• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2009년 추계학술발표대회
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• pp.95-95
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• 2009

Zinc coatings provide the most effective and economical way of protecting steel against corrosion. There are three types of galvanizing lines typically used in production line in galvanizing industries,Galvanize (GI) coating (Zn-0.1-0.3%Al), Galfan coating (Zn-5%Al), Galvalume(GL) coating (45%Zn-Al). In continuous Galvanizing lines, the immersed bath hardware (e.g. bearings, sink, stabilizer, and corrector rolls, and also support roll arms and snout tip) are subjected to corrosion and wear failure. Understanding the reaction of these materials with the molten Zn alloy is becomes scientific and commercial interest. To investigate the reaction with molten Zn alloys, static immersion test performed for 4, 8, 16, and 24 Hr. Two different baths used for the static immersion, which are molten Zn and molten Zn-55%Al. Microstructures characterization of each of the materials and intermetallic layer formed in the reaction zone was performed using optical microscope, SEM and EDS. The thickness of the reaction layer is examined using image analysis to determine the kinetics of the reaction. The phase dominated by two distinct phase which are eutectic carbide and matrix. The morphology of the intermetallic phase formed by molten Zn is discrete phase showing high dissolution of the material, and the intermetallic phase formed by Zn-55wt%Al is continuous. Aluminum reacts readily with the materials compare to Zinc, forming iron aluminide intermetallic layer ($Fe_2Al_5$) at the interface and leaving zinc behind.

• 한국분말재료학회지
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• 제26권3호
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• pp.214-219
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• 2019

In this study, the microstructure and characterization of an overlay welding layer using Fe-based composite powders are reported. The effects of the number of passes and composition of powders on the microstructure and mechanical properties are investigated in detail. The welding wire and powders are deposited twice on a stainless-steel rod using a laser overlay welding process. The microstructure and structural characterization are performed by scanning electron microscopy and X-ray diffraction. The mechanical properties of the first and second overlay layers are analyzed through the micro-Vickers-hardness tester and abrasion wear tester. In the second overlay layer, the hardness and specific wear are approximately 840 Hv and $2.0{\times}10^{-5}mm^3/Nm$, respectively. It is suggested that the increase of the volume fractions of $(Cr,Fe)_7C_3$ and NbC phases in the second welding layer enhances the hardness and wear resistance.

• Journal of Welding and Joining
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• 제20권2호
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• pp.82-89
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• 2002

In order to clarify hot cracking phenomena occurred in Inconel 690 welds and it's prevention, in this study, the cracking behavior and the influence of welding variables on cracking in Inconel 690 overlay welds on Mn-Ni-Cr-Mo steel(SA 508 cl.3) for pressure vessel were investigated by using mock-up test. The main results are as follows: The cracks in Inconel 690 overlay welds were mainly generated near the start and the end part of welding beads adjacent to STS 309L welded outside of Inconel 690 welds. Most of the cracks showed typical solidification crack, and also it was assumed that there was possibility of liquation cracking in HAZ. The existence of Nb constituents or concentration of Nb was recognized on the fracture facets of the solidification cracks in the welds by SMAW. Therefore Nb was considered to be the main factor of the solidification cracking. As the weld heat input was more increased and the weld bead length was longer, the extent of cracking was more increased. Moreover the extent of cracking was considerably decreased by changing of welding sequence to the start and the end part of welds. Hot cracking in welds by GTAW was considerably decreased as compared with that of SMAW. And cracks were well generated in the Inconel 690 overlay welds adjacent to 575 309L welds. This means that the hot cracking susceptibility of Inconel 690 welds was largely varied by chemical components and/or compositions of filter metals, base metals and neighboring welds.

• Journal of Welding and Joining
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• 제25권5호
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• pp.58-63
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• 2007

The relationship between GMA welding conditions and the bead shape of overlay weld was studied by using ${\Phi}1.6mm$ hypo-eutectic metal-cored wire designed for hardfacing against the severe metal-to-metal wear. As the welding voltage increased, the dilution also increased but the sudden drop of dilution was observed at $30{\sim}33V$. It was considered to be due to the decrease of penetration resulting from the change of transfer mode, from short circuit to spray. It was also found that the behavior of penetration with welding current was dependant on the transfer mode. The short circuit mode exerted the penetration to decrease while the spray mode did it to increase with increase of welding current. The former was considered to be responsible for the remarkable decrease in dilution at low welding voltage region. The change of transfer mode also had an effect on the behavior of bead width with welding current but it did not on the bead spreadability defined as W/H ratio. It was considered that the optimal welding conditions for multi-pass overlay welding could be obtained from the bead spreadability suitable for bead lapping and the dilution as low as possible in the spray transfer mode.

