Combined effect of inoculation and magnetic arc oscillation on microstructure and tensile behaviour of type 2090 Al–Li alloy weld fusion zones
01 Aug 2000-Science and Technology of Welding and Joining (Taylor & Francis)-Vol. 5, Iss: 4, pp 257-264
TL;DR: In this article, a type 2090 Al-Li alloy was gas tungsten arc welded with two different filler materials corresponding to types 2319 (Al 6.3Cu) and 4043 (Al 5.2Si).
Abstract: In the development of Al–Li alloys for aerospace structures, their behaviour during welding plays an important role. One way of improving weldability is to refine weld solidification structures, which can be achieved by a variety of means. In this work, a type 2090 Al–Li alloy was gas tungsten arc welded with two different filler materials corresponding to types 2319 (Al–6.3Cu) and 4043 (Al–5.2Si). Inoculation with titanium together with arc oscillation through an imposed alternating magnetic field was used to refine the weld fusion zone microstructures. Post-weld aging and tensile testing were employed to assess possible improvements in performance. It was found that the combined treatment of inoculation and magnetic oscillation resulted in fully equiaxed, fine grained structures and that this led to a noticeable increase in aging response and tensile properties, especially ductility.
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TL;DR: In this paper, the authors reviewed two types of cracking, including the factors that affect cracking and the remedies, and proposed a method to deal with the problems of these two types.
Abstract: Solidification cracking can occur in the fusion zone during the solidification of the weld metal Liquation cracking, on the other hand, can occur in the partially melted zone during the solidification of the liquated material These two types of cracking are reviewed in this article, including the factors that affect cracking and the remedies
211 citations
TL;DR: In this article, three beam oscillating patterns that are transversal, longitudinal and circular were studied to join 4mm-thick AA6061-T6 aluminum alloy in butt configuration.
188 citations
TL;DR: In this paper, an ultrasonic grain refining method was proposed to improve the mechanical properties and solidification-cracking resistance of arc welds of Mg alloys AZ31 Mg and AZ91 Mg.
115 citations
TL;DR: In this article, the formability of YAG and diode laser welded blanks of a dual phase (DP) steel with banded martensite was investigated by using limiting dome height (LDH) testing method.
Abstract: In this paper, the formability of YAG and diode laser welded blanks of a dual phase (DP) steel with banded martensite was investigated by using limiting dome height (LDH) testing method. One high strength low alloy (HSLA) steel with equiaxed ferrite matrix was included for comparison. Both steels had a ferrite matrix and dispersed secondary phase, namely martensite and carbide. The failure mode and dome height at fracture were examined on both parent metals and welded blanks. It was found that the failure pattern of DP parent metal was determined by its rolling direction. With increasing plastic strain, voids initiated along interfaces between ferrite/martensite due to decohesion between two phases and propagated preferentially along the interface. For DP welded blanks, dome test failures occurred within the softened zone in the heat affected zone (HAZ) regardless of the orientation between weld and rolling direction. Voids formed at the interfaces between ferrite and tempered martensite. The presence of the softened HAZ zone led to dramatic LDH decrease compared to the parent metal. The diode laser welded blanks had a lower dome height than that of YAG laser welded blanks due to their more severe HAZ softening. In comparison, HSLA parent metal and welded blanks exhibited almost the same LDH values and showed insensitivity to welding process. The failure of HSLA welded blanks initiated from the weld and propagated perpendicular to the unaffected base metal.
44 citations
TL;DR: In this article, the effects of electron beam oscillation techniques (sinusoidal, square, triangular, ramp, circle and elliptical) in controlling Nb segregation, Laves formation and stress rupture behaviour of Inconel 718 electron beam welds are studied.
Abstract: Effects of electron beam oscillation techniques (sinusoidal, square, triangular, ramp, circle and elliptical) in controlling Nb segregation, Laves formation and stress rupture behaviour of Inconel 718 electron beam welds are studied. Effects of various post-weld heat treatments on stress rupture behaviour are compared. Elliptical beam oscillation technique resulted in less Nb segregation and discontinuous and fine Laves in the interdendritic regions compared with other welds and unoscillated beam weld. Response to aging was better for welds made with elliptical oscillated beam compared with welds made with unoscillated beam. Oscillated beam welds exhibited longer rupture life than unoscillated beam welds in both solution treated and aged and directly aged conditions.
