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Vacuum Materials, Hardware, Fabrication Techniques, Cleaning Processes and Surface Treatment
Published in Pramod K. Naik, Vacuum, 2018
to provide a protective envelope around the weld area to avoid oxidation. Argon and helium are generally preferred. Types of fusion welding include Oxyacetylene cutting/welding Shielded metal arc Metal inert gas (MIG) Tungsten inert gas (TIG)
Porosity in Welds
Published in German Deyev, Dmitriy Deyev, Surface Phenomena in Fusion Welding Processes, 2005
Pores are the most common defects in welds made by different fusion welding methods. Therefore, the majority of researchers involved in welding or surfacing technologies studied the process of formation of pores in the welds to different extents. Experimental and theoretical information on this process, accumulated up to now, is very extensive.
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
For joining metals and alloys, welding, brazing, and soldering are the most common methods. Fusion welding consists of melting a part of the metal at the joint interface and allowing the joint to form by flow of the liquid metal, usually with another filler metal. When the same process is assisted by compressive forces applied by clamping the two pieces, the process is called pressure welding. Brazing and soldering use a lower-melting filler metal alloy to join the components. The parent pieces do not undergo melting and the liquid filler acts as the glue that makes the joint. The heat required to cause melting in the welding process classifies the process. Thus, in arc welding, heat is provided by creating an electric arc between electrodes often in the presence of a shielding atmosphere. Gas welding is performed using a gas mixture fuel to create a high-temperature flame that is targeted at the joining interface. The most popular gas-welding device is the oxyacetylene welding torch commonly seen in metalworking shops. Thermite welding is a well-known process for joining large sections in remote locations where gas or electric welding are difficult to perform. The thermite process relies on the exothermic heat generated by the reaction of iron oxide with aluminum. The molten product of the exothermic reaction is brought in contact with the joining interface and causes local melting of the parent pieces, followed by cooling, to form the weld. Electron and laser beam welding are some of the modern methods for joining metals and ceramics. Other methods include electroslag welding, friction welding, and explosive welding, which are made possible by a transient wave generated by detonating an explosive charge.
Effect of Welding Speed and Post-Weld Heat Treatment on Microstructural and Mechanical Properties of Alpha+Beta Titanium Alloy EB Welds
Published in Fusion Science and Technology, 2023
Vamsi Krishna K, Gopi Krishna C, Ateekh Ur Rehman, Kishore Babu Nagumothu, Mahesh Kumar Talari, Prakash Srirangam
Various fusion welding techniques, including friction welding (FW), plasma arc welding, electron beam welding (EBW), gas tungsten arc welding (GTAW), friction stir processing, laser beam welding (LBW), and gas metal arc welding, are utilized in different sectors to produce structural components. However, in the joining process of titanium alloys, due to their high affinity to gaseous elements such as O, hydrogen (H), and N at temperatures above 500°C, embrittlement may occur, which could reduce the ductility of the weld and corrosion resistance. Thus, the welding of these alloys must be done in an inert atmosphere or vacuum. EBW, therefore, is suitable for the welding of titanium alloys, as it can produce clean and high-quality welds, as the complete component is sealed in a vacuum environment, inherently providing better protection from the environment.[7–9] Furthermore, the high-energy beam power source in EBW produces single-pass full-penetration welds for thicker sections, which are difficult to achieve in conventional welding techniques. Additionally, deep penetration and narrower welds with a lower width of the heat-affected zones (HAZs) due to low heat input can be obtained, resulting in lower residual stresses and workpiece distortion.[10,11]
A review on weldability and corrosion behaviour of L-PBF printed AlSi10Mg alloy
Published in Canadian Metallurgical Quarterly, 2023
Navdeep Minhas, Varun Sharma, Shailendra Singh Bhadauria
Three types of joint configurations viz. butt joint, lap joint, and T-joint were taken under study. The results revealed that for the laser beam welded butt joint, the fatigue strength of the stress amplitude at the knee point varied from 15.8 to 28.0 MPa for long to short welds. It was further reducing the fatigue strength for other joint configurations. The failure points were noted and suggested that they occurred due to porosity because the LBW is highly susceptible to the porosity occurrence in the upper weld metal zone. Moreover, pores act as stress concentrations for crack initiation during fatigue loading. However, fusion welding processes pose porosity defects in the weldments. The aluminium alloys are considered to be hard to weld materials, due to their low melting point. The joining of AM AlSi10Mg as a stationary part with conventional AA6060-T6 as a flyer part using a Magnetic pulse welding process (solid-state welding) was proposed as a non-conventional welding process [157]. Successful weld seam consists of a wavy structure, and ‘pockets’ were reported off alloy's re-melted zone. An increase in the hardness of the weld seam with the sound leak-proof weld was reported through the experimental study.
Formation of functionally graded hybrid composite materials with Al2O3 and RHA reinforcements using friction stir process
Published in Australian Journal of Mechanical Engineering, 2022
Chandra Vikram Singh, Praveen Pachauri, Shashi Prakash Dwivedi, Satpal Sharma, R. M. Singari
Friction Stir Welding (FSW) is a solid-phase welding method which permits welding of a wide range of parts and geometries. This method was developed by The Welding Institute (TWI) in 1991 (Cavaliere et al. 2006). This method finds its potential applications in aerospace, automobile, shipbuilding, and many other manufacturing industries (Cavalierea, Squillace, and Panellaa 2008). The FSW process is valuable for welding of aluminium alloys, as the fusion welding has its limitations for these alloys. It is comparatively a simple and fast process. This process is not only fast and efficient but also environmental friendly (Mishraa and Ma 2005). It can be used to join two dissimilar materials and is capable of providing welds without defects as compared to fusion welding processes (Liu et al. 2005). The development of composite materials via friction stir process is one of the interesting research areas these days, due to its various advantages over the conventional casting process. Mechanical properties of the metal are not degraded after friction stir process (Kumbhar and Bhanumurthy 2008). During this process, there is no production of fumes and unwanted metal spatter of molten state. Further, no consumable, no filler metal and no shielding gas is required in this process. Friction stir process is a ‘green’ technology as it does not produces any health hazardous materials which may lead to the destruction of the environment or people. Additionally, there is no requirement to clean the metal surface (Ahmadi, Toroghinejad, and Najafizadeh 2014).