• 한국해양공학회지
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• 제10권1호
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• pp.36-46
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• 1996

This paper deals with determinig the proper friction welding condition and analyzing various mechanical properties of friction welded joints of sintered carbide tool materials(K20, P25, and SKDX5 for the blade part of drill or press punch) to alloy steel (SKH4, SCM440 for the shank part of drill or press punch), the alloy steel to aluminum(A6061 for the interlayer material between the blade part and the shank) and sintered carbide tool materials to alumminum. And also acoustic emission test will be carried out during fiction welding to evaluate the weld quality.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2000년도 특별강연 및 춘계학술발표대회 개요집
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• pp.157-160
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• 2000

• 한국주조공학회지
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• 제25권4호
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• pp.161-167
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• 2005

The experiment of hot dip interaction tests was carried out in order to study the formation behavior of interfacial reaction layer between as-received STD61 hot work tool steel and a commercial pure aluminum melt, Al-xwt.%Fe(x=0.2, 0.5, 0.8 and 1.1) alloys melt and Al-xwt.%Si(x=1.0, 4.0, 7.0 and 10.0) alloys melt, respectively. The results show that the reaction layer, over 300 ${\mu}m$ in thickness, is easily formed by the dissolution of silicon from as-received tool steel. When the iron content in the aluminum alloy is higher than 1.1 wt.%, the thickness of reaction layer decreases below 180 ${\mu}m$ by preventing iron dissolution from the tool steel. The silicon dissolved from tool steel acts as a strong promoter on the formation of reaction layer, but the alloyed silicon in molten aluminum alloys acts as an inhibitor on the formation of reaction layer.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 추계학술대회 논문집
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• pp.310-315
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• 1997

An extensive corrosion study was initiated by galvalume steel sheet manufacturing company to clarify the corrosion behavior of zinc and zinc and zinc-alloy coated automotive sheet steel in out panel and electrical application. Since the early 1980's the use of zinc and aluminum alloy coated steel for vehicular corrosion protection has increased drastically. This paper describes the evaluation of formability, weldability and painted corrosion performance of galvalume steel sheet. This paper presents an overview of the program and some initial test results on the weldability, lifetime of the electrode tip shape of the spot welding and corrosion protection. Galvalume steel sheet improved corrosion performance and spot weldability of galvalume steel has no problem for the variation of welding current. And tip lifetime was changed according to the influence of shape.

• 한국산학기술학회논문지
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• 제9권2호
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• pp.281-285
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• 2008

냉간단조금형(Cold Forging Die)의 다이블록(Dieblock)을 제작하는 방법 중의 하나로, 다이블록 제작용 재료를 면가공 하여 다이블록 상면(上面)을 마스터펀치(Master Punch)인 호브(Hob)로 압입(Indentation) 시켜 절삭가공((Cutting Work)이 아닌 다이호빙(Die Hobbing) 방법으로 임프레션(Impression)을 성형하여 제작하고 있다. 이 방법에 의하여 다이블록의 재료를 합금공구강(Alloy Tool Steel)인 SKD11을 사용하여 제작하고, 스테인리스판(Stainless Sheet Metal)을 제품 재료로 하여 냉간단조가공(Cold Forging Work)을 수행하였더니 6,000 스트로크(Stroke)에서 금형수명(Die Life)을 다 하고 파손되었다. 본 논문에서는 다이블록 재료를 고속도공구강(High Speed Tool Steel)인 SKH51로 교체 제작하고, 탄소강(Carbon Steel)인 S45C를 제품 재료로 하여 냉간단조가공을 수행하였더니 21,000 스트로크에서 금형수명을 다하고 파손되어 종래의 방법과 비교 검토하였을 때 350%의 금형수명 연장 효과를 얻게 되었다.

