Editorial

3 pages, 159 KiB

Open AccessEditorial

Processing–Structure–Property Relationships in Metals

by Roberto Montanari and Alessandra Varone

Metals 2019, 9(8), 907; https://doi.org/10.3390/met9080907 - 19 Aug 2019

Cited by 3 | Viewed by 2450

The increasing demand for advanced materials in construction, transportation, communications, medicine, energy production, as well as in several other fields, is the driving force for investigating the processing–structure–property relationships [...] Full article

(This article belongs to the Special Issue Processing-Structure-Property Relationships in Metals)

Research

Jump to: Editorial, Review

20 pages, 5738 KiB

Open AccessFeature PaperArticle

Micro-Macro Relationship between Microstructure, Porosity, Mechanical Properties, and Build Mode Parameters of a Selective-Electron-Beam-Melted Ti-6Al-4V Alloy

by Giovanni Maizza, Antonio Caporale, Christian Polley and Hermann Seitz

Metals 2019, 9(7), 786; https://doi.org/10.3390/met9070786 - 15 Jul 2019

Cited by 13 | Viewed by 4490

Abstract

The performance of two selective electron beam melting operation modes, namely the manual mode and the automatic ‘build theme mode’, have been investigated for the case of a Ti-6Al-4V alloy (45–105 μm average particle size of the powder) in terms of porosity, microstructure, [...] Read more.

The performance of two selective electron beam melting operation modes, namely the manual mode and the automatic ‘build theme mode’, have been investigated for the case of a Ti-6Al-4V alloy (45–105 μm average particle size of the powder) in terms of porosity, microstructure, and mechanical properties. The two operation modes produced notable differences in terms of build quality (porosity), microstructure, and properties over the sample thickness. The number and the average size of the pores were measured using a light microscope over the entire build height. A density measurement provided a quantitative index of the global porosity throughout the builds. The selective-electron-beam-melted microstructure was mainly composed of a columnar prior β-grain structure, delineated by α-phase boundaries, oriented along the build direction. A nearly equilibrium α + β mixture structure, formed from the original β-phase, arranged inside the prior β-grains as an α-colony or α-basket weave pattern, whereas the β-phase enveloped α-lamellae. The microstructure was finer with increasing distance from the build plate regardless of the selected build mode. Optical measurements of the α-plate width showed that it varied as the distance from the build plate varied. This microstructure parameter was correlated at the sample core with the mechanical properties measured by means of a macro-instrumented indentation test, thereby confirming Hall-Petch law behavior for strength at a local scale for the various process conditions. The tensile properties, while attesting to the mechanical performance of the builds over a macro scale, also validated the indentation property measurement at the core of the samples. Thus, a direct correlation between the process parameters, microstructure, porosity, and mechanical properties was established at the micro and macro scales. The macro-instrumented indentation test has emerged as a reliable, easy, quick, and yet non-destructive alternate means to the tensile test to measure tensile-like properties of selective-electron-beam-melted specimens. Furthermore, the macro-instrumented indentation test can be used effectively in additive manufacturing for a rapid setting up of the process, that is, by controlling the microscopic scale properties of the samples, or to quantitatively determine a product quality index of the final builds, by taking advantage of its intrinsic relationship with the tensile properties. Full article

(This article belongs to the Special Issue Processing-Structure-Property Relationships in Metals)

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9 pages, 7598 KiB

Open AccessArticle

Anelastic Behavior of Small Dimensioned Aluminum

by Enrico Gianfranco Campari, Stefano Amadori, Ennio Bonetti, Raffaele Berti and Roberto Montanari

Metals 2019, 9(5), 549; https://doi.org/10.3390/met9050549 - 11 May 2019

Cited by 7 | Viewed by 2458

Abstract

In the present research, results are presented regarding the anelasticity of 99.999% pure aluminum thin films, either deposited on silica substrates or as free-standing sheets obtained by cold rolling. Mechanical Spectroscopy (MS) tests, namely measurements of dynamic modulus and damping vs. temperature, were [...] Read more.

