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Effect of cutting speed on surface integrity and chip morphology in high-speed machining of PM nickel-based superalloy FGH95 总被引:1,自引:1,他引:0
Du Jin Zhanqiang Liu 《The International Journal of Advanced Manufacturing Technology》2012,60(9-12):893-899
High-speed machining is being recognized as one of the key manufacturing technologies for getting higher productivity and better surface integrity. FGH95 powder metallurgy superalloy is a kind of nickel-based superalloy which is produced by near-net-shape technology. With increasing demands for high precision and high performance of FGH95 components in aerospace industry, it is essential to recognize that the machined surface integrity may determine machined part service performance and reliability. Then, little is known about the machined surface integrity of this superalloy. Thus, the surface integrity in high-speed machining of FGH95 is investigated in this paper. Experiments are conducted on a CNC milling center with coated carbide tools under dry cutting conditions. The surface integrity is evaluated in terms of surface roughness, microhardness, and white layer. The influence of cutting speed on chip morphology is also investigated. Experiment results show that surface integrity and chip morphology of FGH95 are very sensitive to the cutting speed. When cutting speeds are below 2,400?m/min, the values of surface roughness have little variation, while when cutting speeds are in the range of 2,800–3,600?m/min, the values of surface roughness are higher than that of other cutting speeds. Severe work hardening is observed resulting from high-speed machining of FGH95 superalloy. The higher the cutting speed, the higher the surface hardness. When cutting speeds are in the range of 2,800–3,600?m/min, the white layer thickness is slightly higher than that of other cutting speeds. In high-speed machining of FGH95, the chip is segmented and has a typical sawtooth shape. The degree of serrated chip increases with the cutting speed. When the cutting speeds exceed 2,400?m/min, serrated chips change into fragment chips. 相似文献
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Evaluation of surface integrity in micro drilling process for nickel-based superalloy 总被引:1,自引:1,他引:0
Muhammad Imran Paul T. Mativenga Ali Gholinia Philip J. Withers 《The International Journal of Advanced Manufacturing Technology》2011,55(5-8):465-476
This study focuses on the mechanical drilling of micro-holes in Inconel 718 alloy under wet cutting conditions. Qualitative and quantitative mechanical and metallurgical characterization of the surface and subsurface region was undertaken using nanoindentation, backscatter electron microscopy, electron backscatter diffraction microscopy and transmission electron microscopy. The analysis revealed three different zones, namely, a highly deformed nanostructured surface layer containing ultra-fine and high aspect ratio grains drawn out by large scale deformation, a deformed subsurface layer and finally the unaffected parent metal. The nano-hardness, plastic deformation, microstructure and crystal misorientation were assessed. The correlation between the modified surface and subsurface layers and the cutting conditions was established. The phenomena behind the formation of the different zones were investigated. The results suggest that subsurface alterations are driven by thermo-mechanical loading, causing plasticity and grain refinement by excessive shearing local to the cut surface. 相似文献
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Nickel-based single crystal superalloy is widely used in the field of aerospace and nuclear reaction equipment due to its good properties. Ultra-precision machining technology is an important means to ensure the surface quality of parts. However, the anisotropy of materials has great influence on the evolution of surface and subsurface defects and the removal of materials in the process of machining. In this paper, The MD (molecular dynamics) modeling and simulation verification of cutting anisotropic nickel-based single crystal superalloy workpiece with silicon nitride tool is carried out by using the mixed potential function simulation. Through cutting simulation and visualization, the types, number, deformation area and dislocation evolution of the machined surface defects and inside of the workpiece defect of nickel-based single crystal superalloy with different crystal orientations are analyzed. The evolutionary mechanism of the machined surface defects and the law of material removal are discussed. The research content provides a theoretical basis for parameter optimization and improvement of machining quality in the atomic and close-to-atomic scale (ACS) cutting process, and technical support for efficient and precise machining process of the nickel-based superalloy. 相似文献
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Study of cutting speed on surface roughness and chip formation when machining nickel-based alloy 总被引:1,自引:0,他引:1
Nickel-based alloy is difficult-to-machine because of its low thermal diffusive property and high strength at higher temperature.
The machinability of nickel- based Hastelloy C-276 in turning operations has been carried out using different types of inserts
under dry conditions on a computer numerical control (CNC) turning machine at different stages of cutting speed. The effects
of cutting speed on surface roughness have been investigated. This study explores the types of wear caused by the effect of
cutting speed on coated and uncoated carbide inserts. In addition, the effect of burr formation is investigated. The chip
burr is found to have different shapes at lower speeds. Triangles and squares have been noticed for both coated and uncoated
tips as well. The conclusion from this study is that the transition from thick continuous chip to wider discontinuous chip
is caused by different types of inserts. The chip burr has a significant effect on tool damage starting in the line of depth-of-cut.
