运用ABAQUS有限元软件建立了γ-TiAl 金属间化合物铣削加工的细观模型,分析了不同材料模型的加工表面形貌及边缘断裂形成机理。结果表明,由于片层之间的材料特性不同,加工过程中片层与片层之间更容易出现裂纹或凹坑。同时,由于其较低的延展性,γ-TiAl 金属间化合物加工出口处形成较大的负剪切平面,从而导致边缘断裂。通过与实验结果比较,发现γ-TiAl 金属间化合物铣削加工表面粗糙度和边缘断口尺寸均小于由正六边形片层细观模型所得的模拟值,且略高于由矩形片层细观模型所得的模拟值。同时,加工表面粗糙度和边缘断口尺寸随切削深度的增加而逐渐增大,而切削速率的影响较小。因此,为了得到更好的加工表面质量,γ-TiAl 金属间化合物加工过程中应尽可能地采用较高的切削速率,而不是切削深度。
γ-TiAl intermetallics are attractive candidates for applications in aircraft turbine engines due to their low density and good mechanical properties at high temperature. However, the low room temperature ductility makes the machinability of these materials poorer compared to the conventional alloys. In this work, a meso-model of γ-TiAl intermetallic was developed using ABAQUS finite element software. The surface morphology and edge fracture mechanism of different material models were analyzed, and the effects of cutting parameters on the surface roughness and size of edge fracture were investigated. The results indicate that the cracks and pits occur between the lamellar and lamellar with different material properties. At the same time, due to the low ductility of γ-TiAl intermetallic, the negative shear angle begins to form at the exit of workpiece, then the edge fracture is formed. In addition, for both surface roughness and size of edge fracture, the experimental data are slightly higher than the simulated data obtained by the hexagonal lamellar model, and smaller than those obtained by the rectangular lamellar model. With the increasing of cutting depth, the surface roughness and the size of edge fracture increase gradually, on the contrary, the cutting speed has a small effect on them. Therefore, in order to obtain a fine surface quality during machining of γ-TiAl intermetallic, the cutting speed can be adopted as higher as possible, but not the cutting depth.
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