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Machinability and Tribological Performance of Advanced Alloys
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Machinability and Tribological Performance of Advanced Alloys

A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Metal Failure Analysis".

Deadline for manuscript submissions: closed (1 May 2023) | Viewed by 41361

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editor

Dr. George A. Pantazopoulos

E-Mail Website1 Website2
Guest Editor
ELKEME Hellenic Research Centre for Metals S.A, Oinofyta Viotias, Greece
Interests: failure analysis; fracture analysis; fractography; fracture mechanics; mechanical behavior of materials; metallography; scanning electron microscopy; manufacturing technology; materials processing; machinability; surface engineering; corrosion; tribology; quality assurance; design of experiments
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Machining constitutes one of the most significant categories of manufacturing processes, dedicated in final component production, including also special, precision parts and difficult-to-machine materials. The challenging aspects of this topic arise from the continuously evolving quality and productivity requirements in modern industry, together also with the innovative aspects of new and smart materials in combination with the energy and environmental (green/clean) regulations imposed in industry. In general, among conventional machining operations, high-end modern material removal processes are also included in the subject of the Special Issue (e.g., using high-energy beams such as laser machining).

The tribological performance of alloys plays an important role in the production or service environment, which is closely related to their manufacturing characteristics, and it is therefore considered as a combined topic in the frame of this Special Issue. The study of tribological behavior more diligently addresses the surface engineering aspects of modern and conventional alloys, either in bulk or in coating form, in a more generic context of industrial component production and endurance in a severe working environment.

The core subject of this Special Issue is the elaboration and presentation of studies focusing on the alloy design, manufacturing, testing, and characterization in order to provide a clear insight on the machinability and/or tribological behavior. Improvement of these closely adherent properties has led to the development of new alloy chemistries, novel engineered microstructures, and the application of coatings that lead to higher machinability and/or tribological endurance under aggressive service conditions. The environmental and health and safety regulations demand the use of ecofriendly components where human health and safety is compulsory. The manufacture of antimicrobial copper alloys in healthcare facilities and the elimination of lead in brass components for drinking water applications constitute representative examples, showing the modern industrial trends.

The optimization of machinability and tribological performance, altering also the manufacturing and service conditions, is also another core subject in this topic. The application of surface processes to enhance the tribological performance of the alloys is also a challenging topic to be addressed in this Special Issue. This Special Issue aims to gather and disseminate research knowledge in the most recent advances, collecting original high-quality papers in the field of the machinability and tribological performance of advanced alloys.

This Special Issue also welcomes papers from conference works, such as International Conference of Engineering Against Failure (ICEAF VI) and the 13th International Conference of Mechanical and Aerospace Engineering 2022 (13th ICMAE 22), to be held in Bratislava, 20-22 July 2022. For more information please visit https://iceaf.eu/2021/publication_policy and http://www.icmae.org/.

Dr. George A. Pantazopoulos
Guest Editor

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Machinability
  • Ecofriendly alloys
  • Antimicrobial alloys
  • Novel and conventional machining processes
  • Optimization of machining parameters
  • Tribological behavior of alloys
  • Tribological behavior of coatings
  • Manufacturing of machinable alloys
  • High wear resistance alloys and coatings
  • Nanostructured coatings

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Published Papers (16 papers)

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Editorial

Jump to: Research, Review

5 pages, 534 KiB  
Editorial
Machinability and Tribological Performance of Advanced Alloys
by George A. Pantazopoulos
Metals 2023, 13(7), 1190; https://doi.org/10.3390/met13071190 - 27 Jun 2023
Viewed by 1115
Abstract
Machining is specially utilized to manufacture special, precision parts and difficult-to-form materials. Full article
(This article belongs to the Special Issue Machinability and Tribological Performance of Advanced Alloys)
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Research

