【摘要】 以TMCP(Thermo Mechanical Control Process)实验获得的低成本热轧FB(Ferrite/Bainite)钢为研究对象,通过扩孔实验评价FB钢板的延伸凸缘性能,分析显微组织对延伸凸缘性能的影响,并对扩孔过程中FB钢的裂纹扩展行为进行探讨。结果表明:当贝氏体体积分数在19~25%时,热轧FB钢的抗拉强度不低于551 MPa、扩孔率不小于77%,力学性能和延伸凸缘性能综合起来比较良好;裂纹通过孔洞和微裂纹相互扩展、连接的方式进行;当裂纹扩展到硬相的贝氏体时,裂纹沿着铁素体和贝氏体的相界面绕过贝氏体,并切断铁素体继续扩展。更多还原

【Abstract】 Hot-rolled FB( Ferrite / Bainite) steels with low cost prepared by TMCP( Thermo Mechanical Control Process) experiment were used to as study subjects. The stretch-flange ability of the FB( Ferrite / Bainite) steels was evaluated through hole-expansion tests. The effects of microstructure on the stretch-flange ability were discussed in detail. Crack formation and propagation behavior during the holeexpansion process were also investigated. The results show that hot rolled FB steels show good mechanical properties and stretch-flange ability when the volume fraction of bainite between 19% and 25%,tensile strength and hole expanding rate are not less than 551 MPa and77%,respectively. The crack in FB steels is formed by the micro void coalescence. When micro-crack meet bainite,it mostly propagates along phase interfaces between ferrite and bainite by cutting off ferrite grains.更多还原