| 1. |
- A. B. Marçal, L., et al.
(författare)
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Spatially resolved structural and chemical properties of the white layer in machined Inconel 718 super alloy
- 2024
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Ingår i: Materials and Design. - 0264-1275. ; 239
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Tidskriftsartikel (refereegranskat)abstract
- Inconel 718 is one type of nickel-based alloy used for a large range of applications, including gas turbines and aeroengines components. Although mechanical and thermodynamic properties of this material have been deeply studied in the past years, a method able to investigate local properties of the thin white layer formed on the alloy surface after machining remains challenging. Here, a 90 nm X-ray beam is used to probe the local strain, crystal orientation, and chemical composition of grains in the white layer. Data reveals mosaicity induced by the tool during machining. The high spatial resolution, combined with crystal lattice sensitivity, shows that the average grain size is around 30 nm throughout the white layer, while the strain is anisotropic nearest to the surface. Results provide new insights on the basic properties of the white layer in super alloys, revealing important information about the impact of finish machining which might help to explain fatigue and cracking formation on these materials during their usage phase.
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| 2. |
- Bergs, T., et al.
(författare)
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Digital twins for cutting processes
- 2023
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Ingår i: CIRP Annals. - 0007-8506. ; 72:2, s. 541-567
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Tidskriftsartikel (refereegranskat)abstract
- Collecting and utilizing data in industrial production are becoming increasingly important. One promising approach to utilize data is the concept of digital twin (DT). DTs are virtual representations of physical assets, updated by real data and enhanced by models. This paper provides an overview of DTs for cutting processes. After giving a definition, we discuss requirements derived from representative use cases. As process models are central for DT creation, we present an overview of the latest research as well as conditions for how it can be implemented in industrial environments. The paper concludes with main challenges for future research.
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| 3. |
- Bushlya, V., et al.
(författare)
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Sintering of binderless cubic boron nitride and its modification by β-Si3N4 additive for hard machining applications
- 2020
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Ingår i: International Journal of Refractory Metals and Hard Materials. - : Elsevier BV. - 0263-4368. ; 86
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Tidskriftsartikel (refereegranskat)abstract
- This study present the results of HP-HT sintering, microstructure, properties, and performance of binderless cBN tool material. Within the investigated sintering temperature range of 1900–2600 °C the optimum was found to be 2200–2300 °C. Lower temperature results in incomplete diffusion bonding between cBN grains, while higher temperature results in high degree of recrystallization of initial structure, grain growth, and even formation of hexagonal boron nitride in triple joints. Introduction of stress-inducing β-Si3N4 minor inclusions resulted in high overall mechanical and thermal properties: HK = 41 GPa; KIC = 12.6 MPa·m1/2; λ = 180 W/(m·K). Machining experiments in roughing of hardened tool steels show that binderless cBN material provides high performance in terms of resistance to tool cratering, chipping, and tool fracture.
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| 4. |
- Chen, Z., et al.
(författare)
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Plastic Deformation and Residual Stress in High Speed Turning of AD730™ Nickel-based Superalloy with PCBN and WC Tools
- 2018
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Ingår i: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 71, s. 440-445, s. 440-445
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Konferensbidrag (refereegranskat)abstract
- A higher gas turbine efficiency can be achieved by increasing the operating temperature in hot sections. AD730™ is a recently-developed wrought/cast nickel-based superalloy which can maintain excellent mechanical properties above 700. However, machining of AD730™ could be a difficult task like other nickel-based superalloys. Therefore, studies are needed with respect to the machinability of this new alloy. In this paper, high-speed turning was performed on AD730™ using polycrystalline cubic boron nitride (PCBN) tools and coated tungsten carbide (WC) tools at varied cutting speeds. The surface integrity was assessed in two important aspects, i.e., surface and sub-surface plastic deformation and residual stresses. The PCBN tools generally showed better performance compared with the WC tools since it led to reduced machining time without largely compromising the surface integrity achieved. The optimal cutting speed was identified in the range of 200-250 m/min when using the PCBN tools, which gives rise to a good combination of machining efficiency and surface integrity. The further increase of the cutting speed to 300 m/min resulted in severe and deep plastic deformation. Meanwhile, a continuous white layer was formed at the machined surface. When turning with the WC tools, the increased cutting speed from 80 m/min to 100 m/min showed very little effect with respect to the plastic deformation on the machined surface. It was found that tensile residual stresses were developed on all machined surfaces no matter when the PCBN or WC tools were used, and the surface tension was generally increased with increasing cutting speed. The tensile layer might need to be modified by e.g., post-machining surface treatments such as shot peening, if taking good fatigue performance into consideration.