Jump to: Editorial, Review

24 pages, 12580 KiB  
Article
Evaluating Surface Quality of Inconel 617 by Employing Deep Cryogenically Treated Electrodes in Surfactant-Added Dielectrics of Transformer Oil
by Kashif Ishfaq, Muhammad Sana, Muhammad Arif Mahmood, Saqib Anwar and Muhammad Umair Waseem
Metals 2023, 13(6), 1092; https://doi.org/10.3390/met13061092 - 9 Jun 2023
Cited by 6 | Viewed by 1373
Abstract
Over the past few decades, better surface quality has remained of great interest to researchers. It deteriorates the fatigue life of the workpiece. The criticality arises when a material of greater strength is selected to work in high-temperature areas such as nickel (Ni)-based [...] Read more.
Over the past few decades, better surface quality has remained of great interest to researchers. It deteriorates the fatigue life of the workpiece. The criticality arises when a material of greater strength is selected to work in high-temperature areas such as nickel (Ni)-based superalloys, categorically Inconel 617. Conventional machining operations are not the best choice for the machining of this alloy because of its low density and greater strength. Therefore, electric discharge machining (EDM) is generally engaged. Still, there is a great necessity to make a more reliable surface using EDM, which performs better even in harsh working areas. Therefore, this study examined the potential of deep-cryogenically treated electrodes under the modified dielectrics of transformer oil in the said context, which has not been discussed so far. A set of 30 experiments was performed, designed using the full factorial technique. Deep-cryogenically treated electrodes provided better surface quality in comparison to the non-treated electrodes. Amongst the deep-cryogenically treated electrodes, brass performed outstandingly and provided the lowest value of surface roughness (SR), 6.65 µm, in the modified dielectric of transformer oil with Span 80. The surface finish of deep-cryogenically treated brass is 28.72% better compared to the average value of the overall deep-cryogenically treated electrodes. The lowest value of SR (8.35 µm) was gained by engaging a non-cryogenically treated Cu electrode with a T-20–transformer oil-modified dielectric. The said value of SR is 17.7% better than the highest value of SR achieved in the case of S-80–transformer oil with a non-cryogenically treated Cu electrode. Full article
(This article belongs to the Special Issue Machinability and Tribological Performance of Advanced Alloys)
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16 pages, 11634 KiB  
Article
Inverse Thermal Analysis as a Tool for Optimizing Concentrated Solar Energy Elaboration of Wear Resistant Surface Layers
by Anna D. Zervaki, Samuel G. Lambrakos, Athanasios G. Mourlas, Ioannis G. Papantoniou, José Rodríguez and Pandora P. Psyllaki
Metals 2023, 13(5), 942; https://doi.org/10.3390/met13050942 - 12 May 2023
Cited by 1 | Viewed by 1128
Abstract
Concentrated Solar Energy (CSE) processing is considered a promising renewable energy source technique for elaborating thick, wear-resistant claddings onto metallic surfaces of large dimensions that are expected to operate in heavy duty applications, such as excavator shovels, mineral crushers, etc. However, the prediction [...] Read more.
Concentrated Solar Energy (CSE) processing is considered a promising renewable energy source technique for elaborating thick, wear-resistant claddings onto metallic surfaces of large dimensions that are expected to operate in heavy duty applications, such as excavator shovels, mineral crushers, etc. However, the prediction of surface processing effects on the microstructure and the properties of the main construction base metal are of crucial importance, as they are commonly required in all surface modification techniques. Thus, the present study is focused on the inverse thermal analysis and parametric modeling of heat deposition associated with CSE surface processing of metals. In this preliminary attempt, experimental findings that concern the elaboration of TiC- and chromium carbide-reinforced clads onto common steel base metals were used to quantify the evaluation of the temperature histories within the volume of workpieces undergoing solar heating, where direct temperature measurements contain uncertainties and/or are not even possible. Results of prototype inverse thermal analyses of heat transfer in processed layer-substrate systems are presented, demonstrating the general aspects of a parametric model for thermal analysis and simulation. Full article
(This article belongs to the Special Issue Machinability and Tribological Performance of Advanced Alloys)
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22 pages, 10360 KiB  
Article
Effect of Wear on Vibration Amplitude and Chip Shape Characteristics during Machining of Eco-Friendly and Leaded Brass Alloys
