The Effect of Friction Stir Processing on the Microstructure and Mechanical Properties of AF/C458 Aluminum Lithium Alloy PDF Download

Author:
Publisher:
ISBN:
Category : Aluminum alloys
Languages : en
Pages : 73

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Book Description
Aluminum-lithium alloys have been under development for lightweight - high strength aerospace structures but implementation has been slowed significantly because of poor short transverse fracture toughness and brittle intergranular delamination cracking. The alloy AF/C458 (now designated AA 2099) has been designed to exhibit decreased mechanical anisotropy and improved fracture toughness while maintaining ductility and strength levels. This thesis examines the application of Friction Stir Processing (FSP) of AF/C458 as an approach to refine and homogenize the grain structure and enhance mechanical properties. FSP of peak-aged material results in refined, equiaxed grains but with reduced hardness due to the heat input of the process. The effect of post-FSP heat treatment has been established and the influence of FSP on tensile and fatigue properties has been determined.

Author: Nelson Gomes Affonseca (Netto)
Publisher:
ISBN:
Category : Aluminum alloys -- Hardenability
Languages : en
Pages :

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Book Description
Friction Stir Processing (FSP) is a promising thermomechanical technique that is used to modify the microstructure of metals locally, and thereby locally improve mechanical properties of the material. FSP uses a simple and inexpensive tool, and has been shown to eliminate pores and also reduce the sizes of intermetallics in aluminum alloys. This is of great interest for research on solidification, production and performance of aluminum alloy castings because FSP can enhance the structural quality of aluminum casting significantly by minimizing the effect of those structural defects. In the literature, there is evidence that the effectiveness of FSP can change with tool wear of the tool used. Therefore, a study was first conducted to determine the effect of FSP time on the tool life and wear in 6061-T6 extrusions. Results showed the presence of two distinct phases in the tool life and wear. Metallographic analyses confirmed that wear in Phase I was due to fracture of the threads of the tool and Phase II was due to regular wear, mostly without fracture. Moreover, built-up layers of aluminum were observed between threads. The microhardness profile was found to be different from those reported in the literature for 6061-T6, with Vickers hardness increasing continuously from the the stir zone to the base material. To investigate the degree of effectiveness of FSP in improving the structural quality of cast A356 alloys, ingots with different quality (high and low) were friction strir processed with single and multiple passes. Analysis of tensile test results and work hardening characteristics showed that for the high quality ingot, a single pass was sufficient to eliminate the structural defects. Subsequent FSP passes had no effect on the work hardening characteristics. In contrast, tensile results and work hardening characteristics improved with every pass for the low quality ingot, indicating that the effectiveness of FSP was dependent on the initial quality of the metal. The evolution of microstructure, specifically the size and spacing of Silicon (Si) eutectic particles, was investigated after friction stir processing of high quality A356 castings with single and multiple passes. Si particles were found to coarsen with each pass, which was in contrast with previous findings in the literature. The nearest neighbor distance of Si particles also increased with each FSP pass, indicating that microstructure became progressively more homogeneous after each pass. In the literature, the improvement observed after FSP of Al-Si cast alloys was attributed to the refinement of Si particles. Tensile data from high quality A356 ingot showed that there was no correlation between the size of Si particles and ductility. To the author's knowledge, this is the first time that the absence of a correlation between Si particle size and ductility has been found.

Author: Dr. Chandan Deep Singh
Publisher: BookRix
ISBN: 3743849682
Category : Technology & Engineering
Languages : en
Pages : 71

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Book Description
FSP is manufacturing the Technique used to modify the microstructure metals. In this process a rotating tool is penetrated in the work piece and moved in the transverse direction.Further FSP technique is used for fabrication of surface composite on aluminium substrate and homogenization of powder metallurgy aluminium alloy, metal matrix composites, and the cast aluminium alloys. By this process material properties can be improved due to enhancement of grain structure. With this technique the material have shown good corrosion resistance, high strength and high fatigue resistance.

