Wire Arc Additive Manufacturing of Ni-based Hastelloy C276 Alloy and Ameliorated Processes

Hastelloy C276 alloy, a typical Ni-based solid solution strengthened trademark superalloy, possesses excellent practical performance under severe environmental conditions and elevated temperatures. Hence, Hastelloy C276 has been investigated as a candidate for structural material for nuclear reactors, chemical processing and aerospace, particularly as aero-engine components. Wire arc additive manufacturing (WAAM), with its relatively high deposition efficiencies and cost-effectiveness, is revolutionising the 3D fabrication of advanced alloy components. However, the effectiveness of WAAM, for fabricating Ni-based alloys, is not fully understood. This thesis explores Hastelloy C276 structures deposited by the WAAM process, aiming to provide an insightful understanding of this process in the fabrication of Hastelloy C276 alloy and to assess and optimise different processing approaches, permitting a systematical investigation of process-microstructure-property interrelationships in WAAM fabricated Hastelloy C276

Additive Manufacturing of Metals

This book is an exciting collection of research articles that offer a unique view into the fast developing field of metal additive manufacturing, providing insights into this advanced manufacturing technology. The articles span recent advances in metal AM technologies, and their application to a wide range of metals, exploring how the processing parameters offer unique material properties. This book encapsulates the state of the art in this rapidly evolving field of technology and will be a valuable resource for researchers in the field, from Ph.D. students to professors, and through to industrial end users

Research reports: 1990 NASA/ASEE Summer Faculty Fellowship Program

A collection of technical reports on research conducted by the participants in this program is presented. The topics covered include: human-computer interface software, multimode fiber optic communication links, electrochemical impedance spectroscopy, rocket-triggered lightning, robotics, a flammability study of thin polymeric film materials, a vortex shedding flowmeter, modeling of flow systems, monomethyl hydrazine vapor detection, a rocket noise filter system using digital filters, computer programs, lower body negative pressure, closed ecological systems, and others. Several reports with respect to space shuttle orbiters are presented

Wire Arc Additive Manufacturing for Stainless Steel-Nickel Superalloy Bimetallic Components

Nickel superalloys have commonly been used in the aerospace, maritime platform, and nuclear industry; because of their high mechanical performance, high thermal creep strength, high corrosion resistance and oxidation resistance, it is one of the best choices for severe environments such as high temperature, high pressure, and corrosive environment. However, due to its high fabrication cost, it is unnecessary to build all the workpieces up with nickel alloys; an appropriate method for manufacturing dual-layer structure with nickel superalloys and body materials has great potential for reducing the material cost without compromising the overall performance. In addition, the high mechanical properties give nickel alloys an edge in industrial production. However, it also limits the manufacturing process of nickel alloys as well—the high strength makes the conventional “subtraction” manufacturing process a difficult task, especially for joining dissimilar materials that require a more accurate shape of the part. Additive manufacturing (AM) processes can build a workpiece with complex geometry. With several AM processes evaluated, the Wire arc additive manufacturing (WAAM) process is considered the best choice for manufacturing these high-strength alloys joined with dissimilar materials for producing quality bimetallic parts

Design and optimization of a protection device for laser weld beads of metal alloys for aerospace applications

2011 - 2012In the present thesis an automated laser welding apparatus was designed and developed in order to perform laser , that allows to achieve laser welding in a controlled, versatile, efficient, reliable, simple, and economical way. This system allows to shield not controlled from oxidation and nitriding process, both the melted pool and the material portion just after welding when the oxidation or nitriding critical temperatures, generally between 200 °C and 500 °C are still in place. Oxidation is even more serious when welding titanium, nickel superalloy, zirconium, molybdenum, stainless steel and other gas-reactive metals and alloys. Most of these materials are used for a wide range of applications in aerospace and biomedical fields as well as for piping in petrochemical, food, semiconductor, nuclear, and chemical industries. These metals can be used in contact with corrosive or sensitive materials without contaminating them, thus making them the number one choices for applications requiring long service life and non-contamination. The resulting oxidized surfaces are not longer corrosion resistant and further treatment may be necessary. Removing the oxidation using mechanical means, such as grinding, also removes the metal’s passive protective layer. The automated laser welding apparatus (patent number: SA2012A000016) was tested with three different joints: butt welding of 3 mm thick Ti6Al4V plates; dissimilar butt welding of 1.5 mm thick of Haynes 188 and Inconel 718 and edge joint of 0.7 mm thick Inconel 625 sheets. All of the tests were performed with automated laser welding apparatus; the bead quality was discussed in terms of geometrical features, porosity content, microstructure, hardness and strength. This work is divided in three parts. In the first part, the principles of operation and the different types of laser are discussed, with mention to the advantages of a disk laser source, which is employed in the experimental part. Also, the types of laser welding, the influence of process parameters and the advantages compared to traditional welding techniques are explained. The second part presents the issue of oxidation caused by welding and the relative solutions proposed in the literature for shielding the bead. Then, the development and the implementation of the automated laser welding apparatus with its components is described. Finally, the capabilities of the automated laser welding apparatus on three different types of joint are discussed in the last part and the relative results are provided. [edited by author]XI n.s