by Peter Pavol Monka, Katarina Monkova, George A. Pantazopoulos and Anagnostis I. Toulfatzis
Metals 2023, 13(5), 828; https://doi.org/10.3390/met13050828 - 23 Apr 2023
Cited by 2 | Viewed by 1511
Abstract
The dynamic stability of the machining set and the entire cutting process, together with the appropriate form of chips generated during machining under the given conditions, are the basic prerequisites for autonomous machining in accordance with the Industry 4.0 trend. The research, based [...] Read more.
The dynamic stability of the machining set and the entire cutting process, together with the appropriate form of chips generated during machining under the given conditions, are the basic prerequisites for autonomous machining in accordance with the Industry 4.0 trend. The research, based on a newly designed method, aims to study the frequency response of the machining system to different values of tool wear and cutting speed, which cause the worsening of the machined parts’ quality and the instability of the whole cutting process. The new idea is based on the inverse principle, in which the wear with various values of VB was artificially prepared in advance before machining. Consequently, the effect of artificial wear and cutting speed on vibration and chip shape characteristics were studied. Three types of brass alloys were used within the experiments as the machined materials. Measured data were statistically processed and the desired dependencies were plotted. Chips were collected for each combination of machining conditions, while the article presents a database of the obtained chip shapes at individual cutting speeds so that they can be compared and classified. The results showed that brass alloys CW510L and CW614N exhibit an average of three times lower vibration damping compared to the CW724R alloy, while relatively good chip formation was noted in the evaluated machining conditions even without the use of a chip breaker. The problematic chip shape occurred only in some cases at the machining of CW510L and CW724R, which cannot be generalized. Full article
(This article belongs to the Special Issue Machinability and Tribological Performance of Advanced Alloys)
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16 pages, 4769 KiB  
Article
Assessment of the Effect of Thermal-Assisted Machining on the Machinability of SKD11 Alloy Steel
by Thi-Bich Mac, The-Thanh Luyen and Duc-Toan Nguyen
Metals 2023, 13(4), 699; https://doi.org/10.3390/met13040699 - 3 Apr 2023
Cited by 10 | Viewed by 1873
Abstract
This study aimed to investigate the effects of Thermal-Assisted Machining (TAM) on SKD11 alloy steel using titanium-coated hard-alloy insert cutting tools. The microstructure, material hardness, chip color, cutting force, chip shrinkage coefficient, roughness, and vibration during TAM were evaluated under uniform cutting conditions. [...] Read more.
This study aimed to investigate the effects of Thermal-Assisted Machining (TAM) on SKD11 alloy steel using titanium-coated hard-alloy insert cutting tools. The microstructure, material hardness, chip color, cutting force, chip shrinkage coefficient, roughness, and vibration during TAM were evaluated under uniform cutting conditions. The machining process was monitored using advanced equipment. The results indicated that thermal-assisted processing up to 400 °C did not alter the microstructure and hardness of the SKD11 alloy steel. However, a significant variation in chip color was observed, indicating improved heat transfer through TAM. The cutting force, vibration amplitude of the workpiece, and surface roughness all decreased with increasing TAM. Conversely, the chip shrinkage coefficient of the machined chips tended to increase due to the high temperatures. Full article
(This article belongs to the Special Issue Machinability and Tribological Performance of Advanced Alloys)
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13 pages, 3480 KiB  
Article
Tribological Behaviors of Inconel 718–Tungsten Carbide Friction Pair with Sulfur Additive Lubrication
by Ye Yang, Hao Luan, Songshan Guo, Fengbin Liu, Yuanjing Dai, Chenhui Zhang, Duzhou Zhang and Gang Zhou
Metals 2022, 12(11), 1841; https://doi.org/10.3390/met12111841 - 28 Oct 2022
Cited by 5 | Viewed by 1423
Abstract
This work investigated the lubricating and anti-wear properties of several sulfur additives for a nickel-based superalloy–tungsten carbide friction pair. Compared with PAO40 without any active chemical compounds, the three kinds of sulfur additives could decrease the friction coefficient from 0.2 to 0.1 and [...] Read more.
