Transactions of the Korean Society of Mechanical Engineers A (대한기계학회논문집A)

The Korean Society of Mechanical Engineers (대한기계학회)
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The Study on Weldability of Boron Steel and Hot-Stamped Steel by Using Laser Heat Source (II) - Laser Weldability of Hot Stamping Steel with Ultra-High Strength -

레이저 열원을 이용한 보론강 및 핫스탬핑강의 용접특성에 관한 연구 (II) - 초고강도 핫스탬핑강의 레이저 용접특성 -

  • Kim, Jong Do (Division of Marine Engineering, Korea Maritime and Ocean Univ.) ;
  • Choi, So Young (Division of Marine Engineering, Korea Maritime and Ocean Univ.) ;
  • Park, In Duck (Busan Laser Application Support Center, Korea Institute of Machinery & Materials)
  • 김종도 (한국해양대학교 기관공학부) ;
  • 최소영 (한국해양대학교 기관공학부) ;
  • 박인덕 (한국기계연구원 부산레이저기술지원센터)
  • Received : 2014.09.29
  • Accepted : 2014.10.13
  • Published : 2014.12.01
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Abstract

Hot-stamping is a method of obtaining ultrahigh-strength steel by simultaneously forming and cooling boron steel in a press die after it has been heated at $900^{\circ}C$ or above. After heat treatment, boron steel has a strength of 1500 MPa or more. This material ensures a high level of quality because it overcomes the spring-back phenomenon, which is a problem associated with high-strength steel materials, and the degree of dimensional precision is improved by 90 or more because of the good formability compared with existing types of steel. In this study, the welding characteristics were identified through the butt and lap welding of hot-stamped steel using a disk laser. Full penetration was obtained at a faster speed with butt welding compared to lap welding, and a white band was observed in every specimen.

핫스탬핑 공정은 고강도의 강을 얻을 수 있는 방법으로써, 일반적으로 보론강을 오스테나이트 온도까지 가열한 후, 성형과 냉각을 통해 제품을 생산한다. 열처리된 보론강은 1500MPa 이상의 강도를 가지기 때문에 경량화와 안전성을 동시에 향상시킬수 있는 특징이 있다. 뿐만아니라 우수한 성형성으로 인한 치수정밀도가 기존 강판대비 90 % 이상 향상되어 우수한 성형품질을 확보할 수 있는 장점도 있다. 따라서 본 연구에서는 디스크 레이저를 사용하여 핫스탬핑 강판의 맞대기 및 겹치기 용접을 실시하여 용접특성을 파악하였다. 실험결과, 맞대기 용접에서는 맞댄면의 갭에 영향으로 인해 겹치기 용접과 비교하여 더 빠른 속도에서도 완전 용입을 얻을 수 있었으며, 모든 용접부에서 열영향부에서 화이트밴드가 관찰되었다.

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References

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