• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.12
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• pp.1367-1372
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• 2014

As the awareness of the environmental crisis has recently increased around the world, numerous studies in the transport industry have been conducted to solve this problem through lightweight car bodies. The hot-stamping process has been presented as solution to achieve a light weight. Hot-stamping is a method that is used to obtain ultra-high strength steel (1,500 MPa or greater) by simultaneously forming and cooling boron steel in a press die after heating it to a temperature of $900^{\circ}C$ or above. This study involved a, fundamental examination of laser parameters to investigate the laser weldability of boron steel. As a result, the following optimum parameters for the shielding gas were found: Q = 20 l/min, ${\alpha}=40^{\circ}$, d = 20mm, and l = 0 mm. The hardness of butt weldment increasesed sharply as a result of martensite formation at the fusion zone.

• Transactions of Materials Processing
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• v.32 no.3
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• pp.160-165
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• 2023

As the supply of eco-friendly vehicles increases, the application rate of hot stamping components is rising to reduce vehicle weight and improve safety. Although Al-Si coated steel sheets are commonly used in hot stamping processes, their manufacturing costs are elevated due to process patents and royalties. Various hot stamping studies have been conducted to reduce these production costs. In this study, we derived a process control method for suppressing the oxide layer of hot stamping parts using uncoated boron steel sheets. Firstly, hat-shaped parts were hot stamped under atmospheric conditions to analyze the tendency of oxide layer formation by location. Then, the Gleeble system was used to observe oxide layer formation based on oxygen content under various atmospheric conditions. Finally, the oxide layer thickness was quantitatively measured using SEM images.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.113-113
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• 2009

세계적으로 환경문제에 대한 관심이 커짐에 따라 연료 효율 향상과 매연을 줄이기 위해 차량 경량화 요구가 증가하는 동시에 안전 규제가 강화되고 있어 높은 강도를 가지는 소재의 적용이 증가하고 있다. 충돌 시 차량 구조를 유지시켜주는 범퍼나 B-필러와 같은 부품에 1500MPa급의 초고강도강이 적용되고 있으며 레이저 용접이 가지는 장점이 많이 알려지면서 그 사용이 증가하는 추세이다. 따라서 레이저 용접에 의한 초고강도강의 용접 특성에 대한 연구가 필요하다. 본 연구에서는 1500MPa급 초고강도강의 레이저 맞대기 용접을 실시하여 단면, 경도 측정, 인장시험을 통해 용접부 특성을 파악하였다. 파이버 레이저와 디스크 레이저를 사용하여 각각의 레이저빔 직경 변화에 따른 입열량 변화에 따라 용접성에 미치는 영향에 대해 알아보았다.

• Transactions of Materials Processing
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• v.18 no.4
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• pp.304-309
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• 2009

Quenchable boron steel is a new type of high strength steel to reduce the weight of automobiles and maintain the safety conditions. Quenchable blanks can be hot-stamped and hardened in a water-cooled tool to achieve high strength. In this paper, new alloy for hot stamping is designed based on requirement of mechanical properties and two types of surface coating are investigated in viewpoints of oxidization and exfoliation. An automotive part of center pillar is manufactured by hot-stamping using Al-Si coated sheet. The performance of developed part is compared by static compression test and side impact crash test.