Abstract: On the basis of the successful developed ferrite zone rolling process technology in a hot rolling plant production line， a comparative study was conducted to investigate the effects of two hot rolling processes， on the metallographic microstructure， precipitation phases， macroscopic texture and mechanical properties of low-strength IF steel. OM， TEM and XRD diffraction were used to compare and analyse the differences in metallographic microstructure， precipitation phases and macroscopic texture of IF steel in hot-rolled and cold-rolled annealed condition under the two rolling processes， and at the same time， the three-way tensile mechanical properties of IF steel were tested by the ZWICK tensile tester after cold-rolled annealing. The results show that the microstructure of hot-rolled IF steels in the austenitic zone was equiaxed grains， while the grains of hot-rolled IF steel in the ferrite zone are elongated and fibrous along the rolling direction； Compared with the austenitic zone hot rolling process， the optimum process parameters for ferrite zone rolling are heating temperature 1 150 ℃+final rolling temperature 800 ℃+coiling temperature 720 ℃， in which the yield strength Rp0.2 is significantly reduced， and the size of precipitated phases is overall larger by 70-85 nm， but there is no significant difference in the size of TiN precipitated phases； In terms of texture， cold-rolled annealed IF steel γ texture is stronger， and the orientation distribution of each component in the main texture is more concentrated with smaller differences in strength.The corresponding r value increases by 0.64， while the △r value decreases by 0.35， significantly improving its deep drawing formability. This provides a technical reference for promoting the application of ferrite rolling technology.

Key words: Low-strength IF Steel, Ferrite Rolling, Microstructure Property, Precipitate, Texture

摘要： 在某热轧厂产线成功开发出铁素体区轧制工艺技术的基础上，对比研究了铁素体区轧制和奥氏体区轧制两种热轧工艺对低强度IF钢组织、析出相、宏观织构及力学性能的影响。采用OM、TEM和XRD衍射仪等检测方法，对两种工艺下热轧、冷轧退火IF钢金相组织、析出相以及宏观织构的差异进行了对比研究，同时采用拉伸试验机检测了冷轧退火后IF钢三向拉伸力学性能。研究表明：奥氏体区热轧金相显微组织为等轴状铁素体晶粒，铁素体区热轧组织晶粒沿轧向被拉长呈纤维状；相比奥氏体区热轧工艺，铁素体区轧制最佳工艺参数为加热温度1 150 ℃+终轧温度800 ℃+卷取温度720 ℃，在此工艺下显著降低了屈服强度R_p0.2，析出相尺寸整体大70~85 nm，但TiN析出相尺寸无明显差异；织构方面，冷轧退火IF钢γ织构更强，主要织构各组元取向分布更集中且强度差异较小，r相应值提高0.64，△r值降低0.35，大大提高了其深冲成形性能，为推广铁素体轧制工艺的应用提供了技术参考。

关键词: 低强度IF钢, 铁素体轧制, 组织性能, 析出物, 织构