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| 5. |
- Courbon, Cedric, et al.
(författare)
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Adhesion tendency of PVD TiAlN coatings at elevated temperatures during reciprocating sliding against carbon steel
- 2015
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Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 330-331, s. 209-222
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Tidskriftsartikel (refereegranskat)abstract
- This work focussed on assessing the contact conditions driving the adhesion tendency of PVD TiAlN coated cemented carbide during reciprocating sliding against a normalized AISI 4137 carbon steel. A special emphasis is given to the surface topography of the coating. Results are analysed in terms of friction and material transfer over a large range of temperatures (up to 800 °C) and contact pressures. The post-test surface analysis of the specimens is conducted in order to understand the tribological behaviour and elucidate the formation mechanisms of transfer layers. A numerical model is developed to assess the amount of heat effectively transmitted into the first bodies and the temperature of the surfaces in contact.Whereas temperatures close to 400 °C ensure the formation of a stable tribofilm reducing friction, the highest temperatures lead to unstable frictional behaviour. Coating surface topography has been seen to be a major parameter driving material transfer during the first stages of the contact and the formation of a transfer layer. Thin and homogeneous layers are almost instantaneously formed with a polished surface whereas some time is required with a rougher one to form a film. A large amount of the frictional power is dissipated into these layers and high temperatures can be reached at the surface due to frictional heating. Contact pressure is found to be a parameter promoting transfer and oxidation
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| 6. |
- Fallqvist, Mikael, 1982-, et al.
(författare)
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Mechanical and tribological properties of PVD-coated cemented carbide as evaluated by a new multi-pass scratch testing method
- 2012
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Ingår i: Advances in Tribology. - : Hindawi Limited. - 1687-5915 .- 1687-5923. ; 2012, s. 305209-
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Tidskriftsartikel (refereegranskat)abstract
- A new test method based on multi-pass scratch testing has been developed for evaluating the mechanical and tribological properties of thin, hard coatings. The proposed test method uses a pin-on-disc tribometer and during testing a Rockwell C diamond stylus is used as the “pin” and loaded against the rotating coated sample. The influence of normal load on the number of cycles to coating damage is investigated and the resulting coating damage mechanisms are evaluated by post-test scanning electron microscopy. The present study presents the test method by evaluating the performance of Ti0.86Si0.14N, Ti0.34Al0.66N and (Al0.7Cr0.3)2O3 coatings deposited by cathodic arc evaporation on cemented carbide inserts. The results show that the test method is quick, simple and reproducible and can preferably be used to obtain relevant data concerning the fatigue, wear, chipping and spalling characteristics of different coating-substrate composites. Also, the small size of the test region (the radius of the circular scratch track can be as small as 0.5 mm) makes it possible to perform tests within small restricted areas. Consequently, the test method can be used as a virtually non-destructive test and e.g. be used to evaluate the fatigue and wear resistance as well as the cohesive and adhesive interfacial strength of coated cemented carbide inserts prior to cutting tests.
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| 7. |
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| 8. |
- Gordon, S., et al.
(författare)
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Mechanical integrity of PVD TiAlN-coated PcBN : Influence of substrate bias voltage and microstructural assemblage
-
Ingår i: Ceramics International. - 0272-8842.
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Tidskriftsartikel (refereegranskat)abstract
- Polycrystalline cubic boron nitrides (PcBN) have been increasingly used together with PVD coatings, mainly for hard turning operations. Within this context, effectiveness of coated PcBN as cutting tool is usually addressed by evaluation of its machining performance. Meanwhile, studies aiming to assess and understand the correlation between microstructural features and mechanical behaviour of the coating-substrate system are rather limited. Aiming to overcome such lack of information, in this study the influence of substrate bias voltage (−35 V as compared to −60 V) and microstructural assemblage (as a function of cBN content and binder chemical nature) on the mechanical integrity of TiAlN-coated PcBN systems is investigated. In doing so, contact damage response and coating adhesion strength of different coated-PcBNs are evaluated by means of indentation testing using distinct loading conditions (static and sliding) and tip geometries (spherical and conical). Such testing program is complemented by detailed FESEM inspection of the involved failure micromechanisms, as well as microstructural and micromechanical characterization of the deposited films. Results indicate that resistance against crack nucleation and propagation of coated PcBN, induced by either spherical or conical indentation, is enhanced by using harder (high content of cBN particles) and tougher (metallic binder) substrates (H-PcBN). Regarding bias voltage, systems with coatings deposited using a higher value (−60 V as compared to −35 V) show improved adhesive strength, this being particularly true for combinations involving low cBN content and ceramic binder substrate (L-PcBN). Similar beneficial effect was found, but exclusively in coated L-PcBN systems, regarding resistance to radial cracking emergence and to material removal through cohesive-failure chipping induced in Rockwell C tests. Although these findings are linked to the higher compressive residual stresses exhibited by coatings deposited under −60 V bias voltage, the latter does not translate in significant changes in microstructural and intrinsic mechanical properties of the TiAlN coating itself.