Powder-based laser hybrid additive manufacturing of metals:a review

Recent advances in additive manufacturing (AM) have attracted significant industrial interest. Initially, AM was mainly associated with the fabrication of prototypes, but the AM advances together with the broadening range of available materials, especially for producing metallic parts, have broaden the application areas and now the technology can be used for manufacturing functional parts, too. Especially, the AM technologies enable the creation of complex and topologically optimised geometries with internal cavities that were impossible to produce with traditional manufacturing processes. However, the tight geometrical tolerances along with the strict surface integrity requirements in aerospace, biomedical and automotive industries are not achievable in most cases with standalone AM technologies. Therefore, AM parts need extensive post-processing to ensure that their surface and dimensional requirements together with their respective mechanical properties are met. In this context, it is not surprising that the integration of AM with post-processing technologies into single and multi set-up processing solutions, commonly referred to as hybrid AM, has emerged as a very attractive proposition for industry while attracting a significant R&D interest. This paper reviews the current research and technology advances associated with the hybrid AM solutions. The special focus is on hybrid AM solutions that combine the capabilities of laser-based AM for processing powders with the necessary post-process technologies for producing metal parts with required accuracy, surface integrity and material properties. Commercially available hybrid AM systems that integrate laser-based AM with post-processing technologies are also reviewed together with their key application areas. Finally, the main challenges and open issues in broadening the industrial use of hybrid AM solutions are discussed. 2021, The Author(s).The authors would acknowledge the support received from the ESIF/ERDF Smart Factory Hub (SmartFub) programme in West Midlands. The authors also acknowledge the support received from Yamazaki Mazak, DMG MORI, LASEA and Systems 3R for establishing the hybrid AM facilities at the University of Birmingham.Scopu

Thermal Sprayed Coatings Used Against Corrosion and Corrosive Wear

International audienceCoatings have historically been developed to provide protection against corrosion and erosion that is to protect the material from chemical and physical interaction with its environment. Corrosion and wear problems are still of great relevance in a wide range of industrial applications and products as they result in the degradation and eventual failure of components and systems both in the processing and manufacturing industries and in the service life of many components. Various technologies can be used to deposit the appropriate surface protection that can resist under specific conditions. They are usually distinguished by coating thickness: deposition of thin films (below 10 to 20 μm according to authors) and deposition of thick films. The latter, mostly produced at atmospheric pressure have a thickness over 30 μm, up to several millimeters and are used when the functional performance and life of component depend on the protective layer thickness. Both coating technology can also be divided into two distinct categories: "wet" and " dry " coating methods, the crucial difference being the medium in which the deposited material is processed. The former group mainly involves electroplating, electroless plating and hot-dip galvanizing while the second includes, among others methods, vapor deposition, thermal spray techniques, brazing, or weld overlays. This chapter deals with coatings deposited by thermal spraying. It is defined by Hermanek (2001) as follows , "Thermal spraying comprises a group of coating processes in which finely divided metallic or non-metallic materials are deposited in a molten or semi-molten condition to form a coating". The processes comprise: direct current (d.c.) arcs or radio frequency (r.f.) discharges-generated plasmas, plasma transferred arcs (PTA), wire arcs, flames, high velocity oxy-fuel flames (HVOF), high velocity air-fuel flames (HVAF), detonation guns (D-gun). Another spray technology has emerged recently ; it is called cold gas-dynamic spray technology, or Cold Spray (CS). It is not really a thermal spray technology as the high energy gas flow is produced by a compressed relatively cold gas (T < 800°C) expanding in a nozzle and will not be included in this presentation

NASA Tech Briefs, September/October 1986

Topics include: NASA TU Services; New Product Ideas; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Fabrication Technology; Machinery; Mathematics and Information Sciences; Life Sciences