• Journal of Welding and Joining
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• 제15권6호
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• pp.96-104
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• 1997

The present study was aimed to correlate the microstructure and the hardness as well as the wear resistance of the metal-ceramic particulated composite layer on the pure Al plate. The composite layers were constructed by the addition of TiC particles on the surface of Al-Cu alloyed layers by PTA overlaying process. Initially, the Al-Cu alloyed layers were achieved by the deposition of Al-(25 ~ 48%) Cu alloys on the pure Al plate by TIG process. It was revealed that TiC particles were uniformly dispersed without any reaction with matrix in the composite layer. The volume fraction of TiC particles (TiC V F) increased from 12% to 55% with increasing the number of pass of composite layer. Hardnesses of (Al-48%Cu + TiC (3&4layers)) composite layer were Hv450 and Hv560, respectively, due to the increase of TiC V/F. Hardnesses of (Al-Cu + TiC) composite layers decreased gradually with insreasing temperature from 100$^{\circ}$C to 400$^{\circ}$C, and hardnesses at 400$^{\circ}$C were then reached to 1/5 - 1/10 of room temperature hardness depending on the construction of composite layers. The Specific wear of (Al + Tic) layer and Al-48%Cu alloyed layer decreased to 1/10 of the of pure Al, while the specific wear of (Al-48%Cu + TiC (4 layers)) composite layer exhibited 1/15 of that of steel such as SS400 and STS304.

• 한국초지조사료학회지
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• 제18권3호
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• pp.171-178
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• 1998

우리나라 중서부 천결지에서 많이 자생하는 바다 새를 사료작물화 할 수 있는지를 구명하기 위하여 채종후 저장조건, 광, 옹도, 당수깊이, 염농도 및 복토깊이가 바다새의 종자 발아에 미치는 영향을 조사하였던 바, 그 결과를 요약하면 다음과 같다. 1. 바다새 종자의 발아특성은 광의 유무 간에는 유의성이 없었으며, 광의 유무 보다는 채종후 저장 조건이 유의성이 컸고, 광과 저장조건 상호간에도 유의성이 없었다. 2. 바다새의 발아율, 평균발아일수, 발아세 및 발아계수에 대한 발아온도 효과는 환온조건 보다는 변온조건에서 양호하였고, 환온조건에서는 $35^{\circ}C$에서 환온조건에서는 $35/25^{\circ}C$에서 가장 우수하게 나타났다. 3. 담수 깊이별 바다새의 발아율, 평균발아일수, 발아세 및 발아계수는 처리 수준간 통계적 유의성이 커서 담수 깊이가 Ocm인 구에서 제일 좋았으며, 담수 깊이가 0.5cm에서 1cm로 담수 깊이가 깊어 질수록 발아율이 현저히 떨어졌고 3cm 이상 담수서는 전혀 발아가 되지 않았다. 4. 고농도형 바다새의 발아율, 평균발아일수, 발아세 및 발아계수는 처리 수준간 유의성이 커서 고농도 0.2%일 때가 발아가 제일 좋았고 고농도가 높아질수록 발아율이 떨어졌으나 고농도 1%에서도 30% 이상의 발아율을 보여 내염성이 높음을 알 수 있었다. 5. 바다새 종자의 복사 수준별 발아율, 평균발아일수, 발아세 및 발아계수는 처리 수준간 유의성이 커서 복사 깊이가 0.2cm일 때가 제일 좋았고 복사 깊이가 깊어질수록 발아특성이 떨어져 복토 깊이가 1cm 이상에서는 거의 발아가 되지 않았다.5회 예취구가 37.06%로 유의하게 낮았고 3회와 4glh 예취구에서는 각각 40.27과 40.53%를 나타내어 유의성이 인정되지 않았다. 6. 건물 생산효율은 3회와 5회 예취구의 30kg N/ha/cut 수준에서 18.9kg와 15.7kg을 나타내어 가장 높았고, 4회 예취구에서는 90kg N/ha/cut 수준에서 16.3kg으로 가장 높았다. 전 질소량은 예취번초별로 3회 예취구에서는 90kg N/ha/cut수준에서 0.52kg, 4회와 5회 예취구에서는 30kg N/ha/cut수준에에서 각각 0.51kg과 0.43kg의 높은 전 질소량을 나타내었다. 7. 경제적 액상구비 시용수준의 범위는 3회 예취구에서 107.2~151.0kg N/ha/cut, 4회 예취구에서 359.1~375.7kg N/ha그리고 5회 예취구에서 160.3~236.9kg N/ha이었으며, 이 때 얻어지는 경제적 한계수량은 각각 9.6~10.0ton/ha, 12.4~12.6 ton/ha 및 9.0~9.7 ton/ha의 범위를 나타내었다. 8. 액상구비의 시용수준에 따른 액상구비의 한계시용수준은 3회 예취구에서 420.0kg/ha, 4회 예취구에서 440.6kg/ha, 그리고 5회 예취구에서 666.3kg/ha로 추정되었다.례, 오버레이 용접기술 및 용접재료의 개발현황 둥을 중심으로 살펴봄으로서 아직 국내에서는 널리 알려지지 않은 본 기 술의 활용을 넓이고자 한다. within minimum time from beginning of the shutdown.및 12.36%, $101{\sim}200$일의 경우 12.78% 및 12.44%, 201일 이상의 경우 13.