Performance and wear mechanism of spark plasma sintered WC-Based ultrafine cemented carbides tools in dry turning of Ti–6Al–4V

Cutting performance and failure mechanisms of spark plasma sintered (SPS) ultrafine cemented carbides in dry turning Ti–6Al–4V were studied. The tools of UYG8 (WC-8wt%Co) and UYG8V2B10 (WC-8wt%Co-0.2 wt%VC-1.0 wt%cBN) exhibited higher lifetime and better processing quality than the commercial YG8 cemented carbide tool. The cutting distance of UYG-8 and UYG8V2B10 tools are 1.8 and 1.6 times longer than that of YG8, respectively. Cutting-edge breakage was found as the main failure forms of the SPS cemented carbide tools containing low Co content (≤6 wt%), whereas the SPS cemented carbide tools containing high Co content (≥8 wt%) exhibited flank and rake wear as main failure forms caused by abrasion, adhesion, diffusion, and oxidation. UYG8V2B10 tool wear mechanism was affected by cutting speed and depth. Wear mechanisms of UYG8V2B10 tool are mainly adhesive wear and oxidative wear at low cutting speed, but follow adhesive wear and diffusive wear at higher cutting speed. Moreover, with increasing cutting depth, tool failure forms are mainly breakage and chipping, largely induced by high cutting temperature and severe cutting vibration.     

Cutting performance,failure mechanisms and tribological properties of GNPs reinforced Al2O3/Ti(C,N) ceramic tool in high speed turning of Inconel 718

Cutting performance and failure mechanisms of graphene nano-platelets (GNPs) reinforced ceramic cutting tool ATG (short for Al₂O₃/Ti(C,N)/GNPs) in continuous dry turning of Inconel 718 up to a cutting speed of 500 m/min were investigated in comparison with those of commercial Sialon tool KY1540. The results show that ATG tool shows similar cutting performance with KY1540 tool at the speed range of 150–300 m/min, but greatly outperforms KY1540 when the cutting speed range of 400–500 m/min for higher hardness, wear resistance, chemical inertness and fracture toughness. Flank wear, notch wear, chipping and flaking are the reasons for tool failure of ATG. The wear modes are related to cutting speed, and adhesion wear is found to be the dominant failure mechanism of ATG. It is believed that GNPs play a significant role in improving mechanical properties and tribological properties which contributed to excellent resistance to abrasive wear and fracture. Turning Inconel 718 in dry and high speed via using ATG ceramic tool is an efficient and eco-friendly method.     

Self-lubricating behaviors of Al2O3/TiB2 ceramic tools in dry high-speed machining of hardened steel

In this paper, Al₂O₃/TiB₂ ceramic cutting tools with different TiB₂ content were produced by hot pressing. The fundamental properties of these ceramic cutting tools were examined. Dry high-speed machining tests were carried out on hardened steel. The tool wear, the cutting temperature, the cutting forces, and the friction coefficient between the tool and the chip were measured. It was shown that both the wear rates and the friction coefficient at the tool–chip interface of Al₂O₃/TiB₂ ceramic cutting tools in dry high-speed machining of hardened steel were reduced compared with that of in low-speed machining. The mechanisms responsible were determined to be the formation of a self-lubricating oxide film on the tool–chip interface owing to the tribological–chemical reaction by the elevated cutting temperature. The composition of the self-lubricating film was found to be the oxidation product of TiB₂ grains, which serves as lubricating additive on the wear track of the tool rake face. The appearance of this self-lubricating oxide film contributed to the improvement in wear resistance and the decrease of the friction coefficient. This action was even more effective with higher TiB₂ content. Cutting speed was found to have a profound effect on the self-lubricating behavior. In dry low-speed machining of hardened steel, the Al₂O₃/TiB₂ tools showed mainly adhesive and abrasive wear. While in dry high-speed machining, oxidation wear of the ceramic tools was the dominant mechanism due to the very high cutting temperature. No oxide film was formed on the tool–chip interface while machining in nitrogen atmosphere, and the tool wear resistance was correspondingly decreased.     

