Papers by Keyword: Weldability

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Authors: Yuichi Komizo, Hidenori Terasaki
Abstract: Time-resolved X-Ray Diffraction (TRXRD) experments were carried out to identify the phase transformation during welding in-situ. For the martensitic steel weld with different chemical compositions, the solidification behavior was directly analyzed in the time-resolution of 0.01 seconds. The halo pattern from the weld pool gives basis to observe the phase transformation during solidification process of weld. Furthermore, the latest development of TRXRD system was outlined. The importance of detector area was discussed and brand-new TRXRD system in real and reciprocal lattice space was presented.
Authors: Min Sung Hong, Jong Min Kim, Noh Yu Kim
Abstract: Electron beam welding (EBW) has an important role in industrial applications such as semi-conductor and LCD manufactures because of its high performance and accuracy. Since the operation is done in a vacuum room, it is very difficult to test the weldability as well as the correct welding area of the specimen. In this study, a measurement system of the EBW was developed based on the 3-axis LVDT controlled table. In addition, the algorithm to tracking the welding line has been developed. The weldability of the aluminum specimen was tested by a newly developed measurement system with ultrasonic C-scan inspection.
Authors: Pyung Su Kim, So Young Choi, Young Sik Kim, Jong Do Kim
Abstract: Bellows are widely used as parts in industrial machinery such as ships, valves, automotive, semiconductor equipment, flow and pressure sensors, and even in aircraft. Due to the recent depletion of conventional fossil fuels, natural liquified petroleum is increasingly demanded as an alternative energy, which in turn increases the demand for bellows on LNG ships. As the material used the bellows of LNG ships, the STS316L and INCOLOY 825 alloy, resistant to low-temperature embrittlement and corrosion, are used. STS316L is low-carbon stainless steel with a carbon content of less than 0.03%, preventing intergranular corrosion by welding work and maintaining its toughness and strength at a low temperature. In addition, Ni-Fe-Cr-based INCOLOY 825 alloy, containing Mo, Cu and Ti, is an alloy material resistant to general local corrosion in various atmospheres. INCOLOY 825 alloy is widely used for the creation of chemical processing equipment and in pollution-treatment facilities, oil and gas reduction equipment, acid manufacturing plants, pickling plants, nuclear fuel reprocessing and radioactive waste treatment facilities as well as in the bellows of LNG ships. Furthermore this material maintains good mechanical properties across a wide range of temperatures from ultra-low temperatures up to temperature approaching 500 °C. In this study, to assess its quality as a LNG ship bellows material, the STS316L and INCOLOY 825 alloy, used at an ultra-low temperature, the optimal welding conditions were established and its formability was analyzed by conducting an Erichsen test.
Authors: D.W. Walsh, Mark L. Bright, Trevor L. Jackson, D.B. Gibbs
Abstract: Incoloy 903 overlays have been used to provide hydrogen environment embrittlement (HEE) resistance to welds in nickel alloy 718 structures. This is problematic because application of the required overlays has a history of high rejection and rework due to interpass microfissuring. Kovar has been identified as a potential hydrogen resistant replacement for Incoloy 903. A weldability study was initiated to compare the hot crack (microfissure) resistance of the two alloys to determine if substitution of Kovar for Incoloy 903 has the potential to improve the fabricability of HEE overlays. Varestraint testing indicates that Kovar has much higher crack initiation strains for both HAZ and weld metal cracking. Crack initiation strains were approximately 2% for Kovar while Incoloy 903 crack initiation strains were only 0.25% . Maximum crack lengths (MCL) observed on Kovar Varestraint tests were 0.12mm and 0.58mm for base and weld metal respectively, while 903 MCLs were 0.56mm and 2.3mm. Gleeble hot ductility testing indicates that Kovar has a nil ductility range of 7 degrees C while Incoloy 903 has a range of approximately 45 degrees C. The larger range observed for 903 is an indication of its greater crack susceptibility. Fabricability was correlated to material microstructure using optical microscopy, scanning electron microscopy and microprobe analysis.
Authors: I.N. Fridlyander, N.I. Kolobnev, O.E. Grushko, V.G. Davydov
Authors: U. Koch, T. Pfannenmüller, V. Davydov, I.N. Fridlyander, P.J. Winkler
Authors: Min Jung Kang, Cheol Hee Kim
Abstract: When casting ECO Al alloys, Mg-Al2Ca is used as a substitute for elemental Mg during the alloying process. Several previous studies have determined the mechanical and metallurgical properties of the ECO Al 5052 alloy. In this study, the weldability of the ECO Al 5052 alloy was determined. Gas metal arc welding was performed, and the resultant mechanical and metallurgical aspects of the welds in ECO Al 5052 alloy and commercial Al 5052 alloy were examined. In comparison to the commercial Al 5052 alloy specimen, the welds produced in the ECO Al 5052 alloy exhibited a very narrow heat-affected zone and were not softened through grain coarsening. Consequently, almost 100% joint efficiencies were observed in ECO Al alloy welds, in comparison to joint efficiencies of only 82% in conventional Al 5052 alloy welds.
Authors: Marius Bodea, Radu Mureşan
Abstract: The mechanical properties of the welded structures are directly related to the weldability of the steels, thus the estimation of the microstructural constituents in the weld and maximum hardness in the HAZ according to the welding process parameters represent a problem of great interest. The microstructural changes in the HAZ are estimated using a five-parameter logistic function (5PL), which is very accurate in the fitting highly asymmetric data. Also, the same 5PL function can be used in order to predict hardness and toughness in the HAZ based on the heat flow, cooling rates between 800-500 oC and chemical composition of the material. A discussion about the parameters of the 5PL function and fitting experimental data is presented and a studied case for welding S355J2 steel plates is also analyzed.
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