Download Free Mechanism Of Variation In High Temperature Grain Stability Of Aluminum In Dissimilar Friction Stir Welds Book in PDF and EPUB Free Download. You can read online Mechanism Of Variation In High Temperature Grain Stability Of Aluminum In Dissimilar Friction Stir Welds and write the review.

In the dissimilar Friction Stir Welding (FSW) of aluminum to titanium, a large fraction of titanium particles is inhomogeneously distributed in the weld nugget and their distribution is highly complex. Such a distribution can have an immense influence on the grain stability of the weld nugget, which decides its mechanical properties at the high temperatures experienced in critical applications. The present investigation highlights the variation in grain structure at the top surface and center of the weld nugget. The results show that the microstructure at the surface of the weld contains a higher fraction of fine titanium particles, refined grains of aluminum and high-angle grain boundaries, and a lower intensity of shear texture components when compared to the center of the weld nugget. The variation in the grain stability of the weld was correlated with the qualitative variation in the strain rate and temperature in the weld. It is proposed that the formation and distribution of a high fraction of fine titanium particles results in superior grain stability of aluminum at the surface of the weld due to arrest of the grain boundary mobility against grain growth. This mechanism and methodology can be applied in developing metal matrix composites with superior mechanical properties as well.
This collection presents fundamentals and the current status of friction stir welding (FSW) and solid-state friction stir processing of materials and provides researchers and engineers with an opportunity to review the current status of the friction stir related processes and discuss the future possibilities. Contributions cover various aspects of friction stir welding and processing including their derivative technologies. Topics include, but are not limited to: • Derivative technologies • High-temperature applications • Industrial applications • Dissimilar alloys and/or materials • Lightweight alloys • Simulation • Characterization • Non-destructive examination techniques
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.
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
The text focuses on discussing the solid-state deformation behavior of materials in additive manufacturing processes. It highlights the process optimization and bonding of different layers during layer-by-layer deposition of different materials in Solid-State. It covers the design, process, and advancement of solid-state additive manufacturing methods. Covers the fundamentals of materials processing, including the stress–strain–temperature correlation in solid-state processing and manufacturing Discusses solid-state additive manufacturing methods, and optimization strategies for the fabrication of additive manufacturing products Showcases the mechanisms associated with improvement in mechanical properties of Solid-State additive manufacturing products Provides a comprehensive discussion on microstructural stability and homogeneity in mechanical properties Presents hybrid solid-state process for fabrication of multilayer components and composite materials Provides a detailed review of laser-based post-processing techniques The text focuses on the Solid-State additive manufacturing techniques for the fabrication of industrially relevant products. It gives in-depth information on the fundamental aspects, hybridization of the processes, fabrication of different materials, improvement in product performance, and Internet of Things enabled manufacturing. The text covers crucial topics, including hybrid Solid-State additive manufacturing, cold spray additive manufacturing, online defect detection of products, and post-processing of additively manufactured components. These subjects are significant in advancing additive manufacturing technology and ensuring the quality and efficiency of the produced components. It will serve as an ideal reference text for senior undergraduate and graduate students, and researchers in fields such as mechanical engineering, aerospace engineering, manufacturing engineering, and production engineering.
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.