High-entropy carbide-based ceramic cutting tools

In this study, a novel high-entropy carbide-based ceramic cutting tool was developed. The cutting performance of three kinds of high-entropy carbide-based ceramic tools with different mechanical properties for the ISO C45E4 steel were evaluated. Although the pure (Ti_0.2Zr_0.2Nb_0.2Ta_0.2Mo_0.2)C_0.8 ceramic cutting tool exhibited the highest hardness of 25.06 ± 0.32 GPa, the cutting performance was poor due to the chipping and catastrophic failure caused by the low toughness (2.25 ± 0.27 MPa m^1/2). The (Ti_0.2Zr_0.2Nb_0.2Ta_0.2Mo_0.2)C_0.8–15 vol% cobalt cutting tool with highest fracture toughness (6.37 ± 0.24 MPa m^1/2) and lowest hardness (17.29 ± 0.79 GPa) showed the medium cutting performance due to the low wear resistance caused by the low hardness. The (Ti_0.2Zr_0.2Nb_0.2Ta_0.2Mo_0.2)C_0.8–7.7 vol% cobalt cutting tool showed the longest effective cutting life of ∼67 min due to the high wear resistance and chipping resistance caused by the high hardness (21.05 ± 0.72 GPa), high toughness (5.35 ± 0.51 MPa m^1/2), and fine grain size (0.60 ± 0.15 μm). The wear mechanisms of the cobalt-containing (Ti_0.2Zr_0.2Nb_0.2Ta_0.2Mo_0.2)C_0.8 ceramic cutting tools included adhesive wear and abrasive wear and oxidative wear. This research indicated that the high-entropy carbide-based ceramics with high hardness and high toughness have potential use in the field of cutting tool application.     

Effect of impact angle on wear behavior of Mo2NiB2–Ni cermets with different Ni content

Herein, the influence of the impact angle and Ni content on the wear behavior of Mo₂NiB₂–Ni cermets was studied using an erodent-carrying slurry comprising artificial seawater and SiO₂ sands. The results reveal that the material loss may be attributed to the wear damage caused by SiO₂ sands because cermets are expected to exhibit good corrosion resistance in artificial seawater. The relative density of cermets markedly influences their resistance to wear damage, and the material loss experienced by cermets with poor relative density is 2–4 times higher than that of cermets with good relative density; this occurs because a higher relative density can markedly enhance the mechanical properties and reduce the defects in the cermets. Moreover, the results indicate that as the impact angle increases from 0° to 60°, the manifestation of the wear mechanism changes from damaging the Ni binder phase (caused by single cutting wear) to damaging both the Mo₂NiB₂ ceramic and Ni binder phases due to the combination of cutting wear and impact wear. The wear damage is dominated by the cutting wear and impact wear from SiO₂ sand at the low and high impact angles, respectively. Furthermore, the severe deterioration of the single ceramic skeleton at high impact angles indicates that the synergistic influence of the Mo₂NiB₂ ceramic and Ni binder phases on enhancing the wear resistance of the cermets intensifies at high impact angles.     

Applicability of DLC and WC/C low friction coatings on Al2O3/TiCN mixed ceramic cutting tools for dry machining of hardened 52100 steel

The present work examines the applicability of DLC and WC/C low friction coatings on Al₂O₃/TiCN based mixed ceramic cutting tools for the dry and hard turning of AISI 52100 steel (62 HRC). The characterization of coated tools reveals that the coatings retain very low values of surface roughness, whereas the DLC coating exhibits much higher microhardness when compared to the WC/C coating. On the other hand, the WC/C coating exhibit a coarse surface morphology virtually due to the tungsten doping. Later, continuous turning tests were executed with the help of coated and uncoated cutting tools under dry cutting conditions, and their performance was investigated in terms of machining forces, cutting temperature and tool wear. Coating delamination by flaking and peeling is quite prominent in the case of both the coatings; however, it is less severe for the WC/C coated tool. The coatings help to reduce machining forces, cutting temperatures and tool wear, but the performance of coated tools converge towards uncoated tool as the cutting speed, and feed rate is increased. Both the coatings prevent the development of cracks near the cutting edge with WC/C coating exhibiting superior wear behavior basically due to its multilayered structure and better thermal stability. Moreover, the tested low friction coatings don't serve as thermal barriers and only the lubrication generated due to graphitization at the chip-tool interface is mostly responsible for the improved machining performance.     

