• 대한기계학회논문집A
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• 제38권4호
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• pp.427-436
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• 2014

이 연구에서는 STD61 열간금형강 상부에 생성되는 하드페이싱층에 적합한 하드페이싱 재료와 두께를 3 차원 비정상 열전달 및 열응력 해석을 통하여 예측하고자 한다. Stellite6, Stellite21과 19-9DL 초합금을 하드페이싱 재료로 적용하였다. 하드페이싱 재료와 두께가 하드페이싱된 시편 내부 온도, 열응력 및 변형률 분포 변화에 미치는 영향에 대하여 분석하였다. 이 결과로부터 큰 열전도도를 가지는 재료로 얇은 하드페이싱 층을 생성하는 것이 열전달 특성 측면에서는 효과적인 것을 알 수 있었다. 또한, Stellite21 초합금으로 2 mm 두께의 하드페이싱부를 STD61 열간 금형강 상부에 생성할 경우, 하드페이싱부와 기저부의 경계부에서 유효응력 및 주변형률 편차가 최소화됨을 알 수 있었다. 이 결과들로부터 STD61 열간금형강에 적합한 하드페이싱 재료와 두께를 예측할 수 있었다.

• Journal of Welding and Joining
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• 제28권3호
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• pp.79-85
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• 2010

Hardfacing is one of the frequently applying method to increase surface hardness in hot forging die. Recently, hardfacing receives great attention due to it's repair availability and low cost. In hot forging die, crack resistance and thermal shock resistance have been considered as major properties, However there are few studies for the assessment of these properties. So, it is necessary to establish the assessment method for crack resistance and thermal shock resistance in hardfacing for hot forging die. In this study, flux cored arc welding was applied to make hardfacing welds. Three point bending test was carried out to assess hardfacing weld's crack resistance, and high temperature bending test using salt bath was developed for thermal shock resistance. Consequently, it was possible to assess crack resistance and thermal shock resistance of hardfacing welds for hot forging die quantitatively.

• 한국재료학회지
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• 제12권7호
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• pp.550-554
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• 2002

The effect of Mn on cavitation erosion resistance and the sliding wear resistance of Fe-base hardfacing NewAlloy was investigated. Mn is known to decrease stacking fault energy and enhance the formation of $\varepsilon$-martensite. Cavitation erosion resistance for 50 hours and sliding wear resistance for 100 cycles were evaluated by weight loss. Fe-base hardfacing NewAlloy showed more excellent cavitation erosion resistance than Mn-added NewAlloys. $\Upsilon-\alpha$' phase transformation that can enhance erosion resistance by matrix hardening occurred in every specimens. But, only in Mn free Fe-base hardfacing NewAlloy, the hardened matrix could repress the propagation of cracks that was initialed at the matrix-carbides interfaces more effectively than Mn-added NewAlloy The Mn free Fe-base hardfacing NewAlloy showed better sliding wear resistance than Mn-added alloys. Mn-addition up to 5wt.% couldn't increase the sliding wear and cavitation erosion resistance of Fe-base hardfacing alloy because it didn't make $\Upsilon\to\varepsilon$ martensite phase transformation. Therefore, it is considered that the cavitation erosion and the sliding wear resistance can be improved due to $\Upsilon\to\varepsilon$ martensite phase transformation when Mn is added more than 5wt.% in Fe-base hardfacing alloys.

• Journal of Welding and Joining
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• 제15권4호
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• pp.154-165
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• 1997

Abrasive wear characteristics of high Cr white cast iron-based hardfacing were investigated using the rubber wheel abrasion wear test method according with the ASTM G65-85. Mild steel was also tested for comparison with high Cr cast iron hardfacing. Wear experiments, where the applied force, wheel revolution rate and abrasive powder feed rate were selected as test valuables, were planned and analyzed by response surface method to evaluate wear statistically and quantitatively. Weight loss of high Cr cast iron hardfacing was mostly affected by the applied force and wheel revolution rate, and little by the powder feed rate. Weight loss of mild steel was greatly affected by the wheel revolution rate and powder feed rate, and slowly and steadily increased with the applied force. Abrasive wear mechanism of high Cr cast iron and mild steel was discussed in the light of the wear test results.

• Journal of Welding and Joining
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• 제20권4호
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• pp.551-556
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• 2002

Solid particle erosion wear characteristics of high Cr white iron hardfacing were investigated using the erosion wear test method according with the ASTM G76-95. Wear experiments, where the blast angle, blast distance and blast pressure were selected as test variables, were planned and analyzed by response surface method (RSM to evaluate the wear loss statistically and quantitatively. The measured wear losses well coincided with the calculated ones by the experimental equation. The wear loss of high Cr cast iron hardfacing was increased with blasting pressure, but affected in a complicated way by the blasting angle and distance. Erosion wear of high Cr cast iron hardfacing could be well predicted by RSM analysis of wear variables.

• International Journal of Korean Welding Society
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• 제3권2호
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• pp.1-6
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• 2003

The abrasion and impact wear resistance were investigated on the hardfacing weld dispersed with the recycled hard metal(HM). The HM was composed of the tungsten carbide(WC) reinforced metal matrix composite. The cored wire filled with the 35 wt.％ HM and 0­6 wt.％ of the alloying element, Fe­75Mn­7C(FeMnC), was used for the gas metal arc(GMA) welding. The FeMnC addition to the 35 wt.％ HM did not improve the abrasion wear property since the amount of the tungsten carbide formed was decreased with respect to the FeMnC amount. However, the 6 wt.％ FeMnC addition to the 35 wt.％ HM exhibited the better impact wear resistance than the hardfacing weld by the 40 wt.％ HM.

• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 2000년도 추계학술발표대회 논문개요집
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• pp.46-50
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• 2000

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 춘계학술발표대회 개요집
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• pp.115-117
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• 2002

• Nuclear Engineering and Technology
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• 제52권3호
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• pp.589-596
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• 2020

Many components in the assembly section of Sodium-cooled Fast Reactor are made of good corrosionresistant 316 LN Stainless Steel material. To avoid self-welding of the components with the coolant sodium at elevated temperature, hardfacing is inevitable. Ni-based colmonoy-5 is used for hardfacing due to its lower dose rate by Plasma Transferred Arc process due to its low dilution. Since Ni-Cr-B-Si alloy becomes very fluidic while depositing, the major height of the weld overlay rests inside the groove. Hardfacing is also done over the plain surface where grooving is not possible. Therefore, grooved and ungrooved hardfaced specimens were prepared at different travel speeds. Fe content at every 100 ㎛ of the weld overlay was studied by Energy Dispersive Spectroscopy and also the micro hardness was determined at those locations. A correlation between iron dilution from the base metal and the micro hardness was established. Therefore, if the Fe content of the weld overlay is known, the hardness at that location can be obtained using the correlation and vice-versa. A new correlation between micro hardness and dilution coefficient is obtained at different locations. A comparative study between those specimens is carried out to recommend the optimum travel speed for lower dilution.

• 한국레이저가공학회지
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• 제7권2호
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• pp.27-38
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• 2004

Laser remelting of surface of cobalt-based hardfacing alloy can eliminate impurities and cracks and improve the wear resistance. In this present study, Stellite ${\sharp}6\;and\;{\sharp}21$ harfacing alloys were remelted by a 3kW CO2 laser. Hardness distribution and microstructures in the laser remelted zone was investigated. Our results showed that in proper laser parameters laser remelted surface of hardfacing alloy had more refined microstructure and more increased micro-hardness than the base material.