冷轧压下率对连续退火Ti-IF钢组织和深冲性能的影响

Effect of Cold Rolling Reduction on the Microstructure and Deep Drawing Property of a Continuous Annealing Ti-IF Steel

以工业生产的Ti-IF钢热轧板为研究材料,结合连续热镀锌线的工艺特点,采用实验室冷轧、盐浴退火方法和金相、X射线织构测试和力学性能检测等分析手段,研究了冷轧压下率对组织、织构和深冲性能的影响规律。试验结果表明,随着冷轧压下率从60%提高到90%,冷轧态α取向线上的取向密度不断增强,主要形成了{223}〈110〉和{114}〈110〉织构,γ取向线上的{111}〈011〉和{111}〈112〉织构亦有所增强;退火后铁素体晶粒尺寸从9.0级细化到10.5级,导致强度(特别是屈服强度)有所增加,η_(90°)值有所降低。试验钢退火后仍具有较强的{223}〈110〉和{114}〈110〉织构,此外,随着冷轧压下率从60%提高到80%,{111}〈110〉和{111}〈112〉织构有增强的趋势,且{111}〈110〉织构比{111}〈112〉织构强,r_(90°)值有所提高;当冷轧压下率进一步提高到90%时,{111}〈112〉织构明显增强,但{111}〈110〉织构变化较小,导致{111}〈112〉织构比{111}〈110〉织构强,使r_(90°)值反而有所降低,这与γ织构分布变化导致制耳分布曲线由典型的4制耳特征转变为6制耳特征有关。

The influences of cold rolling reduction on the microstructure,textures and deep drawing property of a commercially produced Ti-IF steel after annealing were researched by means of optical microscopy,X-ray texture measurement and mechanical property testing.The results showed that when the cold rolling reduction was increased from 60%to 90%,the textures alongα-fiber skeleton were constantly enhanced and {223}〈110 and {114}〈110〉tended to be the main textures.On the other hand,{111}〈011〉and {111}〈112〉texture alongγ-fiber skeleton were also improved.At the same time,the ferrite grain size after annealing was refined from ASTM No.9.0 to No.10.5 resulting in an increase of the strength（especially the yield strength） and a decrease of n_（90°） value.The tested steel still exhibited stronger {223}〈110〉and {114}〈110〉textures after annealing.When the cold rolling reduction was increased from 60%to 80%,the {111}〈011〉and {111}〈112〉textures were constantly enhanced and the former was stronger than the latter.Therefore,the r_（90°） value was increased.When the cold rolling reduction was further increased to 90%,the {111}〈112〉texture was further enhanced but the{111}〈011〉texture remained almost unchanged.As a result,{111}〈112 texture became to be stronger than the {111}〈011〉texture,resulting in the decrease of r_（90°） value.The results could be explained by the change form 4-ear behavior to 6-ear behavior of ear-profile as a result of the shift from a curved homogeneousγ-fiber to a straightγ-fiber with a located maximum at {111}〈112〉.