基于X射线衍射线形分析的铝合金切削表层晶体特征研究

摘要

In order to obtain a better understanding of the mechanism of cutting surface microstructure in the high-speed cutting processes and meet the strict requirements of various components on the service performance,based on micro view,the 7050-T7451 aluminum alloy was studied.For solving the problems that traditional observation method was difficult to obtain the statistical rule of grain sizes and dislocation densities,based on X-ray diffraction profile analyses such as Modified Warren-Averbach and Modified Williamson-Hall the methods were introduced into analyzing the microstructure of cutting surfaces from materials science and physics.Quantitative studies on microstructure of cutting surfaces under different cutting speeds were achieved.The results show that the machined surface is dominated by edge dislocations under high speed cutting conditions.The dislocation density values and rules are obtained.The formation mechanism is explained from plastic deformation and energy.The grain size distribution curve is fitted.The uniformities of the grains on the cutting surface are analyzed by the distribution function.When the cutting speed is higher than 4500 m/min,the cutted surfaces with relatively low dislocation density and uniform grain size may be obtained.%为深入研究高速高效加工条件下材料表层晶体特征形成机理,提高铝合金构件服役性能,同时解决传统观察法较难得出晶粒尺寸与位错密度统计学规律的问题,立足微观,以铝合金7050-T7451为研究对象,将材料学与物理学中基于X射线衍射线形分析的Modified Warren-Averbach和Modified Williamson-Hall方法引入切削加工表层微观组织分析中,实现了不同切削速度下切削表层微观组织结构的定量研究.研究表明,高速切削条件下已加工表面以刃位错为主,得出了位错密度值(高达1015 m-2以上)与位错密度变化规律,并从塑性变形及能量角度解释了其形成机理;拟合出了晶粒尺寸分布曲线,并通过分布函数分析了已加工表面晶粒分布均匀性;当切削速度高于4500 m/min时可以得到位错密度相对较低、晶体尺寸较均匀的已加工表面.