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Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys.
Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as brazing and soldering, which do not melt the base metal.
In materials science, fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Once a fatigue crack has initiated, it grows a small amount with each loading cycle, typically producing striations on some parts of the fracture surface. The crack will continue to grow until it reaches a critical size, which occurs when the stress intensity factor of the crack exceeds the fracture toughness of the material, producing rapid propagation and typically complete fracture of the structure.
Friction welding (FWR) is a solid-state welding and bonding process that generates heat through mechanical friction between workpieces in relative motion to one another. This process is used with the addition of a lateral force called "upset" to plastically displace and fuse the materials. Friction welding is a solid-state welding technique similar to forge welding, instead of a fusion welding process. Friction welding is used with metals and thermoplastics in a wide variety of aviation and automotive applications.
Friction stir welding (FSW) is a solid-state joining process that uses a non-consumable tool to join two facing workpieces without melting the workpiece material. Heat is generated by friction between the rotating tool and the workpiece material, which leads to a softened region near the FSW tool. While the tool is traversed along the joint line, it mechanically intermixes the two pieces of metal, and forges the hot and softened metal by the mechanical pressure, which is applied by the tool, much like joining clay, or dough. It is primarily used on wrought or extruded aluminium and particularly for structures which need very high weld strength. FSW is capable of joining aluminium alloys, copper alloys, titanium alloys, mild steel, stainless steel and magnesium alloys. More recently, it was successfully used in welding of polymers. In addition, joining of dissimilar metals, such as aluminium to magnesium alloys, has been recently achieved by FSW. Application of FSW can be found in modern shipbuilding, trains, and aerospace applications.
Shot peening is a cold working process used to produce a compressive residual stress layer and modify the mechanical properties of metals and composites. It entails striking a surface with shot with force sufficient to create plastic deformation.
Surface finishing is a broad range of industrial processes that alter the surface of a manufactured item to achieve a certain property. Finishing processes may be employed to: improve appearance, adhesion or wettability, solderability, corrosion resistance, tarnish resistance, chemical resistance, wear resistance, hardness, modify electrical conductivity, remove burrs and other surface flaws, and control the surface friction. In limited cases some of these techniques can be used to restore original dimensions to salvage or repair an item. An unfinished surface is often called mill finish.
Dr. Ramulu Mamidala is a mechanical engineering professor at University of Washington. Usually goes by the name 'Ram', or 'M.R.', he is recognized for his leadership and outstanding record in promoting collaborative education and research with industry. He is currently the director of Manufacturing Science and Technology Laboratory (MSTL) at Mechanical Engineering Department, University of Washington. He has designed and developed manufacturing methods for a wide range of systems, from the B2 bomber to the Boeing 787. Additionally, in collaboration with industry, he established and directed two interdisciplinary graduate educational programs in engineering and management and a certificate program in composites tooling and manufacturing. His exemplary collaborative efforts motivated working engineers to pursue doctoral studies and he is a leader in using emerging technologies in distance education to reach non-traditional students.
An Almen strip is a thin strip of SAE 1070 steel used to quantify the intensity of a shot peening process.
Laser peening (LP), or laser shock peening (LSP), is a surface engineering process used to impart beneficial residual stresses in materials. The deep, high-magnitude compressive residual stresses induced by laser peening increase the resistance of materials to surface-related failures, such as fatigue, fretting fatigue, and stress corrosion cracking. Laser shock peening can also be used to strengthen thin sections, harden surfaces, shape or straighten parts, break up hard materials, compact powdered metals and for other applications where high-pressure, short duration shock waves offer desirable processing results.
Weld quality assurance is the use of technological methods and actions to test or assure the quality of welds, and secondarily to confirm the presence, location and coverage of welds. In manufacturing, welds are used to join two or more metal surfaces. Because these connections may encounter loads and fatigue during product lifetime, there is a chance they may fail if not created to proper specification.
Low plasticity burnishing (LPB) is a method of metal improvement that provides deep, stable surface compressive residual stresses with little cold work for improved damage tolerance and metal fatigue life extension. Improved fretting fatigue and stress corrosion performance has been documented, even at elevated temperatures where the compression from other metal improvement processes relax. The resulting deep layer of compressive residual stress has also been shown to improve high cycle fatigue (HCF) and low cycle fatigue (LCF) performance.
