Understanding the relationship between microstructure features and mechanical properties is of great significance for the improvement and specific adjustment of steel properties. The relationship between mean grain size and yield strength is established by the well-known Hall-Petch equation. But due to the complexity of the grain configuration within materials, considering only the mean value is unlikely to give a complete representation of the mechanical behavior. The classical Taylor equation is often used to account for the effect of dislocation density, but not thoroughly tested in combination with grain size influence. In the present study, systematic heat treatment routes and cold rolling followed by annealing are designed for interstitial free (IF) steel to achieve ferritic microstructures that not only vary in mean grain size, but also in grain size distribution and in dislocation density, a combination that is rarely studied in the literature. Optical microscopy is applied to determine the grain size distribution. The dislocation density is determined through XRD measurements. The hardness is analyzed on its relation with the mean grain size, as well as with the grain size distribution and the dislocation density. With the help of the variable selection tool LASSO, it is shown that dislocation density, mean grain size and kurtosis of grain size distribution are the three features which most strongly affect hardness of IF steel.

了解微观组织特征与力学性能之间的关系对于改善和具体调节钢性能具有重要意义。平均晶粒尺寸与屈服强度之间的关系通过众所周知的Hall-Petch方程建立。但是由于材料中晶粒结构的复杂性，仅考虑平均值不可能完全代表机械性能。经典的泰勒方程通常用于解释位错密度的影响，但没有结合晶粒尺寸的影响进行彻底测试。在本研究中，为无间隙（IF）钢设计了系统化的热处理路线和冷轧后进行退火的工艺，以实现不仅平均晶粒尺寸有所变化的铁素体显微组织，而且还有晶粒尺寸分布和位错密度，这是文献中很少研究的组合。应用光学显微镜确定晶粒尺寸分布。位错密度是通过XRD测量确定的。分析硬度与平均晶粒尺寸，晶粒尺寸分布和位错密度的关系。借助于变量选择工具LASSO，表明位错密度，平均晶粒度和晶粒度分布的峰度是影响IF钢硬度的三个特征。分析硬度与平均晶粒尺寸，晶粒尺寸分布和位错密度的关系。借助于变量选择工具LASSO，表明位错密度，平均晶粒度和晶粒度分布的峰度是影响IF钢硬度的三个特征。分析硬度与平均晶粒尺寸，晶粒尺寸分布和位错密度的关系。借助于变量选择工具LASSO，表明位错密度，平均晶粒度和晶粒度分布的峰度是影响IF钢硬度的三个特征。