Rapid Solidification Joining of Intermetallics using Capacitor Discharge Welding

AbstractCapacitor Discharge Welding (CDW) is a rapid solidification joining process capable of cooling rates greater than 106 K/s. The Bureau of Mines is investigating the CDW process as a method of joining TiAl, Fe3A1 and MoSi2. Experimental results show that the fusion zone of the CDW welds is less than 0.1 mm wide, is uniform in composition, and has a cellular solidification microstructure. This paper compares the CDW microstructure of several intermetallics to the microstructures obtained from the gas tungsten arc welding.

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Interfacial structures of dissimilar materials joined by capacitor-discharge welding

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100170402 ◽

1994 ◽

Vol 52 ◽

pp. 534-535

Author(s):

C. P. Doğan ◽

R. D. Wilson ◽

J. A. Hawk

Keyword(s):

Rapid Solidification ◽

Fusion Zone ◽

Dissimilar Materials ◽

Solidification Process ◽

Weld Interface ◽

Capacitor Discharge ◽

Fine Grained ◽

Iron Aluminum ◽

Conductive Ceramics ◽

Capacitor Discharge Welding

Capacitor Discharge Welding is a rapid solidification technique for joining conductive materials that results in a narrow fusion zone and almost no heat affected zone. As a result, the microstructures and properties of the bulk materials are essentially continuous across the weld interface. During the joining process, one of the materials to be joined acts as the anode and the other acts as the cathode. The anode and cathode are brought together with a concomitant discharge of a capacitor bank, creating an arc which melts the materials at the joining surfaces and welds them together (Fig. 1). As the electrodes impact, the arc is extinguished, and the molten interface cools at rates that can exceed 106 K/s. This process results in reduced porosity in the fusion zone, a fine-grained weldment, and a reduced tendency for hot cracking.At the U.S. Bureau of Mines, we are currently examining the possibilities of using capacitor discharge welding to join dissimilar metals, metals to intermetallics, and metals to conductive ceramics. In this particular study, we will examine the microstructural characteristics of iron-aluminum welds in detail, focussing our attention primarily on interfaces produced during the rapid solidification process.

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Arc Characteristics and Weld Bead Microstructure of Ti-6Al-4V Titanium Alloy in Ultra-high Frequency Pulse Gas Tungsten Arc Welding (UHFP-GTAW) Process

Materials Science ◽

10.5755/j01.ms.26.4.22329 ◽

2020 ◽

Vol 26 (4) ◽

pp. 426-431

Author(s):

Wei LI ◽

Gaochong LV ◽

Qiang WANG ◽

Songtao HUANG

Keyword(s):

Titanium Alloy ◽

Fusion Zone ◽

Arc Welding ◽

Gas Tungsten Arc Welding ◽

Weld Bead ◽

Gas Tungsten Arc ◽

Arc Characteristics ◽

Arc Pressure ◽

Gtaw Process ◽

Gas Tungsten

To resolve the problem of grain coarsening occurring in the fusion zone and the heat-affected zone during conventional gas tungsten arc welding(C-GTAW) welded titanium alloy, which severely restricts the improvement of weld mechanical properties, welding experiments on Ti-6Al-4V titanium alloy by adopting ultra-high frequency pulse gas tungsten arc welding (UHFP-GTAW) technique were carried out to study arc characteristics and weld bead microstructure. Combined with image processing technique, arc shapes during welding process were observed by high-speed camera. Meanwhile the average arc pressure under various welding parameters were obtained by adopting pressure measuring equipment with high-precision. In addition, the metallographic samples of the weld cross section were prepared for observing weld bead geometry and microstructure of the fusion zone. The experimental results show that, compared with C-GTAW, UHFP-GTAW process provides larger arc energy density and higher proportion of arc core region to the whole arc area. Moreover, UHFP-GTAW process has the obviously effect on grain refinement, which can decrease the grain size of the fusion zone. The results also revealed that a significant increase of arc pressure while increasing pulse frequency of UHFP-GTAW, which could improve the depth-to-width ratio of weld beads.

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Numerical simulation of heat transfer and fluid flow in a double-sided gas-tungsten arc welding process

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1243/095440503762502305 ◽

2003 ◽

Vol 217 (1) ◽

pp. 87-97 ◽

Cited By ~ 6

Author(s):

H Dong ◽

H Gao ◽

L Wu

Keyword(s):

Heat Transfer ◽

Fluid Flow ◽

Arc Welding ◽

Welding Process ◽

Gas Tungsten Arc Welding ◽

Experimental Results ◽

Staggered Grid ◽

Gas Tungsten Arc ◽

Gas Tungsten ◽

Arc Welding Process

Double-sided arc welding powered by a single power supply is a new type of welding process developed recently at the University of Kentucky. Experiments show that this process has advantages over conventional single-sided arc welding in enhancing penetration, minimizing distortion, improving solidification structure and welding aluminium without the necessity of using filler metal for cracking prevention. In this paper, a three-dimensional transient numerical model is developed for the heat transfer and fluid flow in double-sided gas-tungsten arc welding, including flat-position welding and vertical-up position welding. Based on a non-uniform staggered grid system, the governing equations are solved numerically using the SIMPLEC algorithm. The roles of the surface tension gradient, electromagnetic force and buoyancy force in determining the fluid flow and weld penetration are analysed and compared with those in the conventional arc welding process. The computed weld geometry is compared with experimental results and it is found that the computational results agree with the experimental results with reasonable accuracy.

