• 기술혁신학회지
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• 제7권1호
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• pp.159-181
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• 2004

본 연구에서는 신차개발 과정에서 공급업체의 조기참여 프로그램을 통한 자동차용 강판 제조업체의 기술혁신에 대해 고려하기로 한다. 먼저, 치열한 경쟁 하에 놓인 자동차용 강판 공급업체의 생존전략으로 자동차업체와의 기술적 파트너십의 중요성과 함께 시장을 둘러싼 대내외 경영환경을 분석하고자 한다. 자동차산업의 신차개발 프로세스 단계별 기술적 목표를 명확히 제시하고 차체의 수명사이클에 근거한 최적 소재를 선정하기 위한 조기참여 활동의 필요성을 강조하고자 한다. 또한 자동차용 강판 공급업체의 최적 기술전략 수립 및 방향을 설정하기 위해 자동차용 소재시장에서의 철강재 위상을 제고하고, 핵심 기술목표를 도출하고자 한다. 마지막으로 자동차용 강판 제조업체의 핵심 기술로 고성형성, 고강도강판 및 내식성이 우수한 도금강판에 대해 공급업체의 조기 참여를 통한 기술혁신 과정을 살펴보고자 한다.

• 소성∙가공
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• 제27권3호
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• pp.145-153
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• 2018

Magnesium material could be widely used in the automotive industry because of its high strength to weight ratio, but the electric resistance spot welding process of magnesium sheets is difficult because of its low electric resistance and high thermal conduction and thermal expansion. For this reason, an electric resistance surface friction spot welding process using rotating dies is suggested for the spot welding of magnesium metal sheets. This welding method can be characterized by three heating methods: (1) electric resistance heating on contacted surface, (2) surface friction heating by rotating dies, and (3) thermal conduction heating from heated steel electrodes, for the fusion of metal at the interfacial zone between the two magnesium sheets. This welding process also has variables to explore, such as welding currents, diameters of the steel electrode, and rotating dies. It was found that the welding strength could reach industrial requirements by applying a welding current of 11.0kA, with steel electrodes of 12mm diameter, with rotating dies of 4.4 mm diameter, under the condition of a revolution speed of 1200rpm of rotating dies, for the surface friction spot welding process of AZ31 magnesium alloy sheets of 1.4mm thickness.

• Corrosion Science and Technology
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• 제10권2호
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• pp.47-51
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• 2011

Main issues in the automotive industry are the reduction of vehicle body weight for energy savings and improvement of crashworthiness for passenger safety. In order to address both these issues, there has recently been increasing application of galvannealed advance high strength steel (GA AHSS) sheets for automobiles. However, GA AHSS sheets have some surface defects such as coating bare spots due to the addition of solid-solution strengthening elements, which result in the deterioration of the galvannealing reaction. In this study, the effects of galvannealed manufacturing conditions on surface and mechanical properties, resistance spot weldability on a laboratory scale, and GA 980 MPa steel sheets produced by commercial continuous galvannealing line (CGL) were investigated.

• 대한금속재료학회지
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• 제46권11호
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• pp.713-724
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• 2008

The need to lower the weights of automotive vehicle and to improve the safety of cars has resulted in the development of high strength steels such as TRIP(Transformation Induced Plasticity) and DP (Dual Phase) steel. It is well known that the higher strength of steel shows the poorer press formability. Among the high strength steels, DP steel shows several good characteristics such as low yield ratio, high initial n value, high elongation, high bake hardenability and anti-aging property. However, there's a certain limit in application of DP steels to the automotive panel parts because their poor deep drawbility caused by martensite. In this study, the effect of alloying elements on the deep drawability and recrystallization texture in TS 440MPa grade DP steel with 0.015~0.02% carbon has been investigated on the base of SEM, TEM, XRD and EBSD analysis.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1997년도 특별강연 및 추계학술발표 개요집
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• pp.172-175
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• 1997

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2003년도 추계학술발표회초록집
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• pp.141-141
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• 2003

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 제5회 압연심포지엄 신 시장 개척을 위한 압연기술
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• pp.45-52
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• 2004

Continuing pressure for the weight reduction of vehicles and improvement of collision safety is driving the development of new high strength steel with excellent formability. The formable high strength steels which have excellent drawability have been developed and applied to the complicated inner panels. Although BH steel have mainly occupied the material market for outer panels, it is challenged by DP steel which have low yield strength and good bake hardenability. The advanced high strength steel, TRIP steels and DP steels which have excellent formability are new alternatives to conventional HSLA steel for structural parts such as members and pillars. HSLA steels also have been used for automotive bumper reinforcements due to their high yield ratio. Higher grade complex phase steel(CP) were developed for bumper reinforcements by addition of precipitation hardening to transformation strengthened steel. The usage of the advanced high strength steel ale increasing and will become the main material in structural parts near future. This paper describes the features of newly developed high strength cold rolled steels for automobiles.

• 대한금속재료학회지
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• 제49권11호
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• pp.831-838
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• 2011

Effects of spangle size and crystallographic characteristics on the surface appearance, galling properties, and adhesive strength of hot-dip galvanized steel sheets have been investigated. Both spangle size and crystallographic orientation measured by optical microscopy, scanning electron microscopy, and X-ray diffraction were identified as critical factors influencing the galvanized coating performance. By decreasing the spangle size, surface appearance and galling properties related to the friction coefficient were significantly improved. However, low temperature adhesive-strength with small spangle galvanized steel sheets showed lower values compared to commercially used galvanized coating. The variation of adhesive strength in terms of spangle size has been clarified.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.176-180
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• 1996

Continuous wave CO$_{2}$laser beam welding and formability of zinc coated steel shets were investigated. First, optimal welding condition could be obtained in but welding by using the data for heat input and welding velocity. The highest value of Erichsen test is 79.3% compare to that of base matel. Secondly, Formability of laser welds was investigated by using ball punch tester. Finally, the forming results of butt-welded sheets showed that the joing design was important to apply the laser welded blank in the automotive production.

• Journal of Welding and Joining
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• 제27권3호
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• pp.38-43
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• 2009

The optimization of the welding parameters was studied to maximize the weldability and minimize the amount of spatter in the MAG welding of automotive steel sheets under different shielding gas composition ratio. JS-EFSC, JS-SPHC steel plates and Ar mixture gases were used as a substrate and shielding gas for welding respectively. The five welding parameters were selected through preliminary experiments and their effects on the weldability were analyzed. Experiments were performed using the Taguchi experimental method. As results, appropriate range for welding could be achieved. Amount of spatter in 80%Ar+20%$CO_2$ shielding gas was 20% of that of $CO_2$welding. Therefore, in terms of high productivity and welding cost, Ar mixture gas(80%Ar+20%$CO_2$) was recommended as a shielding gas for application of MAG process, indicating the low spatter and good weld quality.