• 제목/요약/키워드: AHSS

검색결과 56건 처리시간 0.025초

초고강도강판 마찰특성의 실험적 규명 (Experimental Determination of Friction Characteristics for Advanced High Strength Steel Sheets)

  • 김남진;금영탁
    • 소성∙가공
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    • 제22권4호
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    • pp.223-228
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    • 2013
  • The friction coefficients of advanced high strength steel sheets were experimentally determined. In the friction test, the pulling and holding forces acting on the sheet for various friction conditions, such as lubricant viscosity, pulling speed, blank holding pressure, sheet surface roughness, and hardness of the sheet were measured and the friction coefficient was calculated based on Coulomb's friction law. While the friction coefficient, generally, decreases as the value of friction factor increases, the factor associated with the sheet surface roughness shows U shape behavior for the friction coefficient. Furthermore, the relationship between friction coefficient and the wear volume, which was computed for the roughness of both sheet surfaces and the friction area, is linearly proportional.

분리형 섕크를 갖는 SPR의 형상 설계를 위한 유한요소해석 (Finite Element Analysis for Design of Divided Shank of Self-Piercing Rivet)

  • 김관우;김동범;조해용
    • Journal of Welding and Joining
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    • 제34권2호
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    • pp.54-58
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    • 2016
  • SPR(Self-Piercing rivet) is mechanical element of joining sheet metal components without the need for pre-punched or pre-drilled holes. Newly designed SPR is developed for high joining strength and shearing strength than semi-tubular rivet. In this study, divided shank of self-piercing rivet were designed for joining DP440 and SILAFONT. Newly designed SPR was simulated by using FEM code DEFORM-3D. In simulations of SPR process, various shape of self-piercing rivet were considered for semi-tubular and newly designed SPR. In other to examine the joinability, joining load and lap-shear load of newly designed SPR were compared with semi-tubular by simulated results and experimental ones.

Development of Al-added High Strength Galvannealed Daul Phase Steel Sheets

  • Kim, Dong-Eun;Han, Young-Chul;Ko, Heung Seok;Kim, Jong-Gi;Moon, Man-Been
    • Corrosion Science and Technology
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    • 제10권5호
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    • pp.162-166
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    • 2011
  • Effects of chemical compositions and manufacturing conditions on mechanical properties and microstructures were investigated in order to obtain galvannealed high strength dual phase steel sheets with superior mechanical properties and coating properties. An intercritical annealing between Ac1 and Ac3 was conducted to produce the DP (dual phase) steel sheets, followed by quenching to room temperature. The purposes of Al addition are to reduce the iron oxidation with chemical composition (Si, Mn etc.) and to improve the wettability by liquid zinc. The present study will focus on the characterization for making dual phase steel sheets and enhancing the galvanizability of Al added DP steel sheets about continuous annealing line in CGL.

시뮬레이션을 이용한 780MPa급 강재의 판재 조합에 따른 저항 점 용접의 로브곡선 특성 분석 (Lobe Curve Characteristic Analysis of Resistance Spot Welding for Sheet Combination of 780MPa Steel Sheet Using Simulation)

  • 손창석;박영환
    • Journal of Welding and Joining
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    • 제30권6호
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    • pp.68-73
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    • 2012
  • Nowadays, car manufacturers tried to improve automotive fuel efficiency, and applied many high strength steels such as AHSS or UHSS to car bodies. Therefore, the number of steel combinations for the resistance spot welding are dramatically increased and the need for weldability evaluation of these combinations are also required. In this study, we suggest the lobe curve using FEM simulations for DP780 steel with 1.0t, 1.4t. The lobe curves which could expressed weldablity and optimal welding condition were obtained according to 6 steel combinations. There were two combinations for same steel sheet which were DP780 1.0t, DP780 1.4t. Dissimilar steel sheet combination with different thickness was 1.0t and 1.4t of DP780. Different steel combinations were DP780 1.0t and SPRC440 1.0t, and DP780 1.0t and DP590 1.0t. Finally dissimilar combinations was and DP780 1.0t and DP590 1.4t. The trend of low boundary and high boundary variation of lobe curve were analyzed with a viewpoint of the contact resistance and the heat input.

