| Title |
Effects of Microstructures on the Stretch Flangeability and Tensile Properties of Hot - Rolled High Strength Steel Sheets |
| Authors |
조열래(Yeol Rae Cho),정진환(Jin Hwan Chung),설경식(Kyoung Sik Seol),김인배(In Bae Kim) |
| Abstract |
The effects of the microstructures on the stretch-flangeability and tensile properties of Nb or Ti-Nb added hot-rolled high strength steel with tensile strength of 60 and 70 ㎏/㎟ grades were investigated to improve the stretch-flangeability, through the laboratory simulation and the mill-scale production. The low temperature coiling method developed using 3-step controlled cooling pattern after the finish rolling was suitable for the production of high strength steel with the polygonal ferrite and bainite phases. The enhanced stretch-flangeability of the ferrite-bainite dual phase steel was due to the fine grain boundary cementites and the decrease of deviation in hardness between the ferrite and the bainite phases, and so that void formation was suppressed relative to the other type of multi-phase steels, ferrite-bainite or ferrite-bainite-martensite steels. |