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T. Y. Kuo

Bio: T. Y. Kuo is an academic researcher from National Cheng Kung University. The author has contributed to research in topics: Welding & Inconel. The author has an hindex of 2, co-authored 2 publications receiving 35 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, the weldability and mechanical properties of weldments made with Inconel filler metals I-52 and I-82 in the welding of 690 Alloy Alloy were investigated.
Abstract: This work investigated the weldability and mechanical properties of weldments made with Inconel filler metals I-52 and I-82 in the welding of Inconel alloy 690. Gas tungsten arc welding was used with different multipass sequences. The microstructures of the fusion and heat affected zones were examined and weldment properties were compared by tensile, hardness, and impact tests. Fracture surfaces were examined by scanning electron microscopy. Experimental results indicate that the subgrain structure near the fusion zone centreline was dominated by equiaxed dendrites in I-82 weldments but by columnar dendrites in I-52 weldments. In addition, the I-82 weldments had a finer subgrain structure near the fusion zone centreline and smaller cellular spacing near the fusion line than I-52 weldments. Mechanical test results demonstrate that the I-82 weldments had higher tensile strength (622–630 MPa) with rupture occurring in the base metal. In comparison, the I-52 weldments had lower tensile strength (568–5...

23 citations

Journal ArticleDOI
TL;DR: In this article, the effects of adding different quantities of Nb (0·1, 1·03, 2·49, and 3·35 wt-%) to the flux of electrodes used in welding Inconel alloy 690 on the microstructure, mechanical properties, and corrosion behaviour of the resulting weldments were investigated.
Abstract: The present work investigates the effects of adding different quantities of Nb (0·1, 1·03, 2·49, and 3·35 wt-%) to the flux of electrodes used in welding Inconel alloy 690 on the microstructure, mechanical properties, and corrosion behaviour of the resulting weldments. Inconel filler metal I–52 coated with flux was used as the welding electrode. Weldments were butt welded using a manual shielded metal arc welding process. The experimental results indicated that the subgrain structure of the fusion zone was primarily dendritic. Niobium was depleted at the dendritic cores and enriched in the interdendritic regions. A small heat affected zone with typical coarse grains, which subsequently formed ghost grain boundaries, was present. With increasing Nb, the welds tended to show a finer subgrain structure and smaller dendritic spacing. Niobium rich segregants in the form of small particles formed in interdendritic spaces, providing the sites for microvoid formation by rupture. Correspondingly, the tensi...

14 citations


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Book
05 Oct 2009
TL;DR: In this article, the authors present an overview of the history of Ni-base Alloy Classification and its application in Solid-Solution-Strengthened Alloy Alloys and Welding Metallurgy.
Abstract: Preface. 1. Introduction. 1.1 Ni-base Alloy Classification. 1.2 History of Nickel and Ni-base Alloys. 1.3 Corrosion Resistance. 1.4 Nickel Alloy Production. 2. Alloying Additions, Phase Diagrams, and Phase Stability. 2.1 Introduction. 2.2 General Influence of Alloying Additions. 2.3 Phase Diagrams for Solid-Solution Alloys. 2.4 Phase Diagrams for Precipitation Hardened Alloys--gamma' Formers. 2.5 Phase Diagrams for Precipitation-Hardened Alloys--gamma" Formers. 2.6 Calculated Phase Stability Diagrams. 2.7 PHACOMP Phase Stability Calculations. 3. Solid-Solution Strengthened Ni-base Alloys. 3.1 Standard Alloys and Consumables. 3.2 Physical Metallurgy and Mechanical Properties. 3.3 Welding Metallurgy. 3.4 Mechanical Properties of Weldments. 3.5 Weldability. 3.6 Corrosion Resistance. 3.7 Case Studies. 4. Precipitation Strengthened Ni-base Alloys. 4.1 Standard Alloys and Consumables. 4.2 Physical Metallurgy and Mechanical Properties. 4.3 Welding Metallurgy. 4.4 Mechanical Properties of Weldments. 4.5 Weldability. 5. Oxide Dispersion Strengthened Alloys and Nickel Aluminides. 5.1 Oxide Dispersion Strengthened Alloys. 5.2 Nickel Aluminide Alloys. 6. Repair Welding of Ni-base Alloys. 6.1 Solid-Solution Strengthened Alloys. 6.2 Precipitation Strengthened Alloys. 6.3 Single Crystal Superalloys. 7. Dissimilar Welding. 7.1 Application of Dissimilar Welds. 7.2 Influence of Process Parameters on Fusion Zone Composition. 7.3 Carbon, Low Alloys and Stainless Steels. 7.4 Postweld Heat Treatment Cracking in Stainless Steels Welded with Ni-base Filler Metals. 7.5 Super Austenitic Stainless Steels. 7.6 Dissimilar Welds in Ni-base Alloys - Effect on Corrosion Resistance. 7.7 9%Ni Steels. 7.8 Super Duplex Stainless Steels. 7.9 Case Studies. 8. Weldability Testing. 8.1 Introduction. 8.2 The Varestraint Test. 8.3 Modified Cast Pin Tear Test. 8.4 The Sigmajig Test. 8.5 The Hot Ductility Test. 8.6 The Strain-to-Fracture Test. 8.7 Other Weldability Tests. Appendix A Composition of Wrought and Cast Nickel-Base Alloys. Appendix B Composition of Nickel and Nickel Alloy Consumables. Appendix C Corrosion Acceptance Testing Methods. Appendix D Etching Techniques for Ni-base Alloys and Welds. Author Index. Subject Index.

