• Journal of Welding and Joining
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• v.24 no.3
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• pp.49-54
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• 2006

The Plasma Transferred Arc (PTA) overlaying method is lately introduced as one of the most useful surface modification method of the engine component. In this paper, the characteristics of the Co-base and Ni-base super alloy overlay layers by PTA method were investigated through the metallurgical, abrasive and cavitation erosion test. Experimental results showed that the abrasive wear resistance of the Co-base Stellite 6 overlayer was the most superior and followed in order of Nimonic 80A, Inconel 625 and Inconel 718. However, the cavitation erosion characteristic of the Stellite 6 overlayer was the most inferior and it was better in order of Inconel 625, Inconel 718 and Nimonic 80A.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.7
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• pp.852-856
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• 2007

The Plasma Transferred Arc(PTA) overlay welding method is lately introduced as one of the most useful surface overlay method of the engine component. In this paper, the overlay welding method on the Nimonic super alloy was established by the PTA overlay welding process using the same super alloy powder. The characteristics of the Co-base and Ni-base super alloy overlay layers were investigated through the metallurgical, abrasive and cavitation erosion test. The abrasive and cavitation characteristics were investigated at room and high temperature.

• Journal of Powder Materials
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• v.27 no.1
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• pp.8-13
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• 2020

In this study, we investigated the effects of precipitates and oxide dispersoids on the high-temperature mechanical properties of oxide dispersion-strengthened (ODS) Ni-based super alloys. Two ODS Ni-based super alloy rods with different chemical compositions were fabricated by high-energy milling and hot extrusion process at 1150 ℃ to investigate the effects of precipitates on high-temperature mechanical properties. Further, the MA6000N alloy is an improvement over the commercial MA6000 alloy, and the KS6000 alloy has the same chemical composition as the MA6000 alloy. The phase and microstructure of Ni-based super alloys were investigated by X-ray diffraction and scanning electron microscopy. It was found that MC carbide precipitates and oxide dispersoids in the ODS Ni-based super alloys developed in this study may effectively improve high-temperature hardness and creep resistance.

• Korean Journal of Materials Research
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• v.25 no.11
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• pp.642-646
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• 2015

Super alloys, which can be divided into three categories, i.e. Ni-base, Co-base, and Fe-base alloys, are widely used for high temperature applications. Since superalloys contain many alloying elements and precipitates, their chemistry and processing parameters need to be carefully designed. In this study, we designed a new Ni alloy to prevent corrosion due to water vapor and gases at high temperatures. The new alloy was designed using the theoretical value of the resulting energy electronic state calculation($DV-X{\alpha}$ method). The components that were finally used were Cr, Mo, and Ti, with Ni as a base. For these alloys, elements were selected in order to compare their values with that of the average theoretical basis for an Inconel 625 alloy. Finally, two kinds of Ni alloy were designed: Ni-28Cr-4Mo-2Ti and Ni-20Cr-10Mo-1Ti.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.4
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• pp.396-405
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• 2002

The purpose of this study was to evaluate the effects of four metal surface treatments on the shear bond strength of reline resin to Ni-Cr alloy. The denture base metal used in this study was Ni-Cr alloy(Ticonium Premium 100. Ticonium Co., U.S.A.). 120 specimens were divided into five metal surface treatments: sandblasting only, MR. BOND(Tokuyama Corp.. Japan), Cesead Opaque Primer(Kuraray Co., Japan), METALPRIMER II(GC Corp., Japan) and Super-Bond C&B(Sun Medical Co., Japan) after sandblasting. They were bonded with one of three reline resins Mild Rebaron(GC Corp., Japan), Mild Rebaron LC(GC Corp., Japan) and Meta Base M(Sun Medical Co., Japan). Then they were thermocycled 1,000 times at temperature of $4^{\circ}C$ and $60^{\circ}C$. The shear bond strengths were measured using the universal testing machine(Instron, Model 4301, England) with a cross-head speed of 2 mm/min. The results were as follows : 1. All metal primers and adhesive cement significantly improved the bond strength of reline resin to Ni-Cr alloy compared with sandblasted specimens. 2. In Mild Rebaron and Mild Rebaron LC. Cesead Opaque Primer showed the highest bond strength, but the differences among Cesead Opaque Primer, MR. BOND and METALPRIMER II were not significant. The bond strength of Cesead Opaque Primer was significantly different with that of Super-Bond C&B. 3. In Meta Base M, Super-Bond C&B showed the highest bond strength, but there was no difference between Super-Bond C&B and three metal primers. 4. There was no difference in the bond strength between Mild Rebaron and Mild Rebaron LC when metal surface was treated with the same method. 5. The bond strengths of Mild Rebaron and Mild Rebaron LC treated with Cesead Opaque Primer were higher than that of Meta Base M. The bond strengths of Mild Rebaron treated with MR. BOND and METALPRIMER II was higher than that of Meta Base M, However, there was no difference among three reline resins treated with Super-Bond C&B.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.139-144
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• 2002

