• Proceedings of the Korean Society of Laser Processing Conference
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• 1998.11a
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• pp.66-70
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• 1998

• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.201-206
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• 2001

The evolution of textures in Fe-Ni alloy thin films fabricated by PVD using a sputtering method was investigated with parameters such as deposition time and chemical composition. The textures of the as-deposited films were characterized by fibre-type. In Invar alloy(Fe-36.5 wt%Ni) thin film, the <110>//ND fibre texture as a starting component changed to the <210>//ND fibre texture with increasing deposition time. In Permalloy(Fe-81 wt%Ni) thin film, a mixture of the <221>//ND and <311>//ND fibres developed at the early stage of deposition, and then transformed to the <210>//ND fibre with increasing deposition time. These texture changes were discussed in terms of relationship with the microstructural evolution of the films.

• Journal of Welding and Joining
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• v.12 no.2
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• pp.119-127
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• 1994

용접 이음부는 토우부의 응력집중에 의해 피로강도가 저하된다는 것은 잘 알려져 있는 사실이다. 이 때문에 용접 이음부의 피로강도 개선을 위하여 여러 방법이 제안되어 있으나 본 연구에서는 강을 가열후 급랭하여 극저탄소강의 피로강도 개선에 미치는 시효의 영향을 조사하였다. 탄소 함유량 0.019-0.080% 범위의 8종의 탄소강을 용해 제조하여 압연한 후 피로시험편을 가공하였다. 이 시험편을 $A_1$점 이하 $700^{\circ}C$로 가열하여 급랭 시효에 의한 저탄소강의 피로강도에 미치는 탄소함유량의 영향을 조사하였다. $700^{\circ}C$로부터의 급랭 및 시효에 의하여 인장강도 및 피로강도는 노랭, 공랭재의 경우에 비하여 훨씬 높아짐을 알 수 있었다. 또한 급랭후의 시효에 의한 피로강도 향상 효과가 가장 크게 나타나는 것을 페라이트의 탄소고용한도 0.02%에 가까운 합금 조성을 갖는 경우이었다.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.115-116
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• 2006

• Korean Journal of Materials Research
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• v.2 no.6
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• pp.436-442
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• 1992

When $N_2$was used as shielding gas during the formation of Ti surface-alloyed layer by irradiation of $CO_2$laser beam on steel, TiN and F$e_2$Ti were formed regardness of carbon-content in steel. When Ti content was increased in low carbon-content steel, formation of martensitic structure was suppressed due to increase of critical cooling rate for martensitic transformation. In case of high-carbon steel, even though Ti content was about 1.5% in alloyed layer, hardness was increased by formation of martensitic structure instead of ferrite. In addition to that structure, hardness was incrreased further by precipitation of TiC in Ti alloyed-layer of high carbon-steel.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.4
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• pp.426-431
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• 2008

The high-strength low-alloy(HSLA) steels have low carbon contents($0.05{\sim}0.25%$ C) in order to produce adequate formability and weldability, and they have manganese contents up to 1.7%. Small quantities of silicon, chromium, nickel, copper, aluminum, molybdenum are used in various combinations. The results contained in this paper can provide the valuable information on the development of $-40^{\circ}C$ low temperature HSLA. Furthermore, the present experimental data will provide important database for casting steel materials of the offshore structure.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.207-210
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• 2008

The effects of boron additions in steels have long been recognized as very important, mainly with respect to hardnability of heat treatable steels. we investigated the effect of the microstructure and mechanical properties with cooling condition after heat treatment of the boron-treated(${\fallingdotseq}8{\sim}18ppm$) low carbon(${\fallingdotseq}0.2%C$) low alloy steel. The specimens were austenitised for 10 min at $910^{\circ}C$, cooled for the various periods of time from 10 sec to 30 sec or with water after forming for 15 sec. After cooling, mechanical properties were measured by tensile test and hardness test. For analysis of microstructure, Optical were carried out.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.172-175
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• 2006

Effects of deformation at austenite non-recrystallization region and cooling rate on the microstructure and mechanical properties of low carbon (0.06 wt. %) high strength low alloy steels have been investigated. Average grain size decreased and polygonal ferrite transformation promoted with increasing deformation amount due to increase of ferrite nucleation site. As cooling rate increased, the major microstructure changed from polygonal ferrite to acicular ferrite and the fraction of M/A constituents gradually increased. Discontinuous yielding occurred in highly deformed specimen due to the formation of polygonal ferrite. However, small grain size of highly deformed specimen caused lower ductile-to-brittle transition temperature than slightly deformed specimen.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.122-122
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• 2009

금속기판과 액체금속의 젖음성은 일반적으로 액적법 (sessile drop)에 의해 고체와 액체간의 접촉각 측정을 통해서 알 수 있다. 이러한 방법에 의한 젖음성 실험결과는 고체와 액체계면에서의 반응이 무시될 수 있는 경우에 적용가는 하지만 연속용용도금공정과 같이 용융된 금속내부로 강판이 인입되는 과정에서 계면반응이 동적으로 진행되는 과정에서의 젖음성을 모사하기에는 이러한 방법의 신뢰성이 떨어지는 문제점이 있다. 따라서 본 연구에서는 실제 용융도금공정과 유사하게 소둔열처리된 저탄소강판이 환원성분위기내에서 Zn 및 Zn-Al 용융도금욕 내부로 연속적으로 인입되는 과정에서의 젖음력 및 접촉각 등의 측정을 통해 실제 도금공정상의 도금성과 젖음성의 연관성을 규명하고자하였다. 연구결과 일반적인 Zn 도금욕의 경우 젖음성이 양호하지만 Al함량이 높은 경우에는 젖음성이 좋지 못한 것으로 나타났다.

• Laser Solutions
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• v.2 no.2
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• pp.34-41
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• 1999

A RS840 $CO_2$laser and a powder auto-feeding apparatus have been used to deposit single tracks of Ni-base superalloy on low carbon steel. In this paper, the effects of laser cladding parameters on clad geometry, dilution and microhardness are studied. As a results, the w/h ratio of the clad layer increases with decreasing powder feed rate and increasing laser scan speed. Increase of powder density and decrease of specific energy have little effect on dilution. It was found that the clad layer of the highest hardness has a structure in which fine and leaf like phases are dispersed in ${\gamma}$Ni matrix.