Friction stir welding (FSW) is a highly important and recently developed joining technology that produces a solid phase bond. It uses a rotating tool to generate frictional heat that causes material of the components to be welded to soften without reaching the melting point and allows the tool to move along the weld line. Plasticized material is transferred from the leading edge to trailing edge of the tool probe, leaving a solid phase bond between the two parts. Friction stir welding: from basics to applications reviews the fundamentals of the process and how it is used in industrial applications.Part one discusses general issues with chapters on topics such as basic process overview, material deformation and joint formation in friction stir welding, inspection and quality control and friction stir welding equipment requirements and machinery descriptions as well as industrial applications of friction stir welding. A chapter giving an outlook on the future of friction stir welding is included in Part one. Part two reviews the variables in friction stir welding including residual stresses in friction stir welding, effects and defects of friction stir welds, modelling thermal properties in friction stir welding and metallurgy and weld performance.With its distinguished editors and international team of contributors, Friction stir welding: from basics to applications is a standard reference for mechanical, welding and materials engineers in the aerospace, automotive, railway, shipbuilding, nuclear and other metal fabrication industries, particularly those that use aluminium alloys. Provides essential information on topics such as basic process overview, materials deformation and joint formation in friction stir welding Inspection and quality control and friction stir welding equipment requirements are discussed as well as industrial applications of friction stir welding Reviews the variables involved in friction stir welding including residual stresses, effects and defects of friction stir welds, modelling thermal properties, metallurgy and weld performance
Local melting and tool slippage during friction stir spot welding of different aluminum alloys is examined using a combination of detailed microscopy and temperature measurement. It has been widely accepted that friction stir welding is a solid-state process and does not involve melting. The present research indicates that local melting is an inherent feature when Al 7075 and Al 2024 alloys are spot welded, and produces tool slippage at the tool contact interface. In contrast, intermetallic particles contained in the Al 5754 and Al 6061 as-received materials do not melt and a no-slip condition is maintained. A combination of data acquisition of key welding parameters (axial force, torque and tool displacement), high-speed imaging, temperature measurement and metallography are employed to study the tool penetration stage and the subsequent dwell period during spot welding. A methodology is developed for reliably determining the stir zone temperature using thermocouples embedded within the tool itself. Tool slippage is investigated by determining the strain rate in stir zone material adjacent to the rotating tool. The strain rate is estimated by substituting stir zone temperature and subgrain size measurements into the Zener-Hollomon equation. Tool penetration early in the friction stir spot welding process can be explained as a progression of wear events from mild (delamination) wear, through to severe wear, and finally to melt wear in the material located immediately under the tip of the rotating pin. The stir zone peak temperature during welding is limited by either the solidus temperature of the alloy in question, or by local melting of intermetallic particles contained in the base material such as Al 7075 or Al 2024 alloys. Melted films dissolve rapidly in the high temperature stir zone, and as the weld cools to room temperature. Metallographic evidence confirming local melting and cracking is observed in Al 7075 and Al 2024 alloy friction stir spot welds made using a combination of rapid quenching, a high plunge rate and an extremely short dwell time setting. When slower plunge rates and longer dwell times are applied the dissolution of the melted films removes evidence of their occurrence.
This chapter investigates on the characterization of friction stir welded dissimilar aluminium alloys AA2024 with AA5052, AA2024 with AA6061 and AA 5052 with AA6061. Five tool designs were employed with first two dissimilar combinations to analyze the influence of rotation and traverse speed over microstructural and mechanical properties. H13 tool steel was used as tool material with various pin profiles which includes cylindrical, cylindrical-threaded, squared, tapered and stepped types. In the dissimilar welding of AA 2024 with AA 5052, sound welds were produced with stepped pin tool. In the dissimilar welding of AA 2024 with AA 6061, ratio between tool shoulder to diameter of tool pin was the most influential factor. Welded joints failed in the Heat affected zone (HAZ) of 6061 where the hardness values were comparatively less. In dissimilar welding of AA 5052 with AA6061, cylindrical pin tool was used at a constant speed of 710 rpm and at different feed rates of 28 and 40 mm/minutes Micro structural examination showed variation of grain size in every zone and their influence on mechanical properties. Correlating mechanical and metallurgical properties, the optimized process parameters of speed and feed were identified to be 710 rpm and 28 mm/min respectively for all attempted dissimilar combinations.
Friction stir welding (FSW) is a solid state joining process 1,2,3 that uses a rapidly-rotating, non-consumable high strength tool-steel pin that extends from a cylindrical shoulder (Figure 1). The workpieces to be joined are firmly clamped to a worktable; the rotating pin is forced with a pre-determined load into them and moved along the desired bond line. Frictional heating is produced from the rubbing of the rotating shoulder with the workpieces, while the rotating pin deforms (i.e. 'stirs') the locally-heated material. To produce a high integrity defect-free weld, process variables (RPM of the shoulder-pin assembly, traverse speed, the downward forging force) and tool pin design must be chosen carefully. FSW can be considered as a hot-working process in which a large amount of deformation is imparted to the workpiece through the rotating pin and the shoulder. Such deformation gives rise to a weld nugget (whose extent is comparable to the diameter of the pin), a thermomechanically-affected region (TMAZ) and a heat-affected zone (HAZ). Frequently, the weld nugget appears to comprise equiaxed, fine, dynamically recrystallized grains whose size is substantially less than that in the parent material. The objective of the present research was to develop a basic understanding of the evolution of microstructure in the dynamically recrystallized region and to relate it to the deformation process variables of strain, strain rate, and temperature. Such a correlation has not been attempted before perhaps because of the difficulty in quantifying the process variables. To overcome such difficulties, recent work 4 to measure and model the local temperature transients during FSW was utilized, and an approximate method was employed to estimate the strain and strain rate in the weld nugget.