32 citations
References
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01 Sep 1981-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: The mechanisms of grain refinement have been examined for magnetically stirred gas tungsten arc (GTA) welds completely penetrating thin sheets of several aluminum alloys in this article.
Abstract: The mechanisms of grain refinement have been examined for magnetically stirred gas tungsten arc (GTA) welds completely penetrating thin sheets of several aluminum alloys. Grain refinement in unstirred welds may be brought about by adding sufficient titanium to produce heterogeneous nucleation by Ti-rich particles. In some alloys magnetic stirring is shown to extend the range of welding conditions which produce a partially equiaxed structure, and to widen the equiaxed fraction of partially equiaxed welds. This is attributed to magnetic stirring lowering the temperature gradient, allowing nucleation and growth of Al-rich grains further ahead of the columnar interface growing in from the fusion boundaries. In alloys with low Ti levels, magnetic stirring may cause refinement by sweeping grains from the partially molten zone ahead of the advancing solidification interface. This mechanism requires that the partially molten zone be sufficiently wide, and that the grain size in this zone remain small.
106 citations
TL;DR: In this paper, the weld beads obtained under (i) continuous current (CC), (ii) pulsed current (PC), and (iii) arc oscillation (AO) conditions for their macro- and microstructural details were compared.
Abstract: Clad 2 mm thick sheets of Russian 1441 grade Al-Li alloys were welded using a gas tungsten arc welding process (GTAW). Comparisons were made between the weld beads obtained under (i) continuous current (CC), (ii) pulsed current (PC), and (iii) arc oscillation (AO) conditions for their macro- and microstructural details. In the case of CC GTAW, sound welds could be produced only under a narrow range of welding parameters. Centre line cracks, which occurred in CC GTAW welds under certain conditions, were halted by switching to PC or AO conditions while the welding was in progress. Microstructural refinement was significant in the case of PC and AO GTA welding.
105 citations
TL;DR: In this paper, the effect of arc oscillation on grain structure and solidification cracking in GTA welds of 5052 aluminum alloy was investigated using a four-pole magnetic arc oscillator and a modified fishbone crack test.
Abstract: The effect of arc oscillation on grain structure and solidification cracking in GTA welds of 5052 aluminum alloy was investigated using a four-pole magnetic arc oscillator and a modified fish-bone crack test. Two different mechanisms of crack reduction were identified: one in the low frequency range of arc oscillation and the other in the high frequency range. The former was the alteration of the orientation of columnar grains, while the latter was grain refining. Neither mechanism was operative in the intermediate frequency range and solidification cracking was severe, especially when the amplitude of arc oscillation was small. Alteration of grain orientation was obtained in welds made with transverse and circular arc oscillations, but not longitudinal arc oscillation. Grain refining, on the other hand, was achieved in welds made with all three types of arc oscillation patterns. The differences between the response of alloy 5052 to arc oscillation and that of alloy 2014 observed previously were discussed.
84 citations
Abstract: Lithium-containing aluminium alloys have reduced density and increased elastic modulus compared with conventional aluminium alloys. Many such alloys are currently under development for aircraft applications, which usually involve mechanical fastening. Consequently, the weldability of lithium-containing aluminium alloys is currently receiving relatively little attention. The weldability of lithium-containing aluminium alloys is reviewed. The vast majority of the welding studies performed have been on the Soviet Al-5 wt% Mg-2 wt% Li alloy, 01420. Alloy 01420 and other lithium-containing aluminium alloys are indeed fusion weldable, and weldments having high joint efficiencies have been made.
46 citations
TL;DR: The weldability of aluminium-lithium alloys is reviewed with emphasis on alloys that are being commercialized: 2090, 8090 and Weldalite™ 049 as mentioned in this paper.
Abstract: The weldability of aluminium-lithium alloys is reviewed with emphasis on alloys that are being commercialized: 2090, 8090 and Weldalite™ 049. These alloys are weldable, although hotcracking susceptibility has been reported for 2090 and 8090 when welded with certain conventional filler alloys. Mechanical property data from weldments made by several techniques are emphasized. Weld-zone porosity problems, discussed at length in a 1985 review in this journal, have largely been controlled by proper weld pretreatment and gas shielding. Interest in the weldability of aluminium-lithium alloys has taken on increased significance because of their potential to reduce the weight of space launch systems, whose fabrication most often involves welding.
42 citations