This work investigated the lubricating and anti-wear properties of several sulfur additives for a nickel-based superalloy–tungsten carbide friction pair. Compared with PAO40 without any active chemical compounds, the three kinds of sulfur additives could decrease the friction coefficient from 0.2 to 0.1 and the wear volume by 90%. Sulfurized fatty acid ester had the best performance under high temperature and heavy load with COF below 0.1 and the smallest wear volume. Furthermore, the lubricating mechanism was investigated by XPS. The physical adsorptive film and the tribochemical film together enhanced the friction-reducing and anti-wear performances of the lubricants. This effective lubricant for Inconel 718 can be applied to the machining of nickel-based alloy. Full article
(This article belongs to the Special Issue Machinability and Tribological Performance of Advanced Alloys)
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18 pages, 12799 KiB  
Article
Effect of Machining Conditions on Temperature and Vickers Microhardness of Chips during Planing
by Peter Pavol Monka, Katarina Monkova, Martin Vasina, Milena Kubisova, Martin Korol and Adriana Sekerakova
Metals 2022, 12(10), 1605; https://doi.org/10.3390/met12101605 - 26 Sep 2022
Cited by 2 | Viewed by 2100
Abstract
For the machining of long and narrow surfaces and when processing multiple pieces, planing technology is used, the productivity of which can be higher than that of milling, although it is relatively slow machining. The article aims to study the degree of influence [...] Read more.
For the machining of long and narrow surfaces and when processing multiple pieces, planing technology is used, the productivity of which can be higher than that of milling, although it is relatively slow machining. The article aims to study the degree of influence of the geometry of the tool (the angle of cutting-edge inclination and the angle of the tool-orthogonal rake), as well as the cutting conditions (cutting depth and cutting speed) on the chip characteristics (temperature and microhardness) in orthogonal and oblique slow-rate machining of steel 1.0503 (EN C45). The experiments were carried out on specially prepared workpieces designed for immediate stopping of machining. The results of the experiments were statistically processed, and behavioural models were created for temperature and Vickers microhardness of chips for individual combinations of factors. The obtained dependencies revealed how the geometry of the cutting tool and the cutting conditions affect the temperature and microhardness in the cutting area and at the same time allowed the best conditions for both orthogonal and oblique machining to be set up. Full article
(This article belongs to the Special Issue Machinability and Tribological Performance of Advanced Alloys)
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16 pages, 4532 KiB  
Article
Research of Resistance of Selected Materials to Abrasive Wear to Increase the Ploughshare Lifetime
by Monika Vargova, Miroslava Tavodova, Katarina Monkova and Miroslav Dzupon
Metals 2022, 12(6), 940; https://doi.org/10.3390/met12060940 - 30 May 2022
Cited by 14 | Viewed by 2822
Abstract
Road maintenance and cleaning in winter are performed with ploughshares. Due to the fact that the layer of snow and ice that is removed from the road surface contains various hard impurities, ploughshares are exposed to high intensity abrasive wear. This article deals [...] Read more.
Road maintenance and cleaning in winter are performed with ploughshares. Due to the fact that the layer of snow and ice that is removed from the road surface contains various hard impurities, ploughshares are exposed to high intensity abrasive wear. This article deals with the resistance to abrasive wear of originally used ploughshare materials and the materials that were designed as a suitable modification of the ploughshare to increase its service life. The chemical composition of materials used to manufacture ploughshare components is unknown. For this reason, they were analyzed with an ARL 4460 spectrometer, which was used to analyze the element content. The main part of the research was focused on the abrasion resistance test, which was performed according to the GOST 23.208-79 standard. Based on the chemical analysis, it was found that the basic body of the ploughshare was made of S355J2G3 steel, and the raking blade material was made of 37MnSi5 steel. The original material (steel S355J2G3) of the ploughshare body as a reference standard was compared to steel HARDOX 450. Furthermore, a sample made of the original material of the raking blade (steel 37MnSi5) was used as a reference standard, the properties of which were compared to the newly designed OK 84.58 and UTP 690 hardfacing materials. The parametric test method of statistical hypotheses was also used to process and evaluate the weight losses of the selected materials. Full article
(This article belongs to the Special Issue Machinability and Tribological Performance of Advanced Alloys)