Finite element simulation and experimental analysis of B4C-TiB2-SiC ceramic cutting tools

Here, cutting properties and wear mechanism of the home-made B₄C-TiB₂-SiC ceramic cutting tools in turning of AISI 4340 steel workpieces were studied through a combination of finite element simulation using Deform-3D software and turning experiments. Simulation results show that cutting parameters have significant effects on the main cutting force and tool temperature of the B₄C-TiB₂-SiC cutting tool. The optimal cutting parameters for the ceramic cutting tool are cutting speed of 300 m/min, depth of cut of .3 mm, and feed rate of .1 mm/r. Experimental results show the cutting length of the B₄C-TiB₂-SiC cutting tool is about 101 m, which is 21.0% and 32.9% larger than that of the home-made B₄C-TiB₂ ceramic cutting tool and commercially available tungsten carbide tool, indicating that the B₄C-TiB₂-SiC cutting tool has a desired service life. The surface roughness of the workpieces processed by the B₄C-TiB₂-SiC cutting tool is 2.43 µm, which is 29.4% lower than that of the workpieces processed by the B₄C-TiB₂ cutting tool, indicating that the B₄C-TiB₂-SiC cutting tool has a satisfying machining accuracy. Wear forms of the B₄C-TiB₂-SiC ceramic cutting tool involve craters, chipping, and flank wear, and the main wear mechanisms are abrasive, adhesive, oxidative, and diffusion wear.     

Analysis of cutting responses of Sialon ceramic tools in high-speed milling of FGH96 superalloys

Powder metallurgy superalloy FGH96 is being extensively used to fabricate the hot section of the aeronautic and astronautic turbine engines owing to its superior mechanical properties maintained at high-temperature environments. However, machining such a difficult-to-cut material entails high cutting forces, excessive cutting temperatures and serious tool wear. Although Sialon ceramic tools have been successfully employed in the turning and milling processes for the Inconel 718, their application for the machining of powder metallurgy superalloys is very limited. In the current work, a series of high-speed milling trials were conducted to examine the influences of the milling parameters on the cutting response and tool wear mechanisms during the milling of FGH96 with Sialon ceramic mills under dry conditions. The milling forces and machining temperatures were studied with respect to the used process parameters. The quality of cut surfaces and wear signatures of ceramic tools were also discussed. Results indicate that the resultant cutting forces only decrease until the cutting speed exceeds 315 m/min. Furthermore, the Sialon tools seem more suitable for the rough machining of FGH96 considering the surface finish and large residual tensile stress existing on the milled surface. Finally, the adhesion wear is the primary wear mode occurring at the flank surface, while the edge chipping and flaking dominate the failure of the tool rake surface.     

Performance of Si3N4/(W,Ti)C graded ceramic tool in high-speed turning iron-based superalloys

A Si₃N₄/(W, Ti)C graded nano-composite ceramic tool was fabricated and its performance in high speed turning iron-based alloys GH2132 was investigated compared with homogeneous and commercial ceramic tools. The chip morphology, cutting forces, cutting temperature, tool life and failure mechanisms and machined surface roughness were recorded and analyzed. The results showed that with the increasing cutting speed the resultant cutting force shows a tendency to first increase and then decrease while the cutting temperature increases gradually. Straight continuous chips, bending continuous chips, twist continuous chips and snarled chips form in turn. Saw-tooth chips tend to form when the cutting speed is more than 200?m/min. The graded tool shows longer tool life especially at the cutting speed of 150 and 200?m/min compared with the homogenous and commercial ceramic tools. Tool failure modes mainly include grooving on the rake face, notching on the flank face, abrasion and adhesion. The grooving on the rake face tends to decrease while notching on the flank face tends to increase as cutting speed increases. Surface roughness of the machined iron-based super-alloys is relatively high due to the serious adhesion. Better surface roughness can be got using the graded tool.     