알루미늄 기반 Advanced Multi-Material 기술의 선진 동향 (Trends of Advanced Multi-Material Technology for Light Materials based on Aluminum)

  • 이목영;정성훈
    • Journal of Welding and Joining
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    • 제34권5호
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    • pp.19-25
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    • 2016
  • Global warming is hot issue to keep the earth everlastingly. Despite the increase of the world population and the energy demand, the world oil supply and the oil price are hold the steady state. If we are not decrease the world population and the energy consumption, unforeseeable energy crisis will come in the immediate future. AMT acronym of Advanced Materials for Transportation is a non-profitable IEA-affiliated organization to mitigate the oil consumption and the environment contamination for the transportation. In recent, Annex X Multi-materials Joining was added to enhance the car body weight reduction cause the high fuel efficiency and the low emission of exhaust gas. Multi-materials are the advanced materials application technology to optimize the weight, the performance and the cost with the combination of different materials such as Al-alloy, Mg- alloy, AHSS and CFRP. In this study, the trends of AMT strategy and Al-alloy based multi-materials joining technology were review. Also several technologies for Al-alloy dissimilar joining were investigated.

박판성형가공을 고려한 자동차 충돌해석 (Crash Analysis of the ULSAB-AVC Model with Considering Forming Effects)

  • 허훈;윤종헌;바오이동;김세호;박성호
    • 소성∙가공
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    • 제15권8호
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    • pp.556-561
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    • 2006
  • Most of auto-body members are composed of stamping parts. These parts have the non-uniform thickness and plastic work hardening distribution during the forming process. This paper is concerned with the side impact analysis of the ULSAB-AVC model according to the US-SINCAP in order to compare the crashworthiness between the model with and without considering the forming effect. The forming effect is ca]ciliated by one-step forming analysis for several members. The crashworthiness is investigated by comparing the deformed shape of the cabin room the energy absorption characteristics and the intrusion velocity of a car. The result of the crash analysis demonstrates that the crash mode, the load-carrying capacity and energy absorption can be affected by the forming effect. It is noted that the design of an autobody should be carried out considering the forming effect for accurate assessment of crashworthiness.

440MPa 급 도금, 비도금 강판의 Pulse GMA 용접성 평가 (Pulse GMA weldability evaluation for 440MPa coated and uncoated steel)

  • 소우주;김동철;강문진
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2010년도 춘계학술발표대회 초록집
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    • pp.67-67
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    • 2010
  • 최근 전 세계적으로 유가상승 및 환경에 대한 관심이 증대되면서 자동차 업계에서는 차량 경량화를 통한 연비향상에 대한 연구가 활발히 진행되고 있다. 대표적인 차량 경량화 방법으로 초경량 철강 차체의 개발을 들 수 있는데 이는 고강도강을 차체에 적용함으로써 강성을 증대시킴과 동시에 두께 감소에 의한 경량화를 이루는 방법이다. 하지만 고강도강은 자체의 높은 강성을 지니는 반면 첨가된 합금원소에 의하여 용접성이 떨어지는 제약을 가지고 있다. 펄스 GMA 용접은 One Drop Per Pulse (ODPP) 의 안정된 용적 이행으로 스패터 발생이 거의 없으며 일반 GMA 용접에 비하여 용접성이 우수하여 자동차 차체 조립공정에 적용되고 있다. 본 연구에서는 440MPa 급 도금, 비도금 강판 및 이종 강판의 겹치기 용접 실험을 통해 강종별, 두께별 펄스 아크 용접에 대한 용접성 평가 및 데이터 베이스를 구축하고자 하였다. 용접부 단면마크로, 인장시험, 경도시험을 통해 적정 용접영역을 확보하였으머, 고속카메라 촬영을 통해 보호가스에 따른 용적 이행 현상을 확인하였다.