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18 pages, 3939 KiB  
Article
An Analytical Model for Stress and Curvature Prediction of a Strip Leveling Process
by Shih-Kang Kuo, Yi-Liang Ou and Dung-An Wang
Metals 2022, 12(5), 757; https://doi.org/10.3390/met12050757 - 28 Apr 2022
Cited by 5 | Viewed by 2541
Abstract
An analytical model of a steel strip under alternate bending/reverse bending during a roller leveling process is developed. A combined isotropic/kinematic hardening model is implemented through a combined hardening parameter. A formulation of the change of the effective stress as a function of [...] Read more.
An analytical model of a steel strip under alternate bending/reverse bending during a roller leveling process is developed. A combined isotropic/kinematic hardening model is implemented through a combined hardening parameter. A formulation of the change of the effective stress as a function of the change of the effective strain under cyclic loading is combined with the developed analytical model to predict the stress distributions and residual curvature of a steel strip under roller leveling efficiently and accurately. Dissimilar to the commonly used assumption of one contact point between the stripe and the rolls, an effective radius modelling the wrap-around contact characteristics is proposed. An arc contact of the strip around a roll is described by the contact model. An oscillatory behavior of the residual curvature is observed when a range of roll intermesh setting is considered. The contact model added to the analytical model may enhance the accuracy in predicting the oscillatory behavior of the residual curvatures. A range of the roll intermesh setting can be suggested by the developed model to obtain a flat strip after roller leveling. Full article
(This article belongs to the Special Issue Machinability and Tribological Performance of Advanced Alloys)
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16 pages, 7475 KiB  
Article
Electron Backscatter Diffraction (EBSD) Analysis of Machinable Lead-Free Brass Alloys: Connecting Texture with Fracture
by Athanasios Vazdirvanidis, Andreas Rikos, Anagnostis I. Toulfatzis and George A. Pantazopoulos
Metals 2022, 12(4), 569; https://doi.org/10.3390/met12040569 - 28 Mar 2022
Cited by 8 | Viewed by 3235
Abstract
The current paper is related to the study of the microstructure and texture of two machinable lead-free brass alloys, namely CuZn42 (CW510L) and CuZn38As (CW511L), which were evaluated in the as-drawn and post heat treated condition. Electron backscatter diffraction (EBSD) was employed for [...] Read more.
The current paper is related to the study of the microstructure and texture of two machinable lead-free brass alloys, namely CuZn42 (CW510L) and CuZn38As (CW511L), which were evaluated in the as-drawn and post heat treated condition. Electron backscatter diffraction (EBSD) was employed for the examination of the brass rods’ crystallographic properties in order to correlate the effect of post processing heat treatment on the evolution of phase structure and texture towards the interpretation of dynamic (impact) fracture properties. It is shown that α- and β-phase volume fractions, mean grain size, and grain boundary misorientation are the most influential factors altering the fracture resistance of single- and dual-phase brass alloy rods. The role of grain boundary engineering, through the formation of coincidence site lattice (CSL) boundaries and their evolution during thermomechanical processing, is of major importance for the design of the mechanical behaviour of new eco-friendly machinable brass alloys. Full article
(This article belongs to the Special Issue Machinability and Tribological Performance of Advanced Alloys)
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11 pages, 5154 KiB  
Article
Multicomponent Fe-Based Bulk Metallic Glasses with Excellent Corrosion and Wear Resistances
by Guan Zhang, Wenlei Sun, Lei Xie, Chengwu Zhang, Jie Tan, Xuan Peng, Qiang Li, Xu Ma, Dongmei Zhao and Jiangtong Yu
Metals 2022, 12(4), 564; https://doi.org/10.3390/met12040564 - 27 Mar 2022
Cited by 13 | Viewed by 2521
Abstract
In this study, new multicomponent Fe54M5Cr15Mo6Si2B4P10C4 (M = Fe, Co, and Ni, denoted as Fe59, Fe54Co5, and Fe54Ni5, [...] Read more.