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| 9. |
- Kryzhanivskyy, V, et al.
(författare)
-
An inverse problem for retrieving time dependency of heat flux in metal cutting via linear programming
- 2018
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Ingår i: Procedia Manufacturing. - : Elsevier BV. - 2351-9789. ; 25, s. 287-293
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Tidskriftsartikel (refereegranskat)abstract
- The paper addresses the inverse heat transfer problem, in which the dependence of the flux on time is determined on the basis of the measured temperatures in remote points of the tool body. The nonlinear heat equation is considered since the properties of the tool material are temperature-dependent. The machining time interval is divided into subintervals within which the change in the tool material properties is ignored. Therefore, it possible to consider a sequence of linear programming problems, each of which minimizes the maximum deviation of the measured temperatures from the calculated ones.
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| 10. |
- Kryzhanivskyy, V., et al.
(författare)
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Experimental study and modeling of the heat flux acting on the tool flank when machining
- 2021
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Ingår i: 18th CIRP Conference on Modeling of Machining Operations (CMMO), Ljubljana, Slovenia, June 15-17, 2021. - : Elsevier BV. - 2212-8271. ; 102, s. 97-102
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Konferensbidrag (refereegranskat)abstract
- Adequate setting of the boundary conditions for the heat equation when modeling the temperature distribution in the cutting tool is one of the key points. The boundary conditions on the tool surfaces can be divided into two groups: conditions that describe heat losses (heat exchange with the environment) and conditions that characterize the heat source that heats up the tool (heat flux from the cutting zone). Additional complexity in modeling is provided by the fact that during cutting the surface on which the heat source acts changes, for example, due to wear on the flank surface. In this paper, a method is proposed for measuring the power of a heat source acting on the flank surface. The hardware of the method includes a sensor equipped tool and specially manufactured inserts that imitate the geometry of worn flank surface. In turn, the software is based on the method of solving the inverse heat conduction problem in metal cutting, which allows restoring the heat flux flowing into the tool by measuring temperature with sensors installed in the toolholder. The experimental plan included inserts with negative and positive rake, different cutting speeds (190, 235, 280 m/min), and feeds (0.15, 0.3, 0.45 mm/rev).
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| 11. |
- Kryzhanivskyy, V., et al.
(författare)
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Heat flux in metal cutting : Experiment, model, and comparative analysis
- 2018
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Ingår i: International Journal of Machine Tools and Manufacture. - : Elsevier BV. - 0890-6955. ; 134, s. 81-97
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a proof of time-dependent behavior of heat flux into a cutting tool is built. Its implementation calls for a new method for estimating heat flux, which was developed using an inverse problem technique. A special experimental setup was designed and manufactured to implement the method. A series of dry machining experiments were conducted with high speed steel and cemented carbide tooling. A two-stage procedure was developed to overcome the ill-posedness of the inverse heat conduction problem by transforming it into a well-posed parameter estimation problem. The first stage retrieves the value of the heat flux and specific tool heating energy Et. The second stage parametrizes and compares predefined heat flux behaviors. It was found that the time dependency of heat flux is best described by a decreasing power function.
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| 12. |
- Kryzhanivskyy, V., et al.
(författare)
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Influence of tool material and tool wear on tool temperature in hard turning reconstructed via inverse problem solution
- 2017
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Ingår i: Journal of Superhard Materials. - 1063-4576. ; 39:3, s. 192-202
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Tidskriftsartikel (refereegranskat)abstract
- In this work the cutting tool temperature distribution that develops during turning of hardened cold-work tool steel is modeled on the basis of experimental data. The data obtained from a series of thermocouples, placed on a PCBN insert, into an anvil, and into a toolholder, were used as the input for the model. An inverse problem was solved, where the heat fluxes were computed. The temperature distribution was modeled for the case of new tools, as well as for the case of its development in the course of a tool wear. The reconstructed temperature distributions were in good agreement with the measured data. The heat flux through rake face was found to be reducing with the decrease of thermal conductivity of the tool material.
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| 13. |
- Kryzhanivskyy, V., et al.
