• Journal of Welding and Joining
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• 제11권4호
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• pp.79-90
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• 1993

Shielded metal arc welding, one-ploe and two-pole submerged arc welding were accomplished to investigate microstructure changes on phase transformation behavior in $60kg/mm^2$ quenched and tempered high strength steel. Microstructures were examined by optical micrograph and TEM. In shielded metal arc welding (oxygen 250ppm), the inclusions were small size (0.3-0.5$\mu\textrm{m}$)and small in number. In submerged arc welding (oxygen 430-529ppm), the inclusions were larger(0.7-2$\mu\textrm{m}$) than that of shielded metal arc welding and large in number. Microstructure mainly depends on number and distribution of inclusions in fusion zone of weld metal. It was noticed that a limited number of inclusions favors the formation of acicular ferrite.

• Journal of Welding and Joining
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• 제23권1호
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• pp.77-85
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• 2005

The structures and mechanical properties of friction stirred welds of oxygen free copper(OFC) sheet were investigated. Defect-free welds were obtained in a relatively wide range of the welding conditions from 1000 to 2000 rpm, and welding speed from 500 to 2000 mm/min. The microstructure of the stirred zone(SZ) showed recrystallized grains, and the gram size varied largely with the welding conditions. The SZ hardness values including those of all the optimum welding conditions were slightly lower than that of the base metal, and increased with decreasing heat input. The tensile strength of the all-SZ increased with increasing the hardness values. The Hall-Fetch relationship was confirmed between the yield strength of the all-52 and the recrystallized grain size of the SZ.

• Journal of Welding and Joining
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• 제16권2호
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• pp.93-99
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• 1998

The effects of welding conditions of gas metal arc welding on the elements loss of solid wire, oxygen content and impact toughness of weld metals were studied. Deoxidizing elements loss was increased with increase of arc voltage in both short-circuit transfer mode and globular transfer mode. It is believed that increase of arc voltage results in increase of reaction time between elements in the droplet and surrounding gas at the end of wire and in the arc column. Based on the thermodynamic equilibrium model, the oxygen content of weld metal can be predicted with the content of silicon and manganese as following : [%O] = $K([%Si][%Mn])^{-0.25}$, K = -15518/T+6.01. The equilibrium temperature was dependent on shielding gas, and it was 187$0^{\circ}C$ for $CO_2$ gas and 180$0^{\circ}C$ for 20%$CO_2$-80%Ar gas. The oxygen content of weld metal which shows maximum impact toughness was varied with deoxidizing alloy system of wires, 0.041 wt% for Si-Mn type wire and 0.026 wt% for Si-Mn-Ti type wire.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 제5회 압연심포지엄 신 시장 개척을 위한 압연기술
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• pp.240-248
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• 2004

Recently, the customer's demands for automotive steel sheet have been diversified and sterned more. Therefore, as the tendency of auto industry light-weight, one among these requirements is the trend for high strength together with the thinness of automotive steel sheet. Because Mn added essentially in producing high strength steel sheet is bonded strongly with oxygen, the Fine oxidation layer was created at the welding face after the flash butt welding operated in entry section of pickling line. Thereby it was caused the crack or breakage of welding part in process of cold rolling. At this research, in order to protect the contact Mn with oxygen in atomosphere it was considered to fire oxygen with LNG and the related researches have been gone forward with the find out concrete and to apply them to operation.

• Journal of Welding and Joining
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• 제5권3호
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• pp.38-45
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• 1987

An investigation was conducted to find out the factors influencing on the impact toughness of austenitic-and duplex stainless steel weld metal. Various welding process with commerically available consumables was adopted to get weld doposited metal. The oxygen content of each weld metal was very sensitiive to welding process, involving flux composition, shielding gas and structural features. The results of this study show tat the content of oxygen as an oxide inclusion significantly affects impact toughness, and .delta.-ferrite distribution is also correlated with resultant toughness value.

• 한국화재소방학회논문지
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• 제15권2호
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• pp.53-58
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• 2001

본 연구에서는 조선 및 화학공장 등 산업현장에서 용접·용단작업 공정에서 비산 되는 불티에 의한 화재 예방을 위하여 불티 차단막에 관한 방염 및 난연 성능 평가를 실시하였다. 방염성능 실험결과 기존제품의 용접불티 차단막 6종 모두 충분한 방염성능을 갖고 있었다. 그러나, 용접·용단 불꽃에 의한 난연성 실험 결과 섬유유리에 수지코팅한 제품 2종은 용접·용단 불티에 대한 화재예방성능이 부족한 것으로 나타났다. 용접 불티 차단막의 최소산소지수의 국내기준은 30이상으로 고려하는 것이 좋을 것으로 사료된다. 용접 불티 차단막의 성능향상을 위한 제속적인 연구가 필요하며, 방염 및 난연성능 기술지침 개발의 기초자료로서 활용될 수 있을 것으로 사료된다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2003년도 춘계학술발표대회 개요집
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• pp.231-233
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• 2003

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.225-227
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• 2002

Recently, there are many researches in several places for a new resource, ahead. Also, Water of $70\%$ in the earth it is interested and studied by around world. Long ago, in the side processing-use, it is making study the welding of Hydrogen- oxygen Gas, which is burned to acquired it(hydrogen+oxygen) by electric-disintegration into water, which has perfect-burning rather than exhaust carbon and it has excellent-sides in financials and efficiencies than existing-gas welding by sparking-characteristics of Hydrogen Oxygen gas. Therefore, with constant current source, it is intended to make a producing gas ratio through designing and making for the use of SCR rectifier of existing-formula and then in this paper it hopefully is coming up to characteristics of welding machine and producer of hydrogen oxygen gas with current-controlled type.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1997년도 특별강연 및 춘계학술발표 개요집
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• pp.204-210
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• 1997

• Journal of Welding and Joining
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• 제27권5호
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• pp.55-61
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• 2009

Pure titanium and its alloys have good formability, excellent corrosion resistance and high strength to weight ratios. Therefore, it has been using to heat exchangers, offshore plants, sports equipments, and etc. As broad as its application fields, it also increases welding locations. Conventional GTAW and GMAW are very popular welding methods of titanium, but it has a high heat input and wide HAZ. It has a possibility of inducing Stress Corrosion Cracking. So, laser welding method has been using to get reliable welds by reducing heat input. Weld beads change its color to silver, gold, brown, blue, and gray by shied conditions. And the closer to gray, the more oxidize, nitride and embrittlement. The most effective atom to embrittlement was nitrogen. And shield gas flow was not so effective over the constant flow rates. In this study, weld properties of the pure titanium were investigated by pulsed & CW Nd:YAG lasers and evaluated by various shield conditions. And It is observed that nitrogen is more effective to oxidation and embrittlement of titanium compared with oxygen by oxygen and nitrogen quantitative analysis.