In this study, new multicomponent Fe54M5Cr15Mo6Si2B4P10C4 (M = Fe, Co, and Ni, denoted as Fe59, Fe54Co5, and Fe54Ni5, respectively) bulk metallic glasses (BMGs) with excellent corrosion and wear resistances were synthesized using the J-quenching technique and fluxing treatment. The synthesized Fe-based BMGs possessed a large glass-forming ability, and the maximum diameters of the Fe59, Fe54Co5, and Fe54Ni5 glassy alloy rods reached 5.5, 4.5, and 4.0 mm, respectively. The Fe59 BMG had a wide supercooled liquid region of 65 K. Potentiodynamic tests in 3.5 wt.% NaCl solution showed that the corrosion resistances of the synthesized Fe-based BMGs were relatively better than that of the 316L stainless steel. The Fe59 BMG had the highest corrosion resistance, with the lowest self-corrosion current density in the order of 10−8 A·cm−2. Wear tests showed that the synthesized Fe-based BMGs exhibited excellent wear resistances, and the wear rate of the Fe59 BMG was as low as approximately 1.73 × 10−15 m3·N−1·m−1. The rare-earth-element-free Fe-based BMGs, especially the Fe59 BMG, have a low cost, large glass-forming ability, and excellent wear and corrosion resistance, which make them good candidates for wear-and corrosion-resistant coating materials. Full article
(This article belongs to the Special Issue Machinability and Tribological Performance of Advanced Alloys)
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18 pages, 4742 KiB  
Article
Mechanical Characterization of Nanocrystalline Materials via a Finite Element Nanoindentation Model
by Konstantinos Tserpes, Panagiotis Bazios, Spiros G. Pantelakis, Maria Pappa and Nikolaos Michailidis
Metals 2021, 11(11), 1827; https://doi.org/10.3390/met11111827 - 13 Nov 2021
Cited by 2 | Viewed by 1878
Abstract
The difficulty of producing sufficient quantities of nanocrystalline materials for test specimens has led to an effort to explore alternative means for the mechanical characterization of small material volumes. In the present work, a numerical model simulating a nanoindentation test was developed using [...] Read more.
The difficulty of producing sufficient quantities of nanocrystalline materials for test specimens has led to an effort to explore alternative means for the mechanical characterization of small material volumes. In the present work, a numerical model simulating a nanoindentation test was developed using Abaqus software. In order to implement the model, the principal material properties were used. The numerical nanoindentation results were converted to stress–strain curves through an inverse algorithm in order to obtain the macroscopic mechanical properties. For the validation of the developed model, nanoindentation tests were carried out in accordance with the ISO 14577. The composition of 75% wt. tungsten and 25% wt. copper was investigated by producing two batches of specimens with a coarse-grain microstructure with an average grain size of 150 nm and a nanocrystalline microstructure with a grain diameter of 100 nm, respectively. The porosity of both batches was derived to range between 9% and 10% based on X-ray diffraction analyses. The experimental nanoidentation results in terms of load–displacement curves show a good agreement with the numerical nanoindentation results. The proposed numerical technique combined with the inverse algorithm predicts the material properties of a fully dense, nanocrystalline material with very good accuracy, but it shows an appreciable deviation with the corresponding compression results, leading to the finding that the porosity effect is a crucial parameter which needs to be taken into account in the multiscale numerical methodology. Full article
(This article belongs to the Special Issue Machinability and Tribological Performance of Advanced Alloys)
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18 pages, 5475 KiB  
Article
A Detailed Machinability Assessment of DC53 Steel for Die and Mold Industry through Wire Electric Discharge Machining
by Sarmad Ali Khan, Mudassar Rehman, Muhammad Umar Farooq, Muhammad Asad Ali, Rakhshanda Naveed, Catalin I. Pruncu and Waheed Ahmad
Metals 2021, 11(5), 816; https://doi.org/10.3390/met11050816 - 17 May 2021
Cited by 26 | Viewed by 3679
Abstract
Recently, DC53 die steel was introduced to the die and mold industry because of its excellent characteristics i.e., very good machinability and better engineering properties. DC53 demonstrates a strong capability to retain a near-net shape profile of the die, which is a very [...] Read more.
Recently, DC53 die steel was introduced to the die and mold industry because of its excellent characteristics i.e., very good machinability and better engineering properties. DC53 demonstrates a strong capability to retain a near-net shape profile of the die, which is a very challenging process with materials. To produce complex and accurate die features, the use of the wire electric discharge machining (WEDM) process takes the lead in the manufacturing industry. However, the challenge is to understand the physical science of the process to improve surface features and service properties. In this study, a detailed yet systematic evaluation of process parameters investigation is made on the influence of a wire feed, pulse on duration, open voltage, and servo voltage on the productivity (material removal rate) and material quality (surface roughness, recast layer