(författare)
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Machine Learning based Approach for the Prediction of Surface Integrity in Machining
- 2022. - C
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Ingår i: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 108, s. 537-542
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Konferensbidrag (refereegranskat)abstract
- This paper presents a two-stage procedure to create a surface integrity predictor. The first stage includes data clustering, which allows to evaluate the achievable surface quality. The second stage consists in training the model to predict which cluster the machined surface will belong to. To demonstrate the applicability, an experimental plan for machining of Inconel 718 in milling was developed. The validation through confusion matrix showed that the accuracy of prediction ranged from 64.7% to 84.9% for different test and train sets. Prospect of the research is to expand the set of monitored machining parameters and controlled surface integrity parameters.
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| 14. |
- Malakizadi, Amir, 1983, et al.
(författare)
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Post-processing of additively manufactured metallic alloys – A review
- 2022
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Ingår i: International Journal of Machine Tools and Manufacture. - : Elsevier BV. - 0890-6955 .- 1879-2170. ; 179
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Forskningsöversikt (refereegranskat)abstract
- Additive manufacturing (AM) is characterised by several unique advantages, such as (freedom of) design, capability of fusing dissimilar materials, near-net-shape, and achieving a more sustainable production. While the increased precision of metal AM in recent years reduced the needed amount of post-processing to meet dimensional tolerance, the requirements for functional surfaces necessitate a well-understood post-processing, ranging from heat treatment to machining and finishing. The inherently rough initial (as-built) surface topography next to complex material microstructure affects the capability of post-processing/finishing operations to smooth the surface texture and obtain a favourable surface integrity. In this respect, a more fundamental understanding of the effects of material properties on post-processing/finishing is needed. Therefore, this review paper aims to establish the relationship between the characteristics of different AM technologies, microstructural properties of materials in as-built and heat-treated conditions, and the physical properties influencing the response of additively manufactured materials during post-processing/finishing operations. In particular, emphasis is placed on the physics-based understanding of how the microstructural characteristics of 316L, Ti6Al4V and Alloy 718 produced using the two principal technologies, Powder Bed Fusion (PBF) and Direct Energy Deposition (DED), influence their mechanical properties like tensile strengths, hardness and ductility. These properties are among the key factors influencing the response of material during post-processing/finishing operations involving material removal by shear deformation. This review paper also discusses the role of post-processing/finishing on fatigue performance, tribological behaviour and corrosion resistance of investigated AM materials. The paper summarises the state-of the art of post-processing/finishing operations and future research trends are highlighted.
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| 15. |
- M'Saoubi, R., et al.
(författare)
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Experimental study and modelling of tool temperature distribution in orthogonal cutting of AISI 316L and AISI 3115 steels
- 2011
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Ingår i: The International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 56, s. 865-877
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Tidskriftsartikel (refereegranskat)abstract
- Cutting tool temperature distribution was mapped using the IR-CCD technique during machining of carbon steel AISI 3115 and stainless steel AISI 316L under orthogonal cutting conditions using flat-face geometry inserts. The effect of work material treatment on tool temperature was investigated, and the results showed that AISI 3115 in heat-treated state displayed higher tool temperature than the as-rolled state. Stainless steel 316L with high sulphur content (0.027 wt.%) and calcium treatment displayed lower cutting tool temperature than the variant with low sulphur (0.009 wt.%). The experimental results were compared with theoretical tool temperature distributions based on a modified version of Komanduri and Hou's analytical model. In particular, variable frictional heat source and secondary shear were introduced and modelling of the tool stress distribution on rake surface was also considered. © 2011 Springer-Verlag London Limited.
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| 16. |
- MSaoubi, R., et al.
(författare)
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Microstructure and wear mechanisms of texture-controlled CVD alpha-Al2O3 coatings
- 2017
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Ingår i: Wear. - : ELSEVIER SCIENCE SA. - 0043-1648 .- 1873-2577. ; 376, s. 1766-1778
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, the microstructure and wear mechanisms of texture controlled CVD alpha-Al2O3 layers with (001), (012) and (100) growth textures were investigated in single point turning of C45 carbon steel at low and high cutting speeds. The experimental coatings were investigated by FEG-SEM, EBSD and a combination of FIB and analytical TEM techniques prior to and after machining. Significant texture effects on wear performance of the alpha-Al2O3 coating layers were observed, confirming results from previous wear studies in the context of machining AISI 4140 carbon steel. The wear mechanisms of the coating layers were further interpreted in the light of thermal, mechanical and frictional conditions occurring at the tool chip contact interface. Possible deformation mechanisms of the alpha-Al2O3 layers under the conditions of high pressure and temperatures acting on the tool surface are discussed. The high dislocation density revealed by the TEM observations in the subsurface alpha-Al2O3 layers was attributed to the activation of a basal slip deformation mechanism resulting from the combined action of the shear stress field and high temperature acting on the tool surface. It is suggested that the enhanced and more uniform near surface deformation capability of (001) alpha-Al2O3 is responsible for the improved machining performance. (C) 2017 Elsevier B.V. All rights reserved.