In the present research, results are presented regarding the anelasticity of 99.999% pure aluminum thin films, either deposited on silica substrates or as free-standing sheets obtained by cold rolling. Mechanical Spectroscopy (MS) tests, namely measurements of dynamic modulus and damping vs. temperature, were performed using a vibrating reed analyzer under vacuum. The damping vs. temperature curves of deposited films exhibit two peaks which tend to merge into a single peak as the specimen thickness increases above 0.2 µm. The thermally activated anelastic relaxation processes observed on free-standing films are strongly dependent on film thickness, and below a critical value of about 20 µm two anelastic relaxation peaks can be observed; both their activation energy and relaxation strength are affected by film thickness. These results, together with those observed on bulk specimens, are indicative of specific dislocation and grain boundary dynamics, constrained by the critical values of the ratio of film thickness to grain size. Full article

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10 pages, 3081 KiB

Open AccessArticle

Effect of Rolling Speed on Microstructural and Microtextural Evolution of Nb Tubes during Caliber-Rolling Process

by Jongbeom Lee and Haguk Jeong

Metals 2019, 9(5), 500; https://doi.org/10.3390/met9050500 - 29 Apr 2019

Cited by 10 | Viewed by 2598

Abstract

This study investigated the fabrication of Nb tubes via the caliber-rolling process at various rolling speeds from 1.4 m/min to 9.9 m/min at ambient temperature, and the effect of the caliber-rolling speed on the microstructural and microtextural evolution of the Nb tubes. The [...] Read more.

This study investigated the fabrication of Nb tubes via the caliber-rolling process at various rolling speeds from 1.4 m/min to 9.9 m/min at ambient temperature, and the effect of the caliber-rolling speed on the microstructural and microtextural evolution of the Nb tubes. The caliber-rolling process affected the grain refinement when the Nb tube had a higher fraction of low angle grain boundaries. However, the grain size was identical regardless of the rolling speed. The dislocation density of the Nb tubes increased with the caliber-rolling speed according to the Orowan equation. The reduction of intensity for the <111> fiber texture and the development of the <112> fiber texture with the increase of the strain rate are considered to have decreased the internal energy by increasing the fraction of the low-energy Σ3 boundaries. Full article

(This article belongs to the Special Issue Processing-Structure-Property Relationships in Metals)

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13 pages, 3881 KiB

Open AccessArticle

Investigation of the Temperature-Related Wear Performance of Hard Nanostructured Coatings Deposited on a S600 High Speed Steel

by Eleonora Santecchia, Marcello Cabibbo, Abdel Magid Salem Hamouda, Farayi Musharavati, Anton Popelka and Stefano Spigarelli

Metals 2019, 9(3), 332; https://doi.org/10.3390/met9030332 - 15 Mar 2019

Cited by 6 | Viewed by 2815

Abstract

Thin hard coatings are widely known as key elements in many industrial fields, from equipment for metal machining to dental implants and orthopedic prosthesis. When it comes to machining and cutting tools, thin hard coatings are crucial for decreasing the coefficient of friction [...] Read more.

Thin hard coatings are widely known as key elements in many industrial fields, from equipment for metal machining to dental implants and orthopedic prosthesis. When it comes to machining and cutting tools, thin hard coatings are crucial for decreasing the coefficient of friction (COF) and for protecting tools against oxidation. The aim of this work was to evaluate the tribological performance of two commercially available thin hard coatings deposited by physical vapor deposition (PVD) on a high speed tool steel (S600) under extreme working conditions. For this purpose, pin-on-disc wear tests were carried out either at room temperature (293 K) or at high temperature (873 K) against alumina (Al₂O₃) balls. Two thin hard nitrogen-rich coatings were considered: a multilayer AlTiCrN and a superlattice (nanolayered) CrN/NbN. The surface and microstructure characterization were performed by optical profilometry, field-emission gun scanning electron microscopy (FEGSEM), and energy dispersive spectroscopy (EDS). Full article