For the coated insert tips, the burr disappears when the speed increases to above 150 m/min with the improvement of surface
roughness; increasing the speed above the same limit for uncoated insert tips increases the chip burr size. The results of
this study showed that the surface finish of nickel-based alloy is highly affected by the insert type with respect to cutting
speed changes and its effect on chip burr formation and tool failure. 相似文献
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The shape of the tool insert geometry, particularly the size of the tool nose radius, plays a significant role in influencing a variety of surface integrity characteristics such as surface finish, roundness, tool life, edge frittering etc. It has been found in previous work that a large tool nose radius is beneficial in improving the component quality. This paper substantiates these facts and shows that increasing the feed rate generally debilitates the surface integrity but, probably due to some elasticity in the porous compact's surface, this does not cause residual hardening to the machined surface. Abrasion during secondary machining suggests that flank, rather than crater, wear determines the end point during cutting operations. Tool nose geometry plays a significant role in improving surface topography, by reducing the cusp height—when the nose radius is large. The manufacturing envelopes defined by skewness and kurtosis for the machined surfaces suggest that there is a general drift either from a bearing to a locking surface or vice versa. Furthermore, the dispersion of these envelopes reduces with increasing feed rate. These conditions can be attributed to the tool nose geometry, feed rate and depth of cut which modifies the machined surface topography. 相似文献
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Carl-Frederik Wyen Dominik Jaeger Konrad Wegener 《The International Journal of Advanced Manufacturing Technology》2013,67(1-4):589-599
The influence of the cutting edge micro geometry on cutting process and on tool performance is subject to several research projects. Recently, published papers mainly focus on the cutting edge rounding and its influence on tool life and cutting forces. For applications even more important, however, is the influence of the cutting edge radius on the integrity of the machined part. Especially for titanium, which is used in environments requiring high mechanical integrity, the information about the dependency of surface integrity on cutting edge geometry is important. This paper therefore studies the influence of the cutting edge radius on surface integrity in terms of residual stress, micro hardness, surface roughness and optical characterisation of the surface and near surface area in up and down milling of the titanium alloy Ti–6Al–4V. Moreover, the influence of the cutting edge radius on burr formation is analysed. The experiments show that residual stresses increase with the cutting edge radius especially in up milling, whereas the influence in down milling is less pronounced. The influence of the cutting edge radius on surface roughness is non-uniform. The formation of burr increases with increasing cutting edge radius, and is thus in agreement with the residual stress tests. 相似文献
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Qi Gao Yadong Gong Yunguang Zhou Xuelong Wen 《Journal of Mechanical Science and Technology》2017,31(1):171-180
Micro-milling is widely used as a method for machining of micro-parts with high precision and efficiency. Taking the nickel-based single-crystal superalloy DD98 as the research object, the crystal characteristics of single-crystal materials were analysed, and the removal mechanism of single-crystal micro-milled parts was described. Based on molecular dynamics, a simulation model for nickel-based single-crystal superalloy DD98 micro-milling was established. Based on the response surface method of central composite design, the influences of spindle speed, feed rate, and milling depth on the surface roughness were examined, and a second-order regression model of the DD98 surface roughness was established. Using analysis of variance and the residuals of the model, a significant influence on surface roughness was found in the following order from large to small: Feed rate, spindle speed, and milling depth. Comparisons were conducted between the micro-milling experimental values and the predicted model values for different process parameters. The results show that the model fit is relatively high, and the adaptability is good. Scanning electron microscopy analysis of the micro-milling surfaces was performed to verify the slip and the removal mechanism of single-crystal materials. These results offer a theoretical reference and experimental basis for micro-milling of single-crystal materials. 相似文献
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A. S. Dudarev 《Russian Engineering Research》2014,34(10):660-662
The life of cutting tools is considered in situations with variation in the cutting speed. 相似文献
10.
目前有关刀具钝化对切削力和加工零件表面粗糙度的影响的研究比较少.通过单因素法对比试验,分别测出在不同切削参数下刀具钝化引起的切削力及加工后零件表面粗糙度的变化.分析结果表明,随着切削速度的增加,刀具钝化后的切削力增加了,Fx和Fz方向增加比较明显;随着径向、轴向切深的增加,钝化刀具切削时的切削力增加了,F2增加的最明显.随着切削速度、径向切深及轴向切深的增加,表面粗糙度都明显减小,加工工件的表面质量得以改善. 相似文献
11.
Research on sub-surface recrystallization of single crystal nickel-based superalloy in micro-milling
Journal of Mechanical Science and Technology - The micro-structure/parts of single crystal nickel-based superalloy materials are extensively used in high temperature environments. The... 相似文献
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Tribological behaviour of an electrodischarge machined surface with a powder metallurgy bronze electrode 总被引:1,自引:0,他引:1
Metal transfer from the tool electrode to the machined surface is appreciable in electrodischarge machining when a powder compact tool electrode is used under reverse polarity conditions. A powder metallurgy bronze electrode was employed in the present work and investigation of the frictional behaviour of the resultant surface showed considerable reduction in the friction coefficient. Reduction in wear was also confirmed by a new method using cutting tests, establishing that the surfaces can be used in applications involving extreme pressure and velocity. 相似文献
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采用热-机耦合方法,利用Marc软件,在经过准确性验证的粉末冶金闸瓦踏面制动计算模型上,专门针对粉末冶金闸瓦的主要制动参数摩擦体脱落面积和不同初始制动速度下闸瓦摩擦系数变化偏差范围(±0.04或±0.03)对制动试验结果的影响进行了验证性的仿真计算研究.仿真计算结果表明,闸瓦摩擦体脱落10%,车轮踏面最高温度增加52℃,制动距离未发生明显变化;不同初始制动速度下闸瓦摩擦系数变化偏差范围对车轮踏面的最高温度和制动距离影响较小,偏差范围设置合理. 相似文献