Markings in radiographs of 2014 aluminum alloy gas tungsten-arc welds.
Radiographic markings in gas tungsten arc welds of aluminum alloys studied for cause of Laue spots
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Radiographic markings in gas tungsten arc welds of aluminum alloys studied for cause of Laue spots
Handbook has been published which integrates results of 19 research programs involving welding of high-strength aluminum alloys. Book introduces metallurgy and properties of aluminum alloys by discussing commercial alloys and heat treatments. Several current welding processes are reviewed such as gas tungsten-arc welding and gas metal-arc welding.
Bend angles for columbium-base alloys, WC3015 and Cb752, at temperatures between -300 F and +500 F are reported. WC3015 exhibited a bend transition temperature well below -100 F, but was severely embrittled by silicide coatings. Cb 752 exhibited a bend transition temperature below -300 F, and the silicide coating application did not influence bend angle of the substrate. However, coating failure on both alloys was observed at less than 60 deg bend, even at 500 F. The effect of electron beam welding and gas tungsten-arc welding on the properties of WC3015 and Cb752 are also reported. Both techniques are shown to produce a marked reduction in the bend angle of WC3015. Unlike WC3015, ductility is restored in Cb752 after a suitable postweld anneal. Microstructural and hardness tests results for both alloys are reported and discussed.
It is pointed out that over 50 different alloys are used in construction of the space shuttle main engines (SSME). Primary construction of the SSME is by welding or brazing of wrought and cast components. Welding processes involve both gas tungsten-arc welds and electron-beam welds. Electroforming has been developed as a process to fabricate and bond structural members for the SSME. Important aspects in the selection of materials and processes are related to weight saving considerations and the high-pressure hydrogen environment. Special problems and their solution in the case of various engine components are discussed, giving attention to the oxidizer preburner, the high pressure oxidizer turbopump, and the heat exchanger.
Variable-polarity plasma-arc methods produces better welds at lower cost than gas-shielded tungsten-arc welding in assemblies. Weld porosity very low and costs of joint preparation, depeaking, inspection, and weld repair minimized.
The fabrication of prototype titanium alloy primary and secondary mirror support structures for a proposed experimental three-meter space telescope is discussed. The structure was fabricated entirely of Ti-6Al-4V tubing and plate. Fabrication included the development of procedures including welding, forming, and machining. Most of the structures was fabricated by gas-shielding tungsten-arc (GTA) welding with several major components fabricated by high frequency resistance (HFR) welding.
Applicabilities and limitations of three techniques analyzed. NASA technical memorandum discusses physics of electron-beam, gas/ tungsten-arc, and laser-beam welding. From comparison of capabilities and limitations of each technique with regard to various welding conditions and materials, possible to develop criteria for selecting best welding technique in specific application. All three techniques classified as fusion welding; small volume of workpiece melted by intense heat source. Heat source moved along seam, leaving in wake solid metal that joins seam edges together.
Tool that combines clamp with gas nozzle is aid to tungsten/inert-gas (TIG) welding in hard-to-reach spots. Tool holds work to be welded while directing a stream of argon gas at weld joint, providing an oxygen-free environment for tungsten-arc welding.
Portable direct reading spectrometer for monitoring oxygen-hydrogen containing contaminants in gas tungsten arc welding process