• Structural Engineering and Mechanics
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• 제73권5호
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• pp.501-513
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• 2020

In the present work, the optimization of machining parameters to achieve the desired technological parameters such as surface roughness, tool radial vibration and material removal rate have been carried out using response surface methodology (RSM). The hard turning of EN19 alloy steel with coated carbide (GC3015) cutting tools was studied. The main problem faced in manufacturer of hard and high precision components is the selection of optimum combination of cutting parameters for achieving required quality of surface finish with maximum production rate. This problem can be solved by development of mathematical model and execution of experiments by RSM. A face centred central composite design (FCCD), which comes under the RSM approach, with cutting parameters (cutting speed, feed rate and depth of cut) was used for statistical analysis. A second-order regression model were developed to correlate the cutting parameters with surface roughness, tool vibration and material removal rate. Consequently, numerical and graphical optimization were performed to obtain the most appropriate cutting parameters to produce the lowest surface roughness with minimal tool vibration and maximum material removal rate using desirability function approach. Finally, confirmation experiments were performed to verify the pertinence of the developed mathematical models.

• 한국공작기계학회논문집
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• 제14권2호
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• pp.42-47
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• 2005

Micro duplex stainless steel is used to denote a fine scale two-phase micro structure consisting austenite and firrite. The development of this structure was done by proper thermo-mechanical processing. The objective of present investigation is to study creep characteristics of this alloy. Since we have little design data about the W behaviors of the alloy. An apparatus has been designed and built fir conducting creep tests under constant load conditions. A series of creep tests on them have been performed to get the basic design data and life prediction of micro duplex stainless steel products and we have gotten the 1311owing results. First the stress exponents decrease as the test temperatures increase. Secondly, the creep activation energy Gradually decreases as the stresses become higher. Thirdly, the constant of Larson-Miller Parameters on this alloy is estimated as about 5. Last, the fiactographs at the creep rupture show both the ductile and brittle fracture modes according to the creep conditions.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.473-477
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• 2000

The experimental study of die-sinking electrical discharge machining(EDM) was conducted for Cold Die Alloy Steel of SKD-11 with rotary electrode according to the peak current of 11A, 15A and 19A, and the duty factor of 0.24, 0.45. dielectric fluid flow through the electrode inside according to the change of electrode internal diameter during the EDM working. Material removal rate(MRR) was increased with flushing & rotation of electrode at the condition for the peak current of 15A, 19a but the MRR is decreased at the flushing only. The more surface roughness was obtained for the case of the flushing & rotation under the peak current of 19A.

• 열처리공학회지
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• 제31권6호
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• pp.290-299
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• 2018

The microstructure of a newly developed alloy tool steel (KV1) for casting cold-work press dies was analyzed using advanced scanning electron microscopy. Its mechanical properties and durability in use as piercing inserts were tested. It contained a continuous network structure which originated from the micro-segregation during solidification and was composed of retained austenite and primary carbides. However, after quenching and tempering, its continuity was destroyed due to the decomposition of austenite. The discontinuous spatial distribution and the smaller amount of primary carbide in the network presented KV1 enhanced ductility compared to the common alloy (HK700). The reduced C and Cr, the addition of V resulted in a small amount of primary carbides which primarily consisted of MC, as well as fine and uniform dispersion of precipitates. Owing to these features, KV1 exhibited delayed initiation of chipping when used for piercing inserts.

• 한국분말재료학회지
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• 제20권4호
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• pp.291-296
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• 2013

SKD11 (ASTM D2) tool steel is a versatile high-carbon, high-chromium, air-hardening tool steel that is characterized by a relatively high attainable hardness and numerous, large, chromium rich alloy carbide in the microstructure. SKD11 tool steel provides an effective combination of wear resistance and toughness, tool performance, price, and a wide variety of product forms. The CNTs was good additives to improve the mechanical properties of metal. In this study, 1, 3 vol% CNTs was dispersed in SKD11 matrix by mechanical alloying. The SKD11+ CNT hybrid nanocomposites were investigated by FE-SEM, particle size distribution, hardness and wear resistance. The CNT was well dispersed in the SKD11 matrix and the mechanical properties of the composite were improved by CNTs addition. It shows good feasibility as cold work die tool.