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연속파형 Nd:YAG 레이저를 이용한 Hastelloy C-276의 용접특성에 관한 연구
나기대,유영태,신호준,오용석,Na, Gee-Dae,Yoo, Young-Tae,Shin, Ho-Jun,Oh, Yong-Seok 대한용접접합학회 2008 대한용접·접합학회지 Vol.26 No.5
Hastelloy C-276, corrosion resistant alloy at high temperature, is used in chemical plant and power generation industry. In this study, process parameter of laser welding for welding property in Hastelloy C-276 using a continuous wave Nd:YAG laser was studied. As the result of experiment, laser welding did not show segregation or crack at heat affected zone compared to conventional GTWA welding. The melting zone showed cell dendritic structure along with welding line. In addition, planer front solidification is occurred from welding structure, and it was progressed to cellular solidification. Optimal process parameter for butt welding was 1.2kW and 2.0 m/min for laser power and welding speed, respectively. While heat input, output density, tensile stress, and longitudinal strain was $441.98{\times}103$ J/cm2, $29.553{\times}103$ W/cm2, 768 MPa, and 0.689, respectively. Lap welding of the same material showed greater discrepancy in tensile property during 1 line and 2 line welding. For 1 line welding, tensile stress was about 320 MPa, and 2 line showed slightly larger tensile stress. However, strain was decreased by 20%. From this result, lap welding of the same material, Hastelloy C-276, with 2 line welding is considered to be more effective process than 1 line welding with consideration of mechanical property.
Welding Characteristics of Lap-Joint Hastelloy C-276 Sheet Metal Using Nd:YAG Laser
김찬규(Chan Kyu Kim),정윤교(Yoon Gyo Jung),조영태(Young Tae Cho) Korean Society for Precision Engineering 2015 한국정밀공학회지 Vol.32 No.8
Hastelloy C-276 composed of Cr, Mo, and Ni is a versatile, corrosion-resistant alloy with numerous industrial applications including its use in nuclear reactors, general chemical plants, and as a superconducting base material. Of especial significance, it can be used as a thin-sheet type whereby lap-joint welding is occasionally necessary. The main welding problems for thinsheet metals are deformation and burn-through from an excessive heat input. Laser welding can minimize these problems because it has a high energy density and low heat effect on the base material. In this study, the laser-welding characteristics of lap-joint Hastelloy C-276 sheet metal were determined. The criteria of the laser-welding variables were chosen using a heat-conduction analysis, and the optimal welding parameters were selected by experimenting with an Nd:YAG laser.
정밀주조 Hastelloy C-276 합금의 미세조직과 기계적 성질에 미치는 W 함량과 열처리의 영향
유병기 ( Byung-ki Yoo ),박흥일 ( Heung-il Park ),배차헌 ( Cha-hurn Bae ),김성규 ( Sung-gyoo Kim ),정해용 ( Hae-yong Jeong ) 한국주조공학회 2017 한국주조공학회지 Vol.37 No.1
The effects of W content and heat treatment on the microstructure and mechanical properties of Hastelloy C-276 alloy investment castings were discussed. As the W content was increased, dendritic microstructure was refined and network type precipitate formed during solidification was distributed on the dendritic grain boundaries. Cr, Fe and Mn were highly segregated in the Nibased dendrite matrix, and Mo, W, C and Si were in the precipitates. Due to the heat treatment, fine granular and flake precipitates were newly formed in the matrix, and unresolved network type precipitates remained on the grain boundary. The network type precipitates and the granular and flake precipitates formed by heat treatment were confirmed to be μ phase intermetallic compounds with similar compositions. Due to the increase of the W content and the heat treatment, hardness and tensile strength were significantly increased. However, tensile strength after aging treatment was decreased with the W content. These results can be explained in that brittle fracturing by the unresolved network type precipitates dispersed in the grain boundary was predominant over ductile fracturing by the dimple ruptures originating from the fine granular precipitates in the matrix.