Cutting performance and wear mechanism of TiB2-B4C ceramic cutting tools in high speed turning of Ti6Al4V alloy

TiB₂–20vol%B₄C (TB20) and TiB₂–80vol%B₄C (TB80) ceramic cutting tool materials were prepared by hot pressing, and then tested in turning of Ti6Al4V alloy with various cutting parameters. The tool life and wear mechanism of TB20 and TB80 were studied and compared with a commercial grade tungsten carbide tool (WO). The results of turning showed that effective cutting length of TB20 was about one third longer than that of TB80 and WO. Among the three tools, the increment of cutting temperature measured for TB20 was the lowest as flank wear increased from 0 to 600?µm. Analysis showed that dominant wear mechanism was adhesive wear in all of the three tools tested, while chipping was also observed in TB80 and temperature deterioration in WO. In addition, the TB20 exhibited a much better integrity of cutting edge after flank wear reaching 600?µm, due to its higher toughness than TB80 and higher thermal resistance than WO, respectively. The adhesive layers of work-piece material on the rake and flank faces of both TB20 and TB80 were much thinner than that of WO, which suggested a lower adhesive wear rate in TiB₂-B₄C cutting tools. The high wear resistance of TiB₂-B₄C cutting tools is attributed to higher thermal resistance, higher hardness, and lower chemical affinity with titanium as compared with tungsten carbides, which makes them very promising materials for high speed machining of titanium alloys.     

Investigation of machinability in milling of Inconel 718 with solid Sialon ceramic tool using supercritical carbon dioxide (scCO2)-based cooling conditions

Milling of hard-to-machining materials is still a challenge since the high cutting temperature caused by the cooling lubrication problems and the property of materials. This paper proposes the use of supercritical carbon dioxide (scCO₂), supercritical carbon dioxide based minimum quantity lubrication cutting fluid (scCO₂-MQL), and supercritical carbon dioxide based minimum quantity lubrication with oil droplets cutting fluid (scCO₂-OoW) as the eco-friendly cooling-lubrication methods for milling of Inconel 718 superalloy. The cutting forces, cutting temperatures, surface roughness, surface topographies, subsurface characteristics and tool wear were performed to quantify the effect of various cooling methods. The results indicated that the application of scCO₂-based cooling conditions was an effective cooling and lubrication technology for the ceramic tool since it could reduce the cutting force and temperature and improve the surface finish with lower peaks and valleys dispersion compared with other cooling conditions. Compared with the scCO₂-MQL, only scCO₂ and dry milling conditions, the topographies of machined surface under the scCO₂-OoW condition have been significantly improved. Furthermore, the scCO₂-OoW cooling technique has facilitated the removal of debris adhering to the ceramic tool and improved lubrication of the cutting zone.     

Reliability prediction of a microwave sintered Si3N4-based composite ceramic tool

The wear life reliability prediction model of microwave sintered Si₃N₄/(W,Ti)C/Y₂O₃/MgO/Al₂O₃ composite ceramic tools based on the random distribution characteristics of hardness and fracture toughness of ceramic tool material was established. It showed that the Vickers hardness of ceramic tool materials followed a normal distribution and the fracture toughness followed a lognormal distribution. Distribution law of wear life can be determined by the joint distribution of hardness and fracture toughness. Experimental research on tool reliability of continuous dry cutting quenched high quality carbon steel T10A was carried out and the applicability of the tool reliability prediction model was verified. The results showed that the error between the theoretical reliable life and the actual life of the ceramic tool was less than 5% under the same reliability when the reliability was above 0.5.     