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| 17. |
- M'Saoubi, R, et al.
(författare)
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Wear mechanisms of PVD-coated PCBN cutting tools
- 2013
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Ingår i: Wear. - : Elsevier. - 0043-1648 .- 1873-2577. ; 302:1-2, s. 1219-1229
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Tidskriftsartikel (refereegranskat)abstract
- The wear characteristics of PVD coated (TiN, TiSiN, TiAlN, and AlCrN) polycrystalline cubic boron nitride (PCBN) cutting tools were compared to those of uncoated PCBN during single point turning of case hardened steel 16MnCr5. Post-cutting observations of the worn inserts were performed using high resolution field emission gun scanning electron microscope (FEG-SEM) in combination with focus ion beam (FIB) and analytical transmission electron microscopy (TEM). Substantial differences in the wear behaviour of the different coating materials could therefore be observed. In particular, a remarkable tendency for TiN to exhibit plastic deformation was revealed while TiSiN exhibited a more brittle behaviour evidenced by adhesive wear and microchipping. TiAlN and AlCrN on the other hand exhibited less workpiece adhesion. The wear mechanisms of the above thin coating layers are discussed and interpreted in light of thermal, mechanical, and frictional conditions occurring at the tool-chip contact.
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| 18. |
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| 19. |
- von Fieandt, Linus, et al.
(författare)
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Chemical Interactions Between Cemented Carbide and Difficult-to-Machine Materials by Diffusion Couple Method and Simulations
- 2018
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Ingår i: Journal of phase equilibria and diffusion. - : SPRINGER. - 1863-7345 .- 1547-7037. ; 39:4, s. 369-376
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Tidskriftsartikel (refereegranskat)abstract
- A simple and efficient diffusion couple method is utilized to study the chemical interactions between cemented carbide cutting tools and difficult-to-machine materials (Ti, Ti-6Al-4V, Ni, Inconel 718, Fe, and AISI 316L). The experimental results and simulations probe different chemical interactions between the cemented carbide and work materials. In particular, the formation of a thick TiC layer is observed at the cemented carbide/Ti and Ti-6Al-4V interface while eta-phase is formed at the interface between the cemented carbide and work materials Inconel 718, Fe and AISI 316L. Pure titanium and Ti-6Al-4V both interact strongly with the tool causing formation of TiC and dissolution of WC-grains. Experiments and diffusion simulations confirm bcc-W formation and progressive diffusion of W into bcc-Ti. For both Ti and Fe work materials a dense band of carbides (WC + eta or WC + TiC) forms at the interface, effectively inhibiting further diffusion. Ni does not form any stable carbide and lowers the eta-phase limit in terms of carbon content, wherefore diffusion can occur freely. The diffusion couple method used in this work, corroborated by DICTRA simulations should serve as a useful tool in the detailed analysis of worn tools where chemical wear is dominant.
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| 20. |
- Zhou, J. M., et al.
(författare)
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Surface Characterization of AD730TM Part Produced in High Speed Turning with CBN tool
- 2018
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Ingår i: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 71, s. 215-220, s. 215-220
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Konferensbidrag (refereegranskat)abstract
- AD730TM is a novel superalloy developed for the hot section part in aero engine and gas turbine machinery with enhanced performance. The material is characterized by its excellent high temperature properties for being an alloy possible to manufacture by cast and wrought process compared to other superalloys in the same class such as Inconel718. The material with higher temperature capability means potentially increased energy efficiency as well as less emission in the new engine design. However, there is lack of information on machinability of the material, especially achievable surface quality under high speed machining. Machining process is commonly employed in the manufacturing of hot section part, such as turbine disc, to obtain the final surface quality and tolerance. Surface quality produced by the machining processes is one of the crucial factors to determine the functional performance and correspondent fatigue life time of the parts. The paper will present the results of surface characterization of the part produced by high speed turning with CBN tool. A series machining tests were conducted in the study. Surface morphology on machined samples were investigated with a scanning electron microscope to assess the surface damages and other surface defects induced by the machining processes. 3D surface topology was also analyzed with an Infinite-focus-variant microscope to correlate with machining condition. In addition, effect of tool wear and cutting parameters, such as cutting speed, will also be discussed in the paper.
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