(This article belongs to the Special Issue Processing-Structure-Property Relationships in Metals)

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14 pages, 5993 KiB

Open AccessFeature PaperArticle

Wear and Cavitation Erosion Resistance of an AlMgSc Alloy Produced by DMLS

by Marialaura Tocci, Annalisa Pola, Luca Girelli, Francesca Lollio, Lorenzo Montesano and Marcello Gelfi

Metals 2019, 9(3), 308; https://doi.org/10.3390/met9030308 - 08 Mar 2019

Cited by 26 | Viewed by 3488

Abstract

Pin-on-disk and cavitation tests were performed on an innovative Al-Mg alloy modified with Sc and Zr for additive manufacturing, which was tested in annealed condition. The damaging mechanisms were studied by observations of the morphology of the sample surface after progressive testing. These [...] Read more.

Pin-on-disk and cavitation tests were performed on an innovative Al-Mg alloy modified with Sc and Zr for additive manufacturing, which was tested in annealed condition. The damaging mechanisms were studied by observations of the morphology of the sample surface after progressive testing. These analyses allowed the identification of an adhesive wear mechanism in the first stages of pin-on-disk test, which evolved into a tribo-oxidative one due to the formation and fragmentation of an oxide layer with increasing testing distance. Regarding cavitation erosion, the AlMgSc alloy was characterized by an incubation period of approximately 1 h before mass loss was measured. Once material removal started, mass loss had a linear behavior as a function of exposure time. No preferential sites for erosion were identified, even though after some minutes of cavitation testing, the boundaries of melting pools can be seen. The comparison with literature data for AlSi10Mg alloy produced by additive manufacturing technology shows that AlMgSc alloy exhibits remarkable wear resistance, while the total mass loss after 8 h of cavitation testing is significantly higher than the value recorded for AlSi10Mg alloy in as-built condition. Full article

(This article belongs to the Special Issue Processing-Structure-Property Relationships in Metals)

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12 pages, 4098 KiB

Open AccessArticle

Metal Posts and the Effect of Material–Shape Combination on the Mechanical Behavior of Endodontically Treated Anterior Teeth

by Antonio Gloria, Saverio Maietta, Maria Richetta, Pietro Ausiello and Massimo Martorelli

Metals 2019, 9(2), 125; https://doi.org/10.3390/met9020125 - 24 Jan 2019

Cited by 7 | Viewed by 3211

Abstract

The control of the process–structure–property relationship of a material plays an important role in the design of biomedical metal devices featuring desired properties. In the field of endodontics, several post-core systems have been considered, which include a wide range of industrially developed posts. [...] Read more.

The control of the process–structure–property relationship of a material plays an important role in the design of biomedical metal devices featuring desired properties. In the field of endodontics, several post-core systems have been considered, which include a wide range of industrially developed posts. Endodontists generally use posts characterized by different materials, sizes, and shapes. Computer-aided design (CAD) and finite element (FE) analysis were taken into account to provide further insight into the effect of the material–shape combination of metal posts on the mechanical behavior of endodontically treated anterior teeth. In particular, theoretical designs of metal posts with two different shapes (conical-tapered and conical-cylindrical) and consisting of materials with Young’s moduli of 110 GPa and 200 GPa were proposed. A load of 100 N was applied on the palatal surface of the crown at 45° to the longitudinal axis of the tooth. Linear static analyses were performed with a non-failure condition. The results suggested the possibility to tailor the stress distribution along the metal posts and at the interface between the post and the surrounding structures, benefiting from an appropriate combination of a CAD-based approach and material selection. The obtained results could help to design metal posts that minimize stress concentrations. Full article

(This article belongs to the Special Issue Processing-Structure-Property Relationships in Metals)