778 citations

Journal ArticleDOI
01 Dec 2014-Vacuum
TL;DR: In this article, electron beam welding of dissimilar Inconel 625 and SS 304L alloys was successfully performed by employing optimized beam welding parameters, the welded joint was characterized using SEM/EDS, XRD and micro-hardness tester.

93 citations

Journal ArticleDOI
TL;DR: In this article, the effects of Ti addition on the weldability, microstructure and mechanical properties of a dissimilar weldment of Alloy 690 and SUS 304L were investigated.

73 citations

Journal ArticleDOI
TL;DR: In this article, an experimental and theoretical program of research is undertaken with the aim of developing a quantitative understanding of the solidification behavior under a wide range of temperature gradients and solidification growth rates.
Abstract: The solidification behavior of the advanced nickel-base alloys, such as Inconel® Alloy 690, is important for understanding their microstructure, properties, and eventual service behavior in nuclear power plant components. Here, an experimental and theoretical program of research is undertaken with the aim of developing a quantitative understanding of the solidification behavior under a wide range of temperature gradients and solidification growth rates. The temperature gradient and solidification rates vary spatially by several orders of magnitude during keyhole mode laser welding. Therefore, the solidification structure is experimentally characterized from microscopic examinations of the resulting fusion zones and correlated with fundamental solidification parameters to provide a widely applicable solidification map that can be employed for a broad range of solidification processes. The cell and secondary dendrite arm spacings are quantitatively correlated with cooling rates. An Alloy 690 solidification map, which illustrates the effect of temperature gradient and solidification rate on the morphology and scale of the solidification structures, is also presented.

65 citations

Journal ArticleDOI
TL;DR: In this article, microcracks occurred within 300 μm from the fusion line of the subsequent weld bead and propagated along the solidification boundaries in the gas tungsten arc multipass weld metal of alloy 690.
Abstract: Microcracking behaviour in the gas tungsten arc multipass weld metal of alloy 690 was investigated. The majority of microcracks occurred within about 300 μm from the fusion line of the subsequent weld bead and propagated along the solidification boundaries in the multipass weld metal. The morphology of the crack surface indicated the characteristic texture of ductility dip cracking. The microcracking susceptibility of the reheated weld metal was evaluated via the spot Varestraint test using three different filler metals having varying contents of impurity elements such as P and S. Microcracking occurring in the spot Varestraint tests consisted predominantly of ductility dip cracking, with a small amount of liquation cracking. The ductility dip cracking temperature range was about 1350–1600 K in the weld metal FF1, and narrowed in the order of weld metals FF1>FF3>FF5. The ductility dip cracking susceptibility was reduced with decreasing contents of impurity elements in the filler metal. It was conc...

51 citations