ベイニティック・フェライト組織高強度熱延鋼板の伸びフランジ性
2001 年 87 巻 3 号 p. 146-151
詳細
2001 年 87 巻 3 号 p. 146-151
Recently, high strength hot rolled steel sheets have been applied to mainly chassises and wheels and high formability, especially high stretch-flangeability is required on those parts. Bainitic-ferrite single phase microstructure has been proposed to obtain the high stretch-flange formability. In this paper, the effects of metallurgical factors of bainitic-ferrite single phase microstructure on stretch-flangeability is studied.
The effects of atomic ratio of Ti by C of the bainitic ferrite steel and the void creation morphology of bainitic-ferrite, bainite and ferrite-pearlite steel after stretch flange formation are investigated. The bainitic-ferrite steels with access of 1.0 atomic ratio of Ti by C shows highest stretch-flangeability among the studied steels because cementite is not existed.
Cemmentite existed in baintic-ferrite steels with 0.5 atomic ratio of Ti by C, bainite and ferrite-pearlite steels, causes the void initiation during stretch flange formation. In addition of above mentioned, the stretch-flangeability is deteriorated by TiC precipitate and increase grain size.
