid-state Additive Friction Stir-Deposition (AFS-D) method was proposed to produce high quality, defect free aluminum deposits. This work investigates the process-structure-property relationships of two popular commercial aluminum alloys employed extensively by consumer, transportation, and defense industries. The first work on process-deformation characteristics of AA6061 were evaluated by producing microhardness profiles taken from the cross-section of builds to produce relationships between mechanical characteristics and machine parameters. Resulting average hardness values were plotted against the processing window and used to determine comparative samples for microstructural analysis. Electron backscatter diffraction and transmission electron microscopy was conducted to characterize the microstructural evolution of depositions. This study provides a succinct, multiscale characterization of as-deposited AFS-D AA6061 to expound the effect of the high-shear solid-state AM process. The subsequent investigation on AA6061 is the first investigation of the process-structure-property relationships of AFS-D in an overlapping, parallel raster deposit. In particular, the deposit produced in this work explores the influence of severe plastic deformation on the as-deposited microstructure and tensile response of material that overlaps in parallel layers at the outer edge of the tool. This study sought to determine the viability of producing large scale structural components larger than the track-width of the AFS-D tool. The final study quantifies the microstructural evolution and consequential tensile response of AA5083. A brief examination of the effect of AFS-D processing parameters was undertaken to determine preferential processing conditions for a larger, free-standing AA5083 structure. Optical and scanning electron microscopy evaluate the microstructural evolution of particles and grain morphology. Tensile properties were evaluated in the longitudinal and vertical build directions, and subsequent fractography discovered the influence of lubrication on the variable mechanical response.