thickness, kerf width) against the requirements of mechanical-tooling industry. Based on parametric exploration, wire feed was found the most influential parameter on kerf width: KW (45.64%), pulse on time on surface roughness: SR (84.83%), open voltage on material removal rate: MRR (49.07%) and recast layer thickness: RLT (52.06%). Also, the optimized process parameters resulted in 1.710 µm SR, 10.367 mm3/min MRR, 0.327 mm KW, and 10.443 µm RLT. Moreover, the evolution of surface features and process complexities are thoroughly discussed based on the involved physical science. The recast layer, often considered as a process limitation, was explored with the aim of minimizing the layers’ depth, as well as the recast layer and heat-affected zone. The research provides regression models based on thorough investigation to support machinists for achieving required features. Full article
(This article belongs to the Special Issue Machinability and Tribological Performance of Advanced Alloys)
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14 pages, 11325 KiB  
Article
The Process Design and Rapid Superplastic Forming of Industrial AA5083 for a Fender with a Negative Angle in a Small Batch
by Zhihao Du, Guofeng Wang and Hailun Wang
Metals 2021, 11(3), 497; https://doi.org/10.3390/met11030497 - 17 Mar 2021
Cited by 7 | Viewed by 2681
Abstract
A front automobile fender with a negative angle was trial produced via rapid superplastic forming (SPF) technology. The tensile test of industrial AA5083 was carried out at elevated temperatures, and the results showed that the maximum elongation was 242% at 480 °C/0.001 s [...] Read more.
A front automobile fender with a negative angle was trial produced via rapid superplastic forming (SPF) technology. The tensile test of industrial AA5083 was carried out at elevated temperatures, and the results showed that the maximum elongation was 242% at 480 °C/0.001 s−1. A rigid-plastic constitutive model of the SPF process was established. Initial dies of preforming and final forming were designed. The finite element method (FEM) was used to simulate the forming process and predict the thickness distribution of different areas. Furthermore, the dies were optimized to make the thickness distribution uniform. In the final structure, the maximum thinning ratio decreased from 83.2% to 63% due to the optimized design of the forming dies. The front automobile fender was then successfully fabricated by the preforming process and final forming process at 480 °C. A thickness measurement was carried out, and the minimum thickness of the preforming structure was 2.17 mm at the transverse tank, while that of the final structure was 2.49 mm near the edge of the lamp orifice. The average grain size grew from 20 to 35 μm. The grain growth led to the reduction of mechanical properties. Compared with the mechanical properties of the initial material, the maximum decrease in tensile strength for the material after superplastic forming was 5.78%, and that of elongation was 18.5%. Full article
(This article belongs to the Special Issue Machinability and Tribological Performance of Advanced Alloys)
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12 pages, 6162 KiB  
Article
Evolution of the Fretting Wear Damage of a Complex Phase Compound Layer for a Nitrided High-Carbon High-Chromium Steel
by Yong Duan, Shengguan Qu, Siyu Jia and Xiaoqiang Li
Metals 2020, 10(10), 1391; https://doi.org/10.3390/met10101391 - 19 Oct 2020
Cited by 2 | Viewed by 2323
Abstract
In this paper, the X210CrW12 steel was subjected to gas nitriding to obtain a complex phase compound layer with limited porosity. The nitrided layer was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The fretting wear behavior [...] Read more.
In this paper, the X210CrW12 steel was subjected to gas nitriding to obtain a complex phase compound layer with limited porosity. The nitrided layer was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The fretting wear behavior and the evolution of fretting wear damage of the compound layer were studied, and the worn surfaces were characterized by SEM/EDS and 3D optical profilometry. The results indicated that the compound layer showed superior fretting wear resistance and sufficient load-carrying capacity in the low loading case of 35 N, but the fracture of coarse nitrides (transformed primary carbides) was obviously detrimental to wear resistance. For the high loading case of 70 N, the low toughness of the compound layer led to the occurrence of brittle cracks, and the decrease in the thickness of the compound layer due to wear resulted in the cracking and spalling of the compound layer. Full article
(This article belongs to the Special Issue Machinability and Tribological Performance of Advanced Alloys)
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Review