전기화학적 수소장입 시간에 따른 Hastelloy C-276 의 수소손상 평가
원두일(Doo Il Won),마영화(Young Wha Ma),윤기봉(Kee Bong Yoon) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Hydrogen damage in Hastelloy C-276, which is one of the candidate materials to be used in nuclear hydrogen plant, was studied. For this study, electrochemical hydrogen charging technique and small punch test method were employed. By the former method, two sets of the specimens with four different charging time were prepared. For one set, hydrogen concentration analysis was conducted and for another set, the strength characteristic was assessed by small punch test. The hydrogen concentration increased very significantly according to the charging time. On the other hand, the strength value assessed by small punch test decreased slightly. This result shows that Hastelloy C-276 has little change in the strength even though hydrogen damage occurs.
Corrosion Behavior of Hastelloy C-276 for Carbon-anode-based Oxide Reduction Applications
Jeon, Min Ku,Kim, Sung-Wook,Choi, Eun-Young Korean Radioactive Waste Society 2020 방사성폐기물학회지 Vol.18 No.3
The corrosion behavior of Hastelloy C-276 was investigated to identify its applicability for carbon-anode-based oxide reduction (OR), in which Cl<sub>2</sub> and O<sub>2</sub> are simultaneously evolved at the anode. Under a 30 mL·min<sup>-1</sup> Cl<sub>2</sub> + 170 mL·min<sup>-1</sup> Ar flow, the corrosion rate was less than 1 g·m<sup>-2</sup>·h<sup>-1</sup> up to 500℃, whereas the rate increased exponentially from 500 to 700℃. The effects of the Cl<sub>2</sub>-O<sub>2</sub> composition on the corrosion rate at flow rates of 30 mL·min<sup>-1</sup> Cl<sub>2</sub>, 20 mL·min<sup>-1</sup> Cl<sub>2</sub> + 10 mL·min<sup>-1</sup> O<sub>2</sub>, and 10 mL·min<sup>-1</sup> Cl<sub>2</sub> + 20 mL·min<sup>-1</sup> O<sub>2</sub> with a constant 170 mL·min<sup>-1</sup> Ar flow rate at 600℃ was analyzed. Based on the data from an 8 h reaction, the fastest corrosion rate was observed for the 20 mL·min<sup>-1</sup> Cl<sub>2</sub> + 10 mL·min<sup>-1</sup> O<sub>2</sub> case, followed by 30 mL·min<sup>-1</sup> Cl<sub>2</sub> and 10 mL·min<sup>-1</sup> Cl<sub>2</sub> + 20 mL·min<sup>-1</sup> O<sub>2</sub>. The effects of the chlorine flow rate on the corrosion rate were negligible within the 5-30 mL·min<sup>-1</sup> range. A surface morphology analysis revealed the formation of vertical scratches in specimens that reacted under the Cl<sub>2</sub>-O<sub>2</sub> mixed gas condition.
김찬규(Chan Gyu Kim),정윤교(Yoon Gyo Jung),조영태(Young Tae Cho) Korean Society for Precision Engineering 2017 한국정밀공학회지 Vol.34 No.8
To evaluate the quality of the cross section of Ni alloy thin plate cut by laser, we have proposed an analysis method using SEM image to measure surface roughness of cross section. The surface roughness of the cut area of the thin plate is considerably difficult to analyze using conventional measurement technique such as profile measurement with a probe. When the SEM image is used, the roughness value can be collected quantitatively while judging the surface status qualitatively. A Hastelloy C-276 thin plate with a thickness of 50 μm coated with HTS was cut by Nd:YAG laser, and the state of the cross section was analyzed by applying the proposed method in this research. The optimum laser cutting process condition could be found for the lowest surface roughness.
이호준(Ho Jun Lee),원두일(Doo Il Won),윤기봉(Kee Bong Yoon) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Hydrogen embrittlement sensitivity analysis was conducted for candidate materials of nuclear hydrogen plant such as Alloy 617, SUS316L, Hastelloy C-276. For this study, electrochemical hydrogen charging technique was employed. Hydrogen charging was conducted in 0.5M H₂SO₄ solution and current density of 100 ㎃/㎠ was identically applied to all of the specimens. For the hydrogen charged specimens, hydrogen concentration was examined. From the result of hydrogen concentration analysis, it is found that SUS 316L has the lowest value of hydrogen concentration compare with the other candidate materials. To evaluate the sensitivity of hydrogen embrittlement additional study on strength assessment should be conducted.