Cutting performance and wear mechanisms of the graphene-reinforced Al2O3-WC-TiC composite ceramic tool in turning hardened 40Cr steel

The Al₂O₃-WC-TiC-graphene composite ceramic tool (AWTG0.5) fabricated by two-step hot pressing was used to continuously turn the hardened 40Cr steel at different cutting speeds, and its cutting performance and wear mechanisms were compared with the homemade graphene-free AWTG0 ceramic tool and the commercial ceramic tools SG4 and LT55. The cutting performance of the AWTG0.5 tool was significantly better than that of the AWTG0, SG4 and LT55 tools. The contributions of graphene to the mechanical properties, lubricating properties and thermal conductivity of the AWTG0.5 tool were responsible for its higher cutting performance. The main wear mechanisms of the AWTG0.5 tool were adhesive wear and abrasive wear. In addition, it was also found that the anti-friction and wear resistance performances of the AWTG0.5 tool were superior to those of the other three tools. Its good anti-friction and wear resistance performances could be attributed to the formation of a self-lubricating layer induced by graphene pull-out.     

Wear behavior of SiAlON ceramic tool and its effects during high-speed cutting

Nickel-based superalloys are widely employed in aerospace and other fields on account of excellent performance. However, the tool is easily worn out in cutting of superalloys, which will deteriorate the surface quality and lower the service life of the components. In this paper, the effect of ceramic tool wear on surface integrity during high-speed turning of superalloy GH4169 was studied. The results demonstrate that tool wear raises cutting temperature and cutting force. The wear mechanisms of the rake face of the ceramic tool are adhesive wear and oxidation wear, and the wear mechanisms of the flank face are adhesive wear, oxidation wear and abrasive wear. The enhancement effect of tool wear on thermal effect is greater than that on mechanical effect, which forms a larger tensile residual stress on the machined surface. In addition, tool wear increases the thickness of the plastic deformation layer, raising the KAM value from 0.43° to 0.63° at a cutting speed of 200 m/min.     

Investigation of novel multiscale textures for the enhancement of the cutting performance of Al2O3/TiC ceramic cutting tools

Currently, the high temperature and severe friction conditions at the tool-chip interface are the main reasons for ceramic tool wear failures. Surface texturing as a geometric extension for cutting tools is a promising way to extend their service life. In this study, a novel type of multiscale texture was developed, and its effect on the cutting performance of an Al₂O₃/TiC ceramic cutting tool while machining AISI H13 steel was explored in a conventional cooling environment. The cutting force, cutting temperature, and tool wear morphology were investigated at cutting velocities ranging from 80 to 249 m/min. Microgroove textured Al₂O₃/TiC ceramic tools were prepared for comparison. The results show that the structure of the multiscale textures maintained good integrity over the range of cutting velocities. Thus, the synergistic effect of the microscale and nanoscale textures promoted the introduction and permeation of the cutting fluid. Therefore, the multiscale textures effectively enhanced the cutting performance of the Al₂O₃/TiC ceramic tools.     

Fabrication and cutting performance of Ti(C,N)-based cermet tools used for machining of high-strength steels

Two kinds of Ti(C,N)-based cermet tools, namely TMWNC and TMWC, were fabricated for the machining of high-strength steels. This research investigated the cutting performances of both tools in terms of chip morphology, cutting force, cutting temperature, and tool wear and failure mechanisms. The results reveal that at the same cutting speed, the life of TMWC tool is longer than that of TMWNC tool with lower cutting force and higher cutting temperature than those of TMWNC tool. For TMWNC tool, at a lower cutting speed of 150 m/min, the tool failure is caused by abrasive wear. And when the cutting speed increases further, the surface flaking and nose breakage occur due to the comprehensive effects of adhesive wear, abrasive wear and thermal-mechanical fatigue. While for TMWC tool, the tool wear is severe with chipping, as a result of adhesive wear and abrasive wear. The research has proven the application feasibility of TMWNC and TMWC tools in the machining of high-strength steels. The TMWNC tool with higher fracture toughness presents better edge chipping resistance, and the TMWC tool with higher hardness and hot hardness exhibits better resistance against breakage.     