Author: Abby Cisko
Publisher:
ISBN:
Category :
Languages : en
Pages : 226

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Book Description
Technological and design advances in military aircraft have dramatically changed the face of war. The need to rapidly deploy troops, military equipment and technology into conflict areas all over the globe, have placed aircrafts in a pivotal role in strategic battlefield operations. While enhanced aircraft designs now allow significantly heavier loads, greater fuel efficiency and higher speeds, there has been little change in the underlying infrastructure and materials that are used to construct the runways that allow these more sophisticated aircraft to successfully land on a variety of terrains in remote areas of the world. For these reasons, there is a need to improve the strength and weight of temporary aircraft matting used to build temporary runways, landing pads, and other readily usable surfaces for transportation applications. Despite the increasing use of aluminum lithium alloys in aerospace applications because of strength and density, the inability to join higher strength Al alloys with conventional welding techniques made it difficult to use in applications that required welding such as the matting for military runways. Aluminum lithium alloys are currently replacing conventional alloys in the aerospace industry. In comparison to other aluminum alloys, enhanced fatigue crack growth resistance, greater specific strength, high fracture toughness, density reduction, stiffness increase, and superior corrosion resistance can be achieved in Al-Li alloys. The ability to provide lower density with comparable strength gives these alloys an advantage over traditional aluminum alloys. However, conventionally welding these Al-Li alloys is difficult and can materially weaken the resulting product. This disadvantage limits a more widespread implementation of Al-Li alloys. Friction stir welding (FSW) offers the capability to join these high strength aluminum lithium alloys, with environmental, metallurgical, and adaptability advantages over other joining techniques. While FSW has been effectively authenticated and studied for traditional aluminum alloys, there is a necessity for understanding the application of FSW to join AL-Li alloys. The purpose of this research is to examine the microstructural and mechanical performance of AA2099 under static and cyclic loading, as well as the effects of the welding process parameters on the microstructure and mechanical performance of friction stir welded AA2099. This study will aid in the implementation of AA2099 in military applications, specifically for producing high strength, light-weight airfield mats for rapid expansions of airfields.

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: N Eswara Prasad
Publisher: Butterworth-Heinemann
ISBN: 0124016790
Category : Technology & Engineering
Languages : en
Pages : 596

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Book Description
Because lithium is the least dense elemental metal, materials scientists and engineers have been working for decades to develop a commercially viable aluminum-lithium (Al-Li) alloy that would be even lighter and stiffer than other aluminum alloys. The first two generations of Al-Li alloys tended to suffer from several problems, including poor ductility and fracture toughness; unreliable properties, fatigue and fracture resistance; and unreliable corrosion resistance. Now, new third generation Al-Li alloys with significantly reduced lithium content and other improvements are promising a revival for Al-Li applications in modern aircraft and aerospace vehicles. Over the last few years, these newer Al-Li alloys have attracted increasing global interest for widespread applications in the aerospace industry largely because of soaring fuel costs and the development of a new generation of civil and military aircraft. This contributed book, featuring many of the top researchers in the field, is the first up-to-date international reference for Al-Li material research, alloy development, structural design and aerospace systems engineering. Provides a complete treatment of the new generation of low-density AL-Li alloys, including microstructure, mechanical behavoir, processing and applications Covers the history of earlier generation AL-Li alloys, their basic problems, why they were never widely used, and why the new third generation Al-Li alloys could eventually replace not only traditional aluminum alloys but more expensive composite materials Contains two full chapters devoted to applications in the aircraft and aerospace fields, where the lighter, stronger Al-Li alloys mean better performing, more fuel-efficient aircraft

Author: Rajiv S. Mishra
Publisher: ASM International
ISBN: 1615030972
Category : Technology & Engineering
Languages : en
Pages : 360

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Book Description
This book covers the rapidly growing area of friction stir welding. It also addresses the use of the technology for other types of materials processing, including superplastic forming, casting modification, and surface treatments. The book has been prepared to serve as the first general reference on friction stir technology,. Information is provided on tools, machines, process modeling, material flow, microstructural development and properties. Materials addressed include aluminum alloys, titanium alloys, steels, nickel-base alloys, and copper alloys. The chapters have been written by the leading experts in this field, representing leading industrial companies and university and government research insititutions.