Ti-50.9at%Ni wires were welded using pulsed YAG laser. The laser welded wires were tested for investigating the shape memo교 effect and the ability of super elasticity. The fatigue properties of the welded wires were investigated using the rotary bending fatigue tester specially designed for wires. Moreover, the effect of defocusing distance during laser welding on the static and fatigue properties was investigated. The shape memory effect and super elasticity of the laser welded wires were approximately identical with that of base metal at the test temperature below 353K. However, the welded wires were broken within elastic limit at the test temperature above 353k. Under the cyclic bending loading conditions, the welded wires could be useful only below the elastic limit, while the base metal had sufficient fatigue life even the stress induced M-phase region. The fatigue strength of the welded wires was about half of that of the base metal. The deterioration of the static and fatigue properties in the welded wires was proven to be from the large difference of the transformation behavior between the base metal and welded part that is caused by vaporization of Ni-content at the welded part during the welding process. The defocusing distance below 3mm acted more largely on lowering the strength of the welded wires than that of 6mm or 8mm.

• Proceedings of the KWS Conference
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• 2003.11a
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• pp.74-76
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• 2003

• International Journal of Korean Welding Society
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• v.3 no.1
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• pp.39-44
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• 2003

The welded specimens were made by butt welding of the 2 wires of 50mm length using the pulsed YAG laser. The laser welded wires were tested for investigating the shape memory effect and the ability of super elasticity. The fatigue properties of the welded wires were investigated using the rotary bending fatigue tester specially designed for wires. Moreover, the effect of defocusing distance during laser welding on the static and fatigue properties was Investigated. The shape memory effect and super elasticity of the laser welded wires were approximately identical with that of base metal at the test temperature below 353K. However, the welded wires were broken within elastic limit at the test temperature above 353k. Under the cyclic bending loading conditions, the welded wires could be useful only below the elastic limit, while the base metal had sufficient fatigue life even the stress induced M-phase region. The fatigue strength of the welded wires was about half of that of the base metal. The deterioration of the static and fatigue properties in the welded wires was proven to be from the large difference of the transformation behavior between the base metal and welded part that is caused by vaporization of Ni-content at the welded part during the welding process. The defocusing distance below 3mm acted more largely on lowering the strength of the welded wires than that of 6mm or 8mm.

• Journal of the Korean institute of surface engineering
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• v.32 no.2
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• pp.100-108
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• 1999

The microstructure and corrosion properties of Al-Si diffusion coated PWA1426 alloy have been investigated. Experimental variables are included temperatures of heat-treatment and coating thickness. The microstructure of coated layer and corrosion properties were analysed by SEM, EDS and hot corrosion test. Two major processes have been found to contribute to microstructural changes in the coating. These are, firstly, the transformation of the NiAl to other $Ni_2Al_3$-based phase and secondly, the precipitation of Cr containing phases. Specimens heat treated at $1080^{\circ}C$ showed superior corrosion resistance to heat treated at $880^{\circ}C$. These increase in life was attributed to the transformation of NiAl and increased coating thickness of PWA1426 alloy.

• Journal of Power System Engineering
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• v.21 no.6
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• pp.13-20
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• 2017

Ni-base superalloy Haynes 282 was developed as a gas turbine material for use in the ultra-super-critical stage (USC) of next-generation coal-fired power plants. Temperatures in the USC stage exceed $700^{\circ}C$ during operation. In spite of its important role Haynes 282 in increasing the performance of high-pressure turbines, as a result of its high-temperature capability, there is little information on the microstructure, deformation mechanism, or mechanical properties of the cast condition of this alloy. The aim of present study is to examine the creep properties of cast alloy and compare with wrought alloy. The ${\gamma}^{\prime}-precipitates$ were coarsen with the increase of aging time ranging from 8 to 48 hrs. A creep test performed at $750^{\circ}C$ showed faster minimum creep rate and shorter rupture lifetime with the aging time. A creep test performed showed only a slight difference in the rupture life between cast and wrought products. Based on the creep test results, the deformation mechanism is discussed using fractographs.