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12 pages, 2639 KiB

Open AccessFeature PaperArticle

AA7050 Al Alloy Hot-Forging Process for Improved Fracture Toughness Properties

by Giuliano Angella, Andrea Di Schino, Riccardo Donnini, Maria Richetta, Claudio Testani and Alessandra Varone

Metals 2019, 9(1), 64; https://doi.org/10.3390/met9010064 - 11 Jan 2019

Cited by 12 | Viewed by 5254

Abstract

The conventional heat-treatment standard for the industrial post hot-forging cycle of AA7050 is regulated by the AMS4333 and AMS2770N standards. An innovative method that aimed to improve toughness behavior in Al alloys has been developed and reported. The unconventional method introduces an intermediate [...] Read more.

The conventional heat-treatment standard for the industrial post hot-forging cycle of AA7050 is regulated by the AMS4333 and AMS2770N standards. An innovative method that aimed to improve toughness behavior in Al alloys has been developed and reported. The unconventional method introduces an intermediate warm working step between the solution treating and the final ageing treatment for the high resistance aluminum alloy AA7050. The results showed several benefits starting from the grain refinement to a more stable fracture toughness KIC behavior (with an appreciable higher value) without tensile property loss. A microstructural and precipitation state characterization provided elements for the initial understanding of these improvements in the macro-properties. Full article

(This article belongs to the Special Issue Processing-Structure-Property Relationships in Metals)

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10 pages, 3839 KiB

Open AccessArticle

Effect of Al 6061 Alloy Compositions on Mechanical Properties of the Automotive Steering Knuckle Made by Novel Casting Process

by Gyu Tae Jeon, Ki Young Kim, Jung-Hwa Moon, Chul Lee, Whi-Jun Kim and Suk Jun Kim

Metals 2018, 8(10), 857; https://doi.org/10.3390/met8100857 - 20 Oct 2018

Cited by 12 | Viewed by 4713

Abstract

This study demonstrates the feasibility of a novel casting process called tailored additive casting (TAC). The TAC process involves injecting the melt several times to fabricate a single component, with a few seconds of holding between successive injections. Using TAC, we can successfully [...] Read more.

This study demonstrates the feasibility of a novel casting process called tailored additive casting (TAC). The TAC process involves injecting the melt several times to fabricate a single component, with a few seconds of holding between successive injections. Using TAC, we can successfully produce commercial-grade automotive steering knuckles with a tensile strength of 383 ± 3 MPa and an elongation percentage of 10.7 ± 1.1%, from Al 6061 alloys. To produce steering knuckles with sufficient mechanical strength, the composition of an Al 6061 alloy is optimized with the addition of Zr, Zn, and Cu as minor elements. These minor elements influence the thermal properties of the melt and alloy, such as their thermal stress, strain rate, shrinkage volume, and porosity. Optimal conditions for heat treatment before and after forging further improve the mechanical strength of the steering knuckles produced by TAC followed by forging. Full article

(This article belongs to the Special Issue Processing-Structure-Property Relationships in Metals)

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12 pages, 4520 KiB

Open AccessArticle

A Tool for Predicting the Effect of the Plunger Motion Profile on the Static Properties of Aluminium High Pressure Die Cast Components

by Elena Fiorese, Franco Bonollo and Eleonora Battaglia

Metals 2018, 8(10), 798; https://doi.org/10.3390/met8100798 - 05 Oct 2018

Cited by 9 | Viewed by 2713

Abstract

The availability of tools for predicting quality in high pressure die casting is a challenging issue since a large amount of defects is detected in components with a consequent worsening of the mechanical behavior. In this paper, a tool for predicting the effect [...] Read more.