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31 pages, 5533 KiB  
Review
Machinable Leaded and Eco-Friendly Brass Alloys for High Performance Manufacturing Processes: A Critical Review
by Paul Stavroulakis, Anagnostis I. Toulfatzis, George A. Pantazopoulos and Alkiviadis S. Paipetis
Metals 2022, 12(2), 246; https://doi.org/10.3390/met12020246 - 27 Jan 2022
Cited by 23 | Viewed by 6387
Abstract
The recent environmental/health and safety regulations placed restrictions of use of hazardous substances on critical manufacturing sectors and consumers’ products. Brass alloys specifically face a challenging issue concerning the elimination of lead (Pb) which has been a critical element affecting both the machinability [...] Read more.
The recent environmental/health and safety regulations placed restrictions of use of hazardous substances on critical manufacturing sectors and consumers’ products. Brass alloys specifically face a challenging issue concerning the elimination of lead (Pb) which has been a critical element affecting both the machinability and overall quality and efficiency of their manufacturing process. The adaptation of novel materials and processing routes in the green economy constitutes a crucial decision for competitive business and industry growth as a worldwide perspective with substantial industrial and social impact. This paper aims to review the emergent innovative and sustainable material solutions in the manufacturing industry, in line with environmental regulations, by highlighting smart alloy design practices and promoting new and innovative approaches for material selection and manufacturing process optimisation. In this review we analyse the processing, structure and machinability aspects of leaded brasses and underline the major guidelines and research methodologies required to overcome this technical challenge and further improve the mechanical properties and machinability of lead-free brass alloys. Various alloying and processing strategies were reviewed together with the most important failure types, as they were extracted from the existing industrial and technological experience, covering more than 20 years of research in this field. Full article
(This article belongs to the Special Issue Machinability and Tribological Performance of Advanced Alloys)
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