Effect of YAG laser cutting on stretch-flangeability of ultra high strength TRIP sheet steel with bainitic ferrite matrix

Akihiko Nagasaka, Yuichi Kubota, Koh Ichi Sugimoto, Atsushi Mio, Tomohiko Hojo, Koichi Maku, Masahiro Kawajiri, Mitsunari Kitayama

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Effect of YAG laser cutting on stretch-flangeability of 0.2C-1.5Si-1.5Mn (mass%) ultra high-strength TRIP-aided sheet steel with bainitic ferrite matrix (TBF steel) having different martensite start temperatures, which were austempered at 375 or 450°C, was investigated for automotive applications. Hole notches of 5 mm diameter were produced by YAG laser cutting or mechanical punching for hole-expanding test. The stretch-flangeability was evaluated using hole-expanding ratio (X). In TBF steel, laser cutting resulted in much higher stretch-flangeability than mechanical punching. The hole-expanding ratio (X) of TBF steel austempered at 375°C in the case of laser cutting at average powers between 50 and 100 W was higher than that at 450°C, and also higher than mechanical punching. Furthermore, the strength-stretch-flangeability balance (TSX λ) of TBF steel austempered at 375°C showed the highest stretch-flangeability by laser cutting at 100 W. We found that compared with mechanical punching, YAG laser cutting contributed to the improvement of the TSXλ of 1100 MPa class TBF steel with fine bainitic ferrite matrix.

Original languageEnglish
Pages (from-to)351-356
Number of pages6
JournalTetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
Volume94
Issue number9
DOIs
Publication statusPublished - 2008 Dec 1
Externally publishedYes

Keywords

  • Retained austenite
  • Stretch-flangeability
  • Transformation-induced plasticity
  • Trip steel
  • Yag laser cutting

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Metals and Alloys
  • Materials Chemistry

Fingerprint Dive into the research topics of 'Effect of YAG laser cutting on stretch-flangeability of ultra high strength TRIP sheet steel with bainitic ferrite matrix'. Together they form a unique fingerprint.

  • Cite this