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The characterization of corrosion resistance in the Ti-6Al-4V alloy fusion zone using a gas tungsten arc welding process

Journal of Materials Research ◽

10.1557/jmr.2009.0444 ◽

2009 ◽

Vol 24 (12) ◽

pp. 3680-3688 ◽

Cited By ~ 8

Author(s):

L.M. Wang ◽

H.C. Lin

Keyword(s):

Corrosion Resistance ◽

Oxide Layer ◽

Fusion Zone ◽

Arc Welding ◽

Welding Process ◽

Heat Treatments ◽

Gas Tungsten Arc Welding ◽

Gas Tungsten Arc ◽

Gas Tungsten ◽

Arc Welding Process

The Ti-6Al-4V sheet alloys were welded by using a common gas tungsten arc welding process. In this work, we study the correlation of corrosion resistance and oxide layer structure produced after commonly used industrial heat treatments. We also study the oxide scales that were formed as a result of the heat-related treatment/aging process. The results indicate that better corrosion resistance of the Ti-6Al-4V alloy weldment can be obtained and significantly improved by a solution treatment plus an artificial aging (ST+AA) treatment, owing to the enhanced intensity of TiO2, V2O5, and Al2O3 oxides that compacted and grew on the surface of fusion zone. The newly found γ-TiAl and α2-Ti3Al particles that nucleated in the fusion zone due to different heat treatments do affect the composition of the oxide layer. The possible mechanism for this oxide layer formation in the fusion zone is discussed.

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Weldability Characteristics of Sintered Hot-Forged AISI 4135 Steel Produced through P/M Route by Using Pulsed Current Gas Tungsten Arc Welding

High Temperature Materials and Processes ◽

10.1515/htmp-2014-0097 ◽

2016 ◽

Vol 35 (1) ◽

pp. 9-19 ◽

Cited By ~ 1

Author(s):

Joby Joseph ◽

S. Muthukumaran ◽

K.S. Pandey

Keyword(s):

Fusion Zone ◽

Heat Input ◽

Arc Welding ◽

Testing Machine ◽

Gas Tungsten Arc Welding ◽

Filler Materials ◽

Pulsed Current ◽

Rectangular Plates ◽

Gas Tungsten Arc ◽

Gas Tungsten

AbstractPresent investigation is an attempt to study the weldability characteristics of sintered hot-forged plates of AISI 4135 steel produced through powder metallurgy (P/M) route using matching filler materials of ER80S B2. Compacts of homogeneously blended elemental powders corresponding to the above steel were prepared on a universal testing machine (UTM) by taking pre-weighed powder blend with a suitable die, punch and bottom insert assembly. Indigenously developed ceramic coating was applied on the entire surface of the compacts in order to protect them from oxidation during sintering. Sintered preforms were hot forged to flat, approximately rectangular plates, welded by pulsed current gas tungsten arc welding (PCGTAW) processes with aforementioned filler materials. Microstructural, tensile and hardness evaluations revealed that PCGTAW process with low heat input could produce weldments of good quality with almost nil defects. It was established that PCGTAW joints possess improved tensile properties compared to the base metal and it was mainly attributed to lower heat input, resulting in finer fusion zone grains and higher fusion zone hardness. Thus, the present investigation opens a new and demanding field in research.

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Characterization and Mechanism of α2-Ti3Al and γ-TiAl Precipitation in Ti-6Al-4V Alloy Following Tungsten Arc Welding

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.520.320 ◽

2012 ◽

Vol 520 ◽

pp. 320-329 ◽

Cited By ~ 1

Author(s):

L.M. Wang ◽

H.C. Lin ◽

C.J. Tsai

Keyword(s):

Fusion Zone ◽

Heat Affected Zone ◽

Arc Welding ◽

Aging Treatment ◽

Annealing Process ◽

Gas Tungsten Arc Welding ◽

Compound Formation ◽

Good Ductility ◽

Gas Tungsten Arc ◽

Gtaw Process

Post-weld heat treatments were carried out in Ti-6Al-4V (Ti-6-4) weldments after a gas tungsten arc welding (GTAW) process. The α2-Ti3Al compound formed in the fusion zone (FZ) following the annealing process, whereas the γ-TiAl, α2-Ti3Al compounds formed in the FZ and heat affected zone (HAZ) respectively following a solution plus aging treatment. These γ-TiAl and α2-Ti3Al that formed in the FZ and HAZ respectively are associated with a low ductility of the Ti-6-4 weldment to 2.8%. In contrast, the only presence of α2-Ti3Al in the FZ still maintains good ductility to 10.8%. Possible mechanisms for γ-TiAl and α2-Ti3Al compound formation in related regions of weldment are discussed.

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