The availability of tools for predicting quality in high pressure die casting is a challenging issue since a large amount of defects is detected in components with a consequent worsening of the mechanical behavior. In this paper, a tool for predicting the effect of the plunger motion on the properties of high pressure die cast aluminum alloys is explained and applied, by demonstrating its effectiveness. A comparison between two experiments executed through different cold chamber machines and the same geometry of the die and slightly different chemical compositions of the alloy is described. The effectiveness of the model is proved by showing the agreement between the prediction bounds and the measured data. The prediction model proposed is a general methodology independent of the machine and accounts for the effects of geometry and alloy through its coefficients. Full article

(This article belongs to the Special Issue Processing-Structure-Property Relationships in Metals)

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14 pages, 6822 KiB

Open AccessArticle

Multimodal Microstructure and Mechanical Properties of AZ91 Mg Alloy Prepared by Equal Channel Angular Pressing plus Aging

by Zhenquan Yang, Aibin Ma, Huan Liu, Jiapeng Sun, Dan Song, Ce Wang, Yuchun Yuan and Jinghua Jiang

Metals 2018, 8(10), 763; https://doi.org/10.3390/met8100763 - 26 Sep 2018

Cited by 36 | Viewed by 3906

Abstract

Developing cost-effective magnesium alloys with high strength and good ductility is a long-standing challenge for lightweight metals. Here we present a multimodal grain structured AZ91 Mg alloy with both high strength and good ductility, prepared through a combined processing route of low-pass ECAP [...] Read more.

Developing cost-effective magnesium alloys with high strength and good ductility is a long-standing challenge for lightweight metals. Here we present a multimodal grain structured AZ91 Mg alloy with both high strength and good ductility, prepared through a combined processing route of low-pass ECAP with short-time aging. This multimodal grain structure consisted of coarse grains and fine grains modified by heterogeneous precipitates, which resulted from incomplete dynamic recrystallization. This novel microstructure manifested in both superior high strength (tensile strength of 360 MPa) and good ductility (elongation of 21.2%). The high strength was mainly attributed to the synergistic effect of grain refinement, back-stress strengthening, and precipitation strengthening. The favorable ductility, meanwhile, was ascribed to the grain refinement and multimodal grain structure. We believe that our microstructure control strategy could be applicable to magnesium alloys which exhibit obvious precipitation strengthening potential. Full article

(This article belongs to the Special Issue Processing-Structure-Property Relationships in Metals)

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15 pages, 8688 KiB

Open AccessArticle

Comparative Study of Two Aging Treatments on Microstructure and Mechanical Properties of an Ultra-Fine Grained Mg-10Y-6Gd-1.5Zn-0.5Zr Alloy

by Huan Liu, He Huang, Ce Wang, Jia Ju, Jiapeng Sun, Yuna Wu, Jinghua Jiang and Aibin Ma

Metals 2018, 8(9), 658; https://doi.org/10.3390/met8090658 - 23 Aug 2018

Cited by 5 | Viewed by 3053

Abstract

Developing high strength and high ductility magnesium alloys is an important issue for weight-reduction applications. In this work, we explored the feasibility of manipulating nanosized precipitates on LPSO-contained (long period stacking ordered phase) ultra-fine grained (UFG) magnesium alloy to obtain simultaneously improved strength [...] Read more.

Developing high strength and high ductility magnesium alloys is an important issue for weight-reduction applications. In this work, we explored the feasibility of manipulating nanosized precipitates on LPSO-contained (long period stacking ordered phase) ultra-fine grained (UFG) magnesium alloy to obtain simultaneously improved strength and ductility. The effect of two aging treatments on microstructures and mechanical properties of an UFG Mg-10Y-6Gd-1.5Zn-0.5Zr alloy was systematically investigated and compared by a series of microstructure characterization techniques and tensile test. The results showed that nano γ’’ precipitates were successfully introduced in T5 peak aged alloy with no obvious increase in grain size. While T6 peak aging treatment stimulated the growth of α-Mg grains to 4.3 μm (fine grained, FG), together with the precipitation of γ’’ precipitates. Tensile tests revealed that both aging treatments remarkably improved the strengths but impaired the ductility slightly. The T5 peak aged alloy exhibited the optimum mechanical properties with ultimate strength of 431 MPa and elongation of 13.5%. This work provided a novel strategy to simultaneously improve the strength and ductility of magnesium alloys by integrating the intense precipitation strengthening with ductile LPSO-contained UFG/FG microstructure. Full article