Friction and wear behavior of microwave sintered Al2O3/TiC/GPLs ceramic sliding against bearing steel and their cutting performance in dry turning of hardened steel

An Al₂O₃/TiC/GPLs (ATG) composite ceramic tool material was fabricated by microwave sintering. The tribological properties of ATG during sliding against GCr15 bearing steel were studied, to investigate the effects of sliding speed and normal load on the friction coefficient and wear rate. In addition, the cutting performance of ATG tools for machining of hardened alloy 40Cr steel was experimentally studied and compared with those of commercial tools. The results showed that the added graphene platelets enhanced the wear resistance and reduced the friction coefficient of the tool material. Furthermore, upon adding graphene platelets, the ability of the tools to resist breakage and their cutting depth improved. The cutting length of the microwave- sintered ATG ceramic tools was approximately 125% higher than that of hot-pressed ceramic tools and 174% higher than that of cemented carbide tools.     

Cutting performance and tool wear of SiAlON and TiC-whisker-reinforced Si3N4 ceramic tools in side milling Inconel 718

Cutting performance and tool wear of two ceramic tools, SiAlON and TiC-whisker-reinforced Si₃N₄, in the side milling processes of Inconel 718 are evaluated in comparison, including cutting force, temperature, surface morphology, tool wear and corresponding mechanism. Results show that these two ceramic tools has advantages and disadvantages respectively, due to the properties of ceramic matrixes and the evolutions of build-up edges. SiAlON ceramic tool has better resistance to wear, but causes poor surface quality. TiC-whisker-reinforced Si₃N₄ ceramic tool generates better surface quality, but bears severe wear. Brittle damage, as the main mode of wear, occurs to both ceramic tools in different formations. SiAlON ceramic tool is featured by crater-like damage on blades while TiC-whisker-reinforced Si₃N₄ ceramic tool is featured by whole-layer damage on flank faces.     

Performance evaluation of whisker-reinforced ceramic tools under nano-sized solid lubricants assisted MQL turning of Co-based Haynes 25 superalloy

Ceramics are widely used in machining of high temperature alloys i.e., Co-based Haynes 25 alloy due to its superior characteristics. The present paper is focused on the performance of whisker-reinforced ceramic cutting tool (WRCCT) under nano-sized solid lubricants dispersed in MQL (nanofluid-MQL) during turning of Co-based Haynes 25 alloy. The turning experiments were performed under several cutting environments (dry, base fluid MQL (BF-MQL), hBN based nanofluid MQL (hBN-NMQL), MoS₂ based nanofluid MQL (MoS₂-NMQL), graphite based nanofluid MQL Gr-NMQL) by varying cutting speed (200 and 300 m/min) and feed rate (0.1 and 0.15 mm/rev) values. Initially, the viscosity and thermal conductivity of nanofluids were evaluated and then the prepared nanofluids were used for machining experiments. The results reveal that the rate of increase in thermal conductivity coefficient relative to base cutting fluid was 11.90% in hBN-nanofluid, 16.29% in MoS₂-nanofluid and 14.12% in Gr-nanofluid. In terms of machining performance, on the one hand, the minimum surface roughness was obtained from Gr-NMQL assisted machining, on the other hand, the hBN-NMQL has been successful in limiting of notch wear and nose wear values. Compared to dry turning, the temperature was reduced up to 27.18% with hBN doped nanofluids, while it was 34.95% with MoS₂ doped nanofluids and 29.32% with graphene doped nanofluids.     

Si3N4陶瓷刀具在切削淬硬钢时的磨损行为

采用两种Ｓｉ２Ｎ４刀具在普通车床上对ＣｒＷＭｎ和４５钢进行切削试验，并用ＳＥＭ，ＥＤＡＸ，ＸＰＳ等方法对刀具的磨损进行分析。结果指出：试验的陶瓷刀具材料在切削不同淬硬钢时均存在最佳切削速度。在ＦＤ０１相比，ＦＤ０２陶瓷刀具有更佳的切削性能，最佳切削速度可提高７８％。在最佳速度以下切削，刀具侧面将发生粘着磨损；在最佳速度以上，则被加工材料产生微区熔化，导致材料大面积转移，发生剥层磨损，最佳速度以下切