Friction stir processing (FSP) is a method of changing the properties of a metal through intense, localized plastic deformation. This deformation is produced by forcibly inserting a non-consumable tool into the workpiece, and revolving the tool in a stirring motion as it is pushed laterally through the workpiece. The precursor of this technique, friction stir welding, is used to join multiple pieces of metal without creating the heat affected zone typical of fusion welding.
William John Arbegast, Jr. was an American metallurgical engineer, mechanical engineer and friction stir welding expert.
Ultrasonic impact treatment (UIT) is a metallurgical processing technique, similar to work hardening, in which ultrasonic energy is applied to a metal object. This technique is part of the High Frequency Mechanical Impact (HFMI) processes. Other acronyms are also equivalent: Ultrasonic Needle Peening (UNP), Ultrasonic Peening (UP). Ultrasonic impact treatment can result in controlled residual compressive stress, grain refinement and grain size reduction. Low and high cycle fatigue are enhanced and have been documented to provide increases up to ten times greater than non-UIT specimens.
An Almen round is a thin round disk used to quantify the intensity of a shot peening process. Developed in 1994 by Rudolf Bosshard in Switzerland, it is a modification of the Almen strip method, which is used worldwide as a surface treatment testing method in the field of shot peening. The basic principle is the same, but due to the simple shape and minimized size, the Almen round is more suitable for automated processing and installation on dummy rigs. Also instead of the Almen block according SAE J442, here a matching device is used and if connected to electronic processing unit, the Almen value according AMS-S-13165 can be evaluated in one run.
LSP Technologies, Inc. was located in Dublin, Ohio. The company provided laser peening surface enhancement services and equipment, and other laser technologies.
In metallurgy, peening is the process of working a metal's surface to improve its material properties, usually by mechanical means, such as hammer blows, by blasting with shot, focusing light, or in recent years, with water column impacts and cavitation jets. With the notable exception of laser peening, peening is normally a cold work process tending to expand the surface of the cold metal, thus inducing compressive stresses or relieving tensile stresses already present. It can also encourage strain hardening of the surface metal.
Aluminium alloys are often used due to their high strength-to-weight ratio, corrosion resistance, low cost, high thermal and electrical conductivity. There are a variety of techniques to join aluminium including mechanical fasteners, welding, adhesive bonding, brazing, soldering and friction stir welding (FSW), etc. Various techniques are used based on the cost and strength required for the joint. In addition, process combinations can be performed to provide means for difficult-to-join assemblies and to reduce certain process limitations.
Rotary friction welding (RFW) one of the methods of friction welding, the classic way of which uses the work of friction to create a not separable weld. Typically one welded element is rotated relative to the other and to the forge. The heating of the material is caused by friction work and creates a permanent connection. In this method, the materials to be welded can be the same, dissimilar, or composite and non-metallic materials. The friction welding methods of are often considered as solid-state welding.
References
- ↑ Nachman, G (1999). "Shot Peening - Past, Present and Future, in The 7th International Conference on Shot Peening, Institute of Precision Mechanics" (PDF). www.shotpeener.com. Retrieved 16 January 2024.
- ↑ Stephens, R.I.; Fatemi, A.; Stephens, R.R.; Fuchs, H.O. (2000). Metal Fatigue in Engineering. John Wiley & Sons. ISBN 9780471510598 . Retrieved 2015-07-12.
- ↑ Henry O. Fuchs Student Award http://students.sae.org/awdscholar/awards/fuchs/ Archived 2010-03-06 at the Wayback Machine
- ↑ Curtiss-Wright History http://www.fundinguniverse.com/company-histories/CurtissWright-Corporation-Company-History.html
- ↑ Hackel, Lloyd; Laser Peening Technology Has Come of Age http://www.shotpeener.com/library/pdf/2005028.pdf
- ↑ Effects of Laser Peening, and Shot Peening on Friction Stir Welding https://ntrs.nasa.gov/api/citations/20070001471/downloads/20070001471.pdf
