| 1. |
|
|
| 2. |
- Can, Antionette
(creator_code:cre_t)
-
Polycrystalline cubic boron nitride material
- 2023
-
Patent (övrigt vetenskapligt/konstnärligt)abstract
- This disclosure relates to a polycrystalline cubic boron nitride, PCBN, material that includes a binder matrix material containing nitride compounds. The nitride compounds are selected from HfN, VN, and/or NbN.
|
|
| 3. |
- Turkevych, Dmytro, et al.
(författare)
-
HP-HT sintering, microstructure, and properties of B6O- and TiC-containing composites based on cBN
- 2015
-
Ingår i: Journal of Superhard Materials. - 1934-9408. ; 37:3, s. 143-154
-
Tidskriftsartikel (refereegranskat)abstract
- The article presents a study of the potential for the use of B6O superhard boron suboxide as a binder in composite materials with a low cBN content. Superhard B6O is characterized by higher mechanical properties than TiC widely used in commercial materials today. Composites containing 60 vol % cBN and different binder compositions that included B6O and TiC have been sintered in a toroid-type high-pressure apparatus at a pressure of 7.7 GPa in a temperature range from 1500 to 2000 A degrees C. The microstructure, phase and elemental composition of the sintered materials have been examined via electron microscopy and X-ray diffraction analysis. Mechanical properties have been analyzed via indentation techniques. The performance of the cutting tools produced from the sintered composites has been evaluated in turning hardened cold work tool steel.
|
|
| 4. |
- Agmell, Mathias, et al.
(författare)
-
Development of a simulation model to study tool loads in pcBN when machining AISI 316L
- 2018
-
Ingår i: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 96:5-8, s. 2853-2865
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents the development of a FE-simulation model to predict the mechanical stresses and thermal loads that a cutting tool of polycrystalline cubic boron nitride (pcBN) is subjected to, when machining AISI 316L. The serrated chip formation of AISI 316L has a major impact on the periodic loads acting on the cutting tool. Therefore, it is vital to correctly model this serrated chip formation. One of the major difficulties with FE-simulations of metal cutting is that the extreme deformations in the workpiece material, often leads to a highly distorted mesh. This paper uses the Coupled Eulerian-Lagrangian (CEL) formulation in Abaqus/Explicit, where the workpiece is modelled with the Eulerian formulation and the cutting tool by the Lagrangian one. This CEL formulation enables to completely avoid mesh distortion. To capture the chip serration process, the workpiece material is described with the Johnson-Cook damage model. The FE-simulation results are validated via comparison of the modelled cutting forces, chip serration frequency, and contact length against experimental ones.
|
|
| 5. |
- Agmell, Mathias, et al.
(författare)
-
Investigation of mechanical and thermal loads in pcBN tooling during machining of Inconel 718
- 2020
-
Ingår i: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 107, s. 1451-1462
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigates machining superalloy Inconel 718 with polycrystalline cubic boron nitride (pcBN) tooling both numerically and experimentally. Particular attention is given to mechanical and thermal stresses in the cutting tool arising from segmented chip formation and associated forces and temperatures. The temperature dependence of the mechanical properties of pcBN has been investigated and incorporated into a numerical model. In order to capture the dynamic loads due to a serrated chip formation, the Johnson–Cook damage model has been used. The extreme deformations during a machining process often results in a numerical difficulties due to a distorted elements. This paper uses the coupled Eulerian–Lagrangian (CEL) formulation in Abaqus/Explicit, where the workpiece is modelled with the Eulerian formulation and the cutting tool by the Lagrangian one. This CEL formulation enables to completely avoid mesh distortion. The finite element simulation results are validated via comparison of the modelled static and dynamic cutting forces and thermal loads induced into the cutting tool. The numerical model predicts a temperature of 1100–1200 ∘C at the cutting interface, which is in line with experimental determined data. The principal stresses at the rake up to 300 MPa are recorded, whereas higher level of stresses up to 450 MPa are found in the notch region of the tool, well correlated with experimental observation.
|
|
| 6. |
- Agmell, Mathias, et al.
(författare)
-
Modelling Subsurface Deformation in High Speed Machining of Inconel 718
- 2012
-
Konferensbidrag (refereegranskat)abstract
- Abstract in UndeterminedTraditionally, the development and optimization of the machining process with regards to the sub-surface deformation is done through experimental method which is often expensive and time consume. This paper presents the development of a FE-simulation model to predict the depth of sub-surface deformation induced in the high speed machining of Inconel 718 by use of whisker-reinforced ceramic tool. The effects of cutting parameters and geometry on sub-surface deformation will be simulated by developed FE model. In addition to FE model, the experimental study was made to validate the results of FE model. Characterization of sub-surface deformation produced under different machining parameters and tool conditions was made by EBSD and in the cutting and feed directions.
|
|
| 7. |
- Bjerke, Axel, et al.
(författare)
-
Machinability improvement by in-operando Tool Protection Layers through designed steel alloying : The case of manganese steel
- 2024
-
Ingår i: Journal of Materials Processing Technology. - 0924-0136. ; 330
-
Tidskriftsartikel (refereegranskat)abstract
- Improvements in machinability by alloying of the workpiece often adversely impact the end user properties of a material. For example, the common use of non-metallic inclusions can lead to improved tool life during turning or milling, but often adversely affects weldability, corrosion, and wear resistance. A cutting tool material meets kilometers of workpiece material during a machining operation. Hence elements in small quantities in the workpiece may insignificantly affect the end user properties but may have large effects on tool wear. One such effect is the formation of refractory and wear resistant reaction products between the workpiece and tool. Such reaction products forming on tool surfaces may lead to improved machinability. This paper proposes the use of small amounts of alloying to induce such a Tool Protection Layer. Additionally, the paper develops a computational framework for designed alloying which balances formation of Tool Protection Layers, its in-process retention, and the functional properties of the alloy. The method has been validated for a case of manganese steel. The calculations were validated first by a wide range of diffusion experiments. Then by industrial turning of cast alloys, by comparing one reference and two newly designed alloys based on the alloying concept. The alloy with 0.003 mol fractions of Al resulted in more than 3 times increase in tool life, due to in-operando formation of Al2O3 Tool Protection Layer. The designed manganese steel maintained its functional properties with respect to abrasive wear resistance and retained its ability to work harden.
|
|
| 8. |
- Bjerke, Axel, et al.
