TRIP型ベイニティックフェライト鋼板の伸びフランジ性に及ぼすYAGレーザ切断パルスエネルギーの影響

概要

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In the present work, effect of YAG laser cutting pulse energy on stretch-flangeability in 0.2C-1.5Si-1.5Mn ultra high-strength TRIP-aided sheet steel with bainitic ferrite matrix (TBF steel) which were austempered at 375 or 450℃ was investigated for automotive applications. The tensile strength (TS) of TBF steel austempered at 375℃ was higher than that of TBF steel austempered at 450℃. The press formability of laser cut surface layer was investigated by hole-expanding test. On the other hand, the stretch-flangeability (λ) of TBF steel in the case of hole-punching austempered at 375℃ was larger than that of TBF steel austempered at 450℃. Further, the stretch-flangeability austempered at 375℃ in the case of laser cutting at 4J/P was larger that that of 450℃. The strength-stretch-flangeability balance (TS×λ) of TBF steel austempered at 375℃ became maximum by laser cutting at 4J/P. The good stretch-flangeability was completed by laser cutting at 4J/P in TBF steel austempered at 375℃. The stretch-flangeability of laser cut hole depended on surface roughness in TBF steel austempered at 375℃. When a suitable condition of laser cutting is selected, the stretch-flangeability of laser cut hole is better than that of punched hole.
長野工業高等専門学校の論文