Author: Saumyadeep Jana
Publisher:
ISBN:
Category : Aluminum alloys
Languages : en
Pages : 252

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"Al-7Si-0.6Mg is one of the most important cast aluminum alloys because of its attractive mechanical properties and high castability. Microstructurally, the alloy consists of primary aluminum dendrites with eutectic Si particles in the interdendritic region. This makes the alloy quasi-brittle in nature which affects the ductility of the alloy to a great extent. In order to improve the ductility, the eutectic Si particles need to be refined which so far has been achieved by chemical and/or thermal modification. Friction stir processing (FSP) on the other hand can achieve the same through plastic deformation, and therefore replace the cast structure with a wrought microstructure. The eutectic Si particles get refined by at least 50 percent and the aspect ratio also gets reduced. As a result, the FSPed alloy shows improved mechanical properties especially in terms of ductility. Moreover, FSP leads to closure of casting porosities. In the present study it has been observed that these microstructural changes get reflected on the improved fatigue performance by the FSPed alloy. The fatigue life enhances by a factor of five as a result of FSP, when tested using a completely reversed cycle of stress. The life enhancement is even higher at higher stress ratio. Further, FSP caused significant grain refinement inside the stir zone. However, the fine-grain microstructure was found to be unstable at elevated temperatures due to abnormal grain growth (AGG) inside the nugget. Current results indicate that the AGG can be controlled by using selective process parameters as well as run configuration"--Abstract, leaf iv.

Author: Roger Lumley
Publisher: Woodhead Publishing
ISBN: 0081020643
Category : Technology & Engineering
Languages : en
Pages : 594

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Book Description
Fundamentals of Aluminium Metallurgy: Recent Advances updates the very successful book Fundamentals of Aluminium Metallurgy. As the technologies related to casting and forming of aluminum components are rapidly improving, with new technologies generating alternative manufacturing methods that improve competitiveness, this book is a timely resource. Sections provide an overview of recent research breakthroughs, methods and techniques of advanced manufacture, including additive manufacturing and 3D printing, a comprehensive discussion of the status of metalcasting technologies, including sand casting, permanent mold casting, pressure diecastings and investment casting, and recent information on advanced wrought alloy development, including automotive bodysheet materials, amorphous glassy materials, and more. Target readership for the book includes PhD students and academics, the casting industry, and those interested in new industrial opportunities and advanced products. Includes detailed and specific information on the processing of aluminum alloys, including additive manufacturing and advanced casting techniques Written for a broad ranging readership, from academics, to those in the industry who need to know about the latest techniques for working with aluminum Comprehensive, up-to-date coverage, with the most recent advances in the industry

Author: Christopher B. Smith
Publisher: Butterworth-Heinemann
ISBN: 0124201830
Category : Technology & Engineering
Languages : en
Pages : 146

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Book Description
The use of friction stir processing to locally modify the microstructure to enhanced formability has the potential to alter the manufacturing of structural shapes. There is enough research to put together a short monograph detailing the fundamentals and key findings. One example of conventional manufacturing technique for aluminum alloys involves fusion welding of 5XXX series alloys. This can be replaced by friction stir welding, friction stir processing and forming. A major advantage of this switch is the enhanced properties. However qualification of any new process involves a series of tests to prove that material properties of interest in the friction stir welded or processed regions meet or exceed those of the fusion welded region (conventional approach). This book will provide a case study of Al5083 alloy with some additional examples of high strength aluminum alloys. Demonstrates how friction stir processing enabled forming can expand the design space by using thick sheet/plate for applications where pieces are joined because of lack of formability Opens up new method for manufacturing of structural shapes Shows how the process has the potential to lower the cost of a finished structure and enhance the design allowables