ポリゴナルフェライト母相を有するTRIP鋼板の伸びフランジ性に及ぼすYAGレーザ切断と後熱処理の影響

概要

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The effects of YAG laser cutting and post heat treatment on the stretch-flangeability of transformation-induced plasticity (TRIP)-aided sheet steels (TRIP steels), which had different content of C was examined. In TRIP steels in which Si and Mn contents were constant and C content was varied ((0.1-0.4)C-1.5Si-1.5Mn, mass%), the strength-stretch-flangeability balance (TS×λ) of holes obtained by either laser cutting, mechanical punching or drilling decreased with increasing C content. When the C content was 0.3 mass% or higher, the hole-expanding ratio (λ) value in the case of laser cutting, which originally was as good as that in the case of drilling, decreased to a level comparable to that in the case of mechanical punching. On the other hand, in TRIP steels of 0.3mass% C or higher the λ value of the hole obtained by laser cutting was low under high tensile strength (TS); however, the value was greatly improved by the post heat treatment. Based on the abore results, we demonstrated that the post heat treatment contributes to the improvement of the stretch-flangeability of (0.2-0.4)C-1.5Si-1.5Mn TRIP steels with polygonal ferrite matrix.
2006-06-30