7．9Mn－1．4Si－0．07C钢高强韧机理研究

通过热轧、温轧、奥氏体化、两相区退火处理得到7．9Mn－1．4Si－0．07C钢板，该材料的拉伸强度及塑性随奥氏体化温度不同而具有显著差异．奥氏体化温度降低，室温下奥氏体含量升高，综合力学性能提高．当奥氏体化温度由900℃降低为800℃时，所得到钢板的奥氏体体积分数由15％增加到28％，拉伸强度由1150MPa提高到1340MPa，塑性由21％提高至27％．实验钢优异的力学性能源于其中大量的超细铁素体及奥氏体，细晶强化使其具有超高强度，铁素体基体及变形过程中奥氏体向马氏体相变提供了良好的塑性．基体组织中的位错强化，形变诱导马氏体转变的TRIP效应等是增强该钢板加工硬化能力的主要因素．

Investigation on mechanism of improved toughness for 7. 9Mn -1.4Si -0. 07C steel

A 7.9Mn - 1.4Si - 0. 07C steel plate was obtained by hot - rolling, warm - rolling, austenization and intercritical annealing. The plate exhibited different mechanical properties with variations of the austenization temperature. The austenite volume fraction and mechanical properties increased with decreasing austenization temperature. When annealing temperature was changed from 900 ℃ to 800℃, the austenite volume fraction, tensile strength and ductility of the sample increased from 15% to 28% , 1 150 MPa to 1 340 MPa, and 21% to 27% , respectively. The excellent mechanical properties were mainly due to presence of a large volume fraction of ultrafine ferrite and austenite lamellae. The ultrafine ferrite and the phase transformation from austenite to martensite in deformation provided good ductility. Dislocation in the matrix and deformation -induced transformation from martensite to TRIP and etc. were the main factors making the steel plate intensified.