(författare)
-
On chemical interactions between an inclusion engineered stainless steel (316L) and (Ti,Al)N coated tools during turning
- 2023
-
Ingår i: Wear. - 0043-1648. ; 532-533
-
Tidskriftsartikel (refereegranskat)abstract
- Non-metallic inclusions offer one of the most effective routes for improving the machinability of steels. However, the wear-reducing mechanisms activated by such inclusions are not fully understood. The interactions are notoriously difficult to predict due to the wide variety of steel grades, cutting conditions, and tool materials employed in industry. The interaction between PVD (Ti,Al)N coated cemented carbide tools, non-metallic inclusions, atmospheric oxygen, and the stainless steel 316L in a turning operation is therefore investigated here as a case study. The study includes turning experiments, nanometer resolution microscopy, and thermodynamic calculations. The paper explains how not only too high a contact pressures hinder the formation of protective deposits at the tool edge, but also how too low a contact pressure leads to excessive wear. A range of conditions specified in this paper must therefore be met for the two observed protective non-metallic inclusions Mg1Al2O4 and Al2Ca2Si1O7 to be preferentially deposited on a tool. Hence the coating wear is experimentally investigated, explained, and a thermodynamic calculation method for predicting the protective or degenerative potential of a deposit on the coating is presented.
|
|
| 9. |
- Bjerke, Axel, et al.
(författare)
-
Onset of the degradation of CVD alpha-Al2O3 coating during turning of Ca-treated steels
- 2021
-
Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 477
-
Tidskriftsartikel (refereegranskat)abstract
- The ability to control the shape, distribution and composition of non-metallic inclusions has had an important impact on many aspects of steel making. One such impact is on the machinability. Ca-treatments have shown to be able to reduce the abrasiveness of oxide inclusions, improve chip-breaking and lead to formation of deposits that reduce tool wear. However, machining Ca-treated steels with Al2O3 coated cemented carbide tools has not been as advantageous as expected. This study investigates the mechanisms behind the anomalous wear of Al2O3 coatings when turning soft Ca-treated steels. Longitudinal turning tests at a range of speeds (vc = 100-600 m/min) show rapid localized degradation of the Al2O3 coating limited to the sliding zone. Detailed analysis of the degradation mechanisms was performed using scanning and transmission electron microscopy. The results demonstrate a presence of chemical interactions between the alumina coating and non-metallic inclusions. The interaction resulted in the formation of mainly calcium aluminates and partly alumina-magnesia spinel. In-operando infrared thermography measurements indicate cutting temperatures of 850-1000 degrees C. Thermodynamic calculations give that CaO and MgO readily reacts with Al2O3, while the reaction with CaS requires presence of additional oxygen at these cutting conditions. Additional turning experiments investigate the influence of oxygen by controlling the cutting environment by adding oxygen (compressed air) or removing oxygen (supply argon). These additional tests show that the presence of additional oxygen has a limited impact on the possible Ca-Al2O3 interaction. This demonstrat a potential for further machinability improvements by controlling the chemical interaction between Ca and Mg based non-metallic inclusions and alumina coatings.
|
|
| 10. |
- Bjerke, Axel, et al.
(författare)
-
Thermodynamic modeling framework for prediction of tool wear and tool protection phenomena in machining
- 2021
-
Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 484-485
-
Tidskriftsartikel (refereegranskat)abstract
- Chemical, oxidational and diffusional interactions between the tool, chip and cutting environment are known tool wear mechanisms in machining. However, the interaction between tool, coating, workpiece, coolant and atmospheric oxygen can, under favorable conditions, lead to formation of reaction products that retard tool wear. A method with the ability to predict theses interactions, would therefore enable a better control over tool life in machining. An attempt to create such a modelling framework is developed in this study. This method can predict the phase composition and the driving force for degradation and the formation of protective interaction products in the cutting zone. This modeling approach is applicable across cutting processes in which chemical, diffusional and oxidational wear are dominant or present. This framework has been applied to investigate the interactions occurring in the cutting zone during turning of a medium alloyed low-carbon steel (Hybrid Steel (R) 55). A range of degradation events are predicted, as well as the formation of a protective corundum (Al,Fe,Cr)(2)O-3 or spinel (Al, Fe,Cr)(3)O-4 film due to an interaction between the Al-alloyed steel and the environment. Validation of the modeling was performed by studying tool wear and reaction products formed when machining with ceramics, PcBN and coated carbide tooling. Inserts are studied by the use of scanning and transmission electron microscopy, after cutting tests were performed. Additional tests were performed in different environments (dry, argon and coolant). The results confirmed the model predictions of oxidation and diffusion wear as well as the formation of an (Al,Fe,Cr)(3)O-4 tool protection layer. Thus, the proposed thermodynamic framework seem promising to serve as a predictive instrument for the correct pairing of existing tool and workpiece combinations and cutting parameters, or for tailoring respective material compositions for intentional formation of a tool protection layer. As well as guidance on how to apply present and future kinetic models when concurrent interaction mechanisms are present. Which lead to a reduction and minimization of costly experimental machining tests.
|
|
