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NEW EROSION RESISTANCE MATERIALS FOR HYDRO POWER INDUSTRY
Published in C.V.J. Varma, B.S.K. Naidu, A.R.G. Rao, Silting Problems in Hydro Power Plants, 2020
MUKESH K. SHARMA, M.K. DAS, D. SHIVANI
Al-bronze filler metals for use with gas shielded TIG and MIG welding process are readily available commercially for Al-bronze alloys. Generally, the filler metals should match the composition of the material being welded. Post weld heat treatment to relieve stresses is recommended for the most critical applications [].
Metal Joining Techniques Using Brazing
Published in Yoseph Bar-Cohen, Advances in Manufacturing and Processing of Materials and Structures, 2018
Yoseph Bar-Cohen, Dusan P. Sekulic, Rui Pan, Sudarsanam Suresh Babu, Anming Hu, Denzel Bridges, Xiaoqi Bao, Mircea Badescu, Hyeong Jae Lee, Stewart Sherrit
Varieties of alloys are used as brazing filler metals (BFMs) depending on the process that is applied, the material systems to be brazed, and the application of the specific structure that is being brazed. Brazing alloys are mostly made of two or more metals (although single-component brazes, especially using precious metals, have a number of specialized applications) that form an alloy with the desired properties. The braze metals are chosen based on their ability to wet the base metals, sustain the service conditions, and melt at a lower temperature than the base metals or at a very specific temperature. In the case of induction brazing, the filler is usually placed beforehand and the process is executed automatically. Some of the more common types of filler metals are aluminum-silicon, or amorphous-brazing foils using nickel, copper, copper-silver, copper-zinc (brass), gold-silver, nickel alloy, silver, etc.
Effect of different interlayers on microstructure and mechanical properties of diffusion-bonded joints between SiC and 316LN
Published in Philosophical Magazine, 2022
Bensheng Huang, Zhihang Shu, Tianning Li, Hao Li, Dongyu Zhang, Feng Yi
However, there are chemical (mainly strong reactivity) and thermomechanical incompatibility between ceramics and metals at high temperatures. It is difficult to achieve a strong joint between the two using traditional welding methods [5]. Residual stress still exists in the joint owing to the large difference in the coefficient of thermal expansion (CTE) between ceramics and metals [6]. In recent years, to overcome the issue of forming an efficient joint between ceramics and metals, many reliable joining technologies such as solid-phase diffusion bonding [7,8], active metal brazing [9,10] and activated molybdenum-manganese (Mo-Mn) methods [11,12] have been developed. However, indirect brazing processes such as the activated Mo-Mn method are cumbersome, and the strength of the joint is limited by the adhesion of the metallisation layer and cannot reach a high level. On this basis, the improved active metal brazing uses a lower melting point of the brazing filler metal, so the working temperature of the joint is lower. However, it limits the industrial application of the joint. Even if high-temperature active solder is used, it is difficult to obtain an efficient joint under very high temperatures [13]. Solid-phase diffusion bonding can minimise cracks, relieve thermal stress, and have better high-temperature properties through the complete interdiffusion of interfacial atoms under pressure. Therefore, welded components made of heterogeneous metals and ceramic/metal heterogeneous materials have a wide range of high-temperature applications in aerospace and nuclear fields [14–16].
Investigation on thermo-mechanical performances of friction stir welding of aluminum alloys (AA6063)
Published in Welding International, 2022
Jogendra Kumar, Prasenjit Patra, Arpan Kumar Mondal, Rajesh Kumar Verma
In industries, welding is mainly used as a joining process in which two materials are welded at desired surfaces using an appropriate heat and pressure application [1,2]. The process was invented throughout the bronze and iron eras in ancient times, i.e. forge welding. With the discovery of acetylene in the 18th century, electric revolutionized the entire process. The 19th century was a golden age for welding prevalent due to industrialization and urbanization. In this century, various welding techniques have been invented: the resistance welding process, electro slag welding, Plasma arc welding (PAW), Submerged-arc welding (SAW), Tungsten Inert Gas (TIG) welding, and underwater welding. In 1991, one new type of welding process was founded by The Welding Institute (TWI) called friction stir welding, i.e. solid-state joining process. Various industries have used it because of its versatility in demanding sectors, such as automobile, marine, and aerospace components. Large-diameter solder generated the required heat to soften the metal in the FSW process with a rotating tool. After that, it pressed the metal to form a permanent joint. Once the tool pin has penetrated, and the shoulder has contacted the parent material, some dwell time is required before moving the tool along the meeting line of the two base plates [3,4]. The temperature during welding does not rise to the melting temperature; usually, the highest temperature lies in the range of 0.6 to 0.9 times the melting temperature of the base metal [3,5]. FSW is one of the most eco-friendly processes (no shielding gas or flux is used) in modern manufacturing because of its friendliness, energy efficiency, and versatility [6]. It is challenging to perform fusion welding without filler metal [7,8]. Friction stir welding can be used to make a variety of joints, including lap joints, butt joints, T-joints, fillet joints, and butt joints in various materials, including Al-alloys, Mg-alloys, Cu-alloys, and steels components [5,9–22]. There has been an increasing demand for a lightweight material that has good weldability and formability for the aircraft and automobile industries in recent years. Aluminum alloys have all these qualities that can be used in the manufacturing industries. Under static and dynamic loading, it has a high strength-to-weight ratio, corrosion resistivity, and elastic behavior. The conventional arc welding process makes it challenging to weld due to its lower melting temperature. Many welding defects like blow holes, large porosity heat-affected zone (HAZ), and solidification cracking reduce the welding strength [23]. The electric resistance has very low compared to the ferrous metals; therefore, resistance welding is not suitable for aluminum. TIG is ideal for thin plates up to 3 mm, and shielding gas is necessary. An experienced welder needs to produce good quality joints, and another issue due to excessive heat is there, like residual stress HAZ, etc. Thus, the solid-state welding process FSW is used to avoid flaws, such as porosity in Al-alloy weldments which is usually observed in fusion welding of these alloys [24–26]. As the temperature does not rise to the melting point of the base metal in FSW, substantial porosity formation is not likely, and a narrower HAZ is formed [27].