Abstract:  Based on the real machining parameters， this paper investigated the effects of milling speed， feed per tooth， stepover， milling depth and coolant on the surface integrity of the integral impellers， which includes the aspects such as surface roughness， surface morphology， surface microhardness， microstructure and residual stress. The results show that stepover and feed per tooth have the most significant influence on the surface roughness， the smaller stepover and feed per tooth value result in smaller blade surface roughness. Specifically， when the stepover is decreased from 0.3 mm to 0.16 mm， the average roughness value reduces from 0.64 μm to 0.48 μm； as the feed per tooth is decreased from 0.1 mm to 0.06 mm， the average roughness value decreases from 0.62 μm to 0.4 μm. Both of the stepover and feed per tooth significantly impacts the surface morphology. As the stepover and feed per tooth increase， the row spacing residual height and feed residual height also increase. Since the selected machining parameters are relatively reasonable， blade surface is observed to be smooth without the production of defects such as scratches， scrapes， and burrs， etc. Moreover， under the reasonable machining parameters， the generated force and heat are insufficient to alter the surface microhardness， which fluctuates around 335HV for each machining parameters， leading to no distinct difference in the surface hardening layer compared to the substrate. The residual stresses observed are predominantly compressive stresses， with limited correlation to the stepover and milling depth. When considering the milling speed and feed per tooth， the surface compressive stress initially increases and 
then decreases. Along the depth direction， compressive stress initially slightly decreases， reaches a peak， and finally stabilizes within the matrix. The maximum residual stress reaches to 275 MPa and 400 MPa in the parallel and perpendicular feed directions， respectively. Surface residual stress under the water-based coolant is much higher than that under the oil-based coolant， but decreases significantly in the depth direction. 

Key words: integral impeller, machining parameter, surface integrity, milling

摘要： 考虑叶轮真实加工参数，探究了切削速度、每齿进给量、行距、切深、冷却液对整体叶轮叶片的表面完整性（包括表面粗糙度、表面形貌、表面显微硬度、金相组织、残余应力）的影响。结果表明：行距和每齿进给量对叶片表面粗糙度影响最大，行距和每齿进给量越小，叶片表面粗糙度越小，当行距从0.3 mm减小至0.16 mm时，平均粗糙度Ra从0.64 μm减小至0.48 μm，当每齿进给量从0.1 mm减小至0.06 mm时，平均粗糙度从0.62 μm 减小至0.4 μm；行距和每齿进给量对表面形貌影响最为明显，随着行距和每齿进给量的增大，叶片表面的残留高度增大；切削参数选取相对合理，叶片表面没有产生划痕、划伤和毛刺等缺陷；在合理的参数条件下，叶片表面的力热水平较低，使得叶片表面的显微硬度变化不明显，各切削参数下表面平均硬度在335HV左右浮动，同时也没有产生区别于基体的变质层；叶片表层残余应力均表现为压应力，行距、切深对残余应力的影响较小；随切削速度和每齿进给的增大，表层压应力先增大后减小，沿深度方向表现出先微弱减小再增大到峰值最后到达基体的趋势，平行和垂直进给方向上最大残余应力分别可达275 MPa和400 MPa；水基冷却液在加工表层达到远大于油基冷却液的残余压应力，但残余应力在深度方向下降明显。

关键词: 整体叶轮, 工艺参数, 表面完整性, 铣削