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Contemporary Machining Processes for New Materials
Published in E. S. Gevorkyan, M. Rucki, V. P. Nerubatskyi, W. Żurowski, Z. Siemiątkowski, D. Morozow, A. G. Kharatyan, Remanufacturing and Advanced Machining Processes for New Materials and Components, 2022
E. S. Gevorkyan, M. Rucki, V. P. Nerubatskyi, W. Żurowski, Z. Siemiątkowski, D. Morozow, A. G. Kharatyan
In the plasma arc welding (PAW) process, the arc can pass through a nozzle which constricts the arc reducing its cross-sectional area. As a result of increased energy density and velocity of the plasma, the temperature dramatically increases to ca. 25,000°C. Plasma arc welding uses nonconsumable tungsten electrodes and shielding gas (Sahoo and Tripathy, 2021). According to the process current, three types of plasma arc welding processes can be distinguished: Micro-plasma arc welding with a forming current below 15 A. It produces low energy density and low plasma velocity and thus is suitable for thin sheet processing. Melt-in mode plasma arc welding, where current varies between 15 and 400 A. It is usually applied to the welding of thicker, up to 2.4 mm sheets.Keyhole mode plasma arc welding is used for 2.5-mm thick materials. The plasma-forming current works at more than 400 A.
Joining Technologies
Published in Raghu Echempati, Primer on Automotive Lightweighting Technologies, 2021
Arc welding is categorized by the type of electrode, consumable or nonconsumable. For aluminum, metal inert gas (MIG) welding (also referred to as gas metal arc welding), tungsten inert gas (TIG) welding (often referred to as gas tungsten arc welding), and plasma arc welding (PAW) are the most common. MIG welding is a semiautomatic or automatic welding process where a continuously fed consumable wire acts as both the filler material and the electrode (Figure 6.1). The welding wire uncoils automatically from a reel to the welding torch. Heat is produced by an arc between the electrode and the base material. MIG welding is a versatile welding process that is suitable for practically all metals, easy to perform on a wide variety of materials (heavy or light gauge), and requires little to no post-welding finishing processes. Differentiation can be made between MIG welding and metal active gas (MAG) welding. For steel welding, active gas mixtures (mainly argon-based gas mixtures which contain oxygen or carbon dioxide) are preferred. In contrast, for aluminum and most other metals, inert shielding gases (argon, helium, or mixtures of these two) are exclusively utilized.
Introduction
Published in P. Chakravarthy, M. Agilan, N. Neethu, Flux Bounded Tungsten Inert Gas Welding Process, 2019
P. Chakravarthy, M. Agilan, N. Neethu
The welding arc is a high-current and low-voltage electrical discharge which flows from the cathode to the anode. The flow of current through the gap between the electrode and the workpiece needs a column of charged particles to have reasonably good electrical conductivity. The electric discharge is sustained through a path of ionized gaseous particles called plasma. Various mechanisms such as field emission, thermal emission, secondary emission etc. cause the generation of these particles. The temperature inside the arc and at the surface of the arc is approximately 15,000°C and 10,000°C, respectively. The open-circuit voltage for a typical arc welding process ranges from 30 to 80 volts, and typical currents are between 50 and 300 A. The energy developed in the arc per unit time equals V × I, where V is the arc voltage and I the current. The welding arc acquires the shape of hot gas formed between the electrodes, and due to its low density, hot gas tends to rise and form a bell-shaped arc. Further, fusion welding processes are categorized based on the type of electrode used. Consumable electrode processes – shielded metal arc welding (SMAW), submerged arc welding (SAW), flux cored arc welding (FCAW), gas metal arc welding (GMAW) and electroslag welding (ESW) processes. Non-consumable electrode processes – gas tungsten arc welding and plasma arc welding processes.
Optimization of the weld characteristics of plasma-arc welded titanium alloy joints: an experimental study
Published in Materials and Manufacturing Processes, 2022
T Pragatheswaran, S. Rajakumar, V. Balasubramanian
Titanium welds by gas tungsten arc welding are performed with filler additions (sometimes activated flux) to achieve proper penetration and current pulsation to achieve lower heat input and grain refinement.[10–12] The arc produced during Plasma arc welding is denser and stiffer and able to provide arc constriction results in narrower weld beads and higher penetration at higher welding speeds compared to gas tungsten welding.[13,14] Plasma arc welding characteristics are vitally controlled by its primary parameters, namely current, speed, plasma gas flow rate, and constricted arc length. Each parameter has its effect and combinatorial effect when interacted with each other on the weld characteristics, such as weld bead width, penetration, fusion zone area, and grain formation.
Mechanical properties of plasma arc welded AISI304LN austenitic stainless steel at various temperatures
Published in Canadian Metallurgical Quarterly, 2023
Ramazan Kaçar, Hayriye Ertek Emre, Samet Nohutçu
In industrial applications, austenitic stainless steels can be joined by different arc welding methods. Plasma arc welding stands out compared to other arc welding methods due to its high energy concentration, narrower and deeper penetration, and high arc stability [24]. It has been stated that the width of HAZ is narrower than traditional welding methods (i.e. TIG) due to the high heat density, high welding filler feeding rate and high-power density of the plasma arc welding method [25].