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자동차 초고강도 강판 패널의 스프링백 저감에 관한 연구 (Study on the Springback Reduction of Automotive Advanced High Strength Steel Panel)

  • 김병규;이인석;금영탁
    • 소성∙가공
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    • 제18권6호
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    • pp.488-493
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    • 2009
  • The very big springback of advanced high strength steel(AHSS) sheets invokes undesired shape defects, which can be generally eliminated by die correction or process parameter control. The springback reduction by controlling the forming process parameters is easy for the application, but limited for the bulky achievement. In this study, the effective die correction method, which obtains the modification of tool shape from the relationship between die design variable and springback, is introduced and is applied to the TWB tool of automotive side rail to show the validity and usefulness. Among the die correction trials repeatedly performed, the first trial is carried out by correcting the tool shape to the opposite direction to the springbacks of several tool sections. Next trials are done by extrapolating the springbacks of among the original tool uncorrected and the tools corrected negative amounts of the springback and by finding tool shapes without springbacks. After the angle of side wall and radius of curvature of horizontal bottom floor are chosen as design variables in the tool design of side rail, the tool shape is corrected 3 times. The accuracy of final shape within the assembly limit of 1mm and the springback reduction of 75.8% compared to the uncorrected tool are achieved.

마찰교반접합공정을 적용하여 겹치기 접합을 실시한 복합조직강의 미세조직과 기계적 특성

  • 김상혁;이광진;우기도
    • 한국재료학회:학술대회논문집
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    • 한국재료학회 2012년도 춘계학술발표대회
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    • pp.103.1-103.1
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    • 2012
  • 본 연구는 차량경량화를 위하여 높은 인장강도와 우수한 인성을 가지는 590MPa급 이상조직강(Dual phase steel)을 이용하여 1991년 TWI(The Welding Institute)에서 개발된 마찰교반접합을 적용하여 접합을 실시하였다. 접합의 공정조건으로 툴의 회전속도는 250~350 RPM, 접합속도로는 50~350 mm/min로 겹치기접합을 실시하였다. 접합에서 사용된 툴은 Megastir에서 제작한 고융점마찰교반접합용 툴인 PCBN(Q-60)을 이용하였고 연구에 사용된 DP590은 포스코(POSCO)에서 제작된 1.4t(mm) 두께인 AHSS(advanced high strength steels)을 사용하였다. 모재인 DP590과 접합체의 미세조직은 광학현미경과 주사전자현미경을 이용하여 관찰하였으며 기계적 특성은 경도시험과 인장시험을 실시하여 조사하였다. 경도의 분포는 모재에서 약 220~230Hv이며 TMAZ부분에서 상승하기 시작하여 접합부에서 약 320Hv까지 상승하는 경향을 보였으며 인장시험 결과 접합속도 100~200 mm/min에서는 모든 시편이 모재에서 파단되어지는 것을 확인할 수 있었다. 위와 같은 결과 300~350 RPM, 100~200 mm/min의 공정조건에서는 접합이 성공적으로 이루어졌으며 차량경량화에 적용이 가능하다고 판단되어진다.

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Corrosion Resistance of Mg-Added Galvannealed Steel Sheets with Nano-Composite Coating

  • Jo, Du-Hwan;Yun, Sang-Man;Paik, Doo-Jin;Kim, Myung-Soo;Hong, Moon-Hi
    • Corrosion Science and Technology
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    • 제19권2호
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    • pp.57-65
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    • 2020
  • As competition among global automakers intensifies, demand for materials that are better in price and performance is increasing. While steel and plastic materials compete for automotive fuel tanks, plastic materials have advantages such as light weight for automobiles. However, they have high prices. Accordingly, in this paper, four types of Zn-X plated steel sheets, electroplating (X = none, Sn) and galvannealed (X = Fe, Fe-Mg), were manufactured and their applicability as a fuel tank material was evaluated. Nano-composite coating solution with good conductivity was treated on the surface of plated steels using a roll coater and then cured through induction furnace to improve corrosion resistance. Quality characteristics such as corrosion resistance, fuel resistance to diverse gasoline and diesel fuels, and seam weldability were evaluated for the above plated steels. Their properties were compared and analyzed with conventional Zn-Ni electroplating steels. Among the above plated steels, Zn-Fe-Mg galvannealed steels coated with nano-composite coating exhibited better properties than other steels. Detailed experimental results suggest that evenly distributed Mg elements on the coating layer play a key role in the enhanced quality performance.