한국해양대학교

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LPG특수선 재액화장치용 순티타늄판의 Nd:YAG 레이저 용접성에 관한 연구

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dc.contributor.author 곽명섭 -
dc.date.accessioned 2017-02-22T02:23:38Z -
dc.date.available 2017-02-22T02:23:38Z -
dc.date.issued 2008 -
dc.date.submitted 2008-07-30 -
dc.identifier.uri http://kmou.dcollection.net/jsp/common/DcLoOrgPer.jsp?sItemId=000002174326 ko_KR
dc.identifier.uri http://repository.kmou.ac.kr/handle/2014.oak/8327 -
dc.description.abstract Titanium and its alloys have excellent corrosion and erosion resistance, high specific strength and creep properties in high temperature, and these properties make them using various fields of application. For example, the chemical plant, sports and leisure equipments, aero spaces, and so on. Titanium heals itself even though the oxidation layer(TiO2) is broken in the sea water. Therefore, it has outstanding resistance for the stress corrosion cracking, crevice corrosion, pitting and microbiologically influenced corrosion. Additionally, pure titanium has good formability which bring out to the best material for the heat exchanger plate. Conventional plate type heat exchanger has prevented fluid leakage with gaskets between the plates by mechanical joining method, but gaskets are hardened in high temperature and pressure. Thus, LPG re-condenser which is always in high temperature and pressure, is jointed its plates by welding. EBW and diffusion bonding make high quality welds, but it should be done in vacuum conditions. And arc weldment has large HAZ and possibility of distortion because of large heat input. Hence, laser welding is applied to get sound beads with small heat input and high aspect ratio in the air. CP titanium(ASTM grade 1) was used by experimental materials. It was welded by pulsed and CW Nd:YAG laser. The best welding conditions for production were drew out after investigation of welding parameters and heat sources. The principal laser welding factors for titanium are as followed -
dc.description.abstract First, the pulse width which can control the peak power is the most important parameters of pulsed laser. And the laser power and welding speed that can control the heat input are the most important parameters in CW laser. Secondly, the weld bead changes its color to gold, brown, blue and gray with oxidation. And nitrogen is more effective to the embrittlement of welds than oxygen. Finally, if weldments are exposed in the air, microstructure of weld metal is changed to martensitic structure. Conclusionally, the most important thing for titanium welding is the selection of shield conditions. -
dc.description.tableofcontents Abstract 1. 서론 1 1.1 연구 배경 1 1.2 연구 목적 및 내용 4 2. 이론적 배경 6 2.1 티타늄의 종류와 특성 6 2.1.1 티타늄의 종류 6 2.1.2 티타늄의 특성 9 2.2 티타늄의 제조방법 및 적용현황 19 2.2.1 티타늄의 제조방법 19 2.2.2 티타늄의 적용현황 22 2.3 티타늄의 접합기술 25 2.3.1 접합 방법에 따른 분류 25 2.3.2 용접 금속에 따른 분류 30 3. 실험 재료 및 방법 34 3.1 실험 재료 34 3.2 실험 장치 및 방법 36 3.2.1 Nd:YAG 레이저 36 3.2.2 실험 방법 41 4. 실험 결과 및 고찰 44 4.1 순티타늄의 펄스 Nd:YAG 레이저 용접특성 44 4.1.1 겹치기용접 44 4.1.2 엣지용접 75 4.2 순티타늄의 연속 Nd:YAG 레이저 용접특성 86 4.2.1 비드용접 86 4.2.2 겹치기용접 94 4.2.3 엣지용접 102 4.3 실드조건이 용접특성에 미치는 영향 114 4.3.1 비드색깔 변화에 따른 용접성 114 4.3.2 미세조직에 미치는 영향 120 4.3.3 적절한 실드범위의 지정 127 4.4 용접부의 기계적 특성 평가와 재액화장치로의 적용 130 4.4.1 경도 특성 130 4.4.2 인장 특성 136 4.4.3 실물 열교환판으로의 적용 140 5. 결론 144 참고문헌 146 -
dc.language kor -
dc.publisher 한국해양대학교 대학원 -
dc.title LPG특수선 재액화장치용 순티타늄판의 Nd:YAG 레이저 용접성에 관한 연구 -
dc.title.alternative A Study on the Weldability of Pure Titanium Sheet for LPG Reliquifaction System by Nd:YAG Laser -
dc.type Thesis -
dc.date.awarded 2008-08 -
dc.contributor.alternativeName Myung-Sub Kwak -
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재료공학과 > Thesis
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