(This article belongs to the Special Issue Processing-Structure-Property Relationships in Metals)

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17 pages, 10385 KiB

Open AccessArticle

Microstructure and Texture Inhomogeneity after Large Non-Monotonic Simple Shear Strains: Achievements of Tensile Properties

by Ebad Bagherpour, Fathallah Qods, Ramin Ebrahimi and Hiroyuki Miyamoto

Metals 2018, 8(8), 583; https://doi.org/10.3390/met8080583 - 26 Jul 2018

Cited by 8 | Viewed by 3455

Abstract

In this study, for the first time, the effect of large non-monotonic simple shear strains on the uniformity of the tensile properties of pure Cu specimens was studied and justified by means of microstructural and textural investigations. A process called simple shear extrusion, [...] Read more.

In this study, for the first time, the effect of large non-monotonic simple shear strains on the uniformity of the tensile properties of pure Cu specimens was studied and justified by means of microstructural and textural investigations. A process called simple shear extrusion, which consists of two forward and two reversed simple shear straining stages on two different slip planes, was designed in order to impose non-monotonic simple shear strains. Although the mechanism of grain refinement is continuous dynamic recrystallization, an exceptional microstructural behavior and texture were observed due to the complicated straining path results from two different slip planes and two pairs of shear directions on two different axes in a cycle of the process. The geometry of the process imposes a distribution of strain results in the inhomogeneous microstructure and texture throughout the plane perpendicular to the slip plane. Although it is expected that the yield strength in the periphery reaches that of the center by retardation, it never reaches that value, which results in the different deformation modes of the center and the periphery. The occurrence of shear reversal in each quarter of a cycle results in the elimination of some of the boundaries, an increase in the cell wall thickness, and a decrease in the Taylor factor. Change in the shear plane in each half of a cycle leads to the formation of cell boundaries in a different alignment. Since the direction of the shear and/or the shear plane change frequently in a cycle, the texture of a sample after multi-cycles of the process more closely resembles a random orientation. Full article

(This article belongs to the Special Issue Processing-Structure-Property Relationships in Metals)

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14 pages, 6514 KiB

Open AccessArticle

Effect of Rolling Reduction on Microstructure and Property of Ultrafine Grained Low-Carbon Steel Processed by Cryorolling Martensite

by Qing Yuan, Guang Xu, Sheng Liu, Man Liu, Haijiang Hu and Guangqiang Li

Metals 2018, 8(7), 518; https://doi.org/10.3390/met8070518 - 05 Jul 2018

Cited by 28 | Viewed by 3225

Abstract

A novel method of cryorolling martensite for fabricating ultrafine grained low-carbon steel with attractive strength was proposed. The results indicate that ultrafine-grain structured steel could be manufactured by cryorolling and the subsequent annealing of martensite. The mean ferrite size of 132.0 nm and [...] Read more.

A novel method of cryorolling martensite for fabricating ultrafine grained low-carbon steel with attractive strength was proposed. The results indicate that ultrafine-grain structured steel could be manufactured by cryorolling and the subsequent annealing of martensite. The mean ferrite size of 132.0 nm and the tensile strength of 978.1 MPa were obtained in a specimen with a reduction of 70% in thickness. There were peak value and valley value in the strength and grain size of ferrite with the increase of reduction from 50% to 80%, respectively. The further growth of ferrite grain at 80% reduction is attributed to the heavier distortion energy at large reduction, which activates the secondary recrystallization of ferrite. Furthermore, the distribution of ferrite grains became more uniform with increasing of reduction from 50% to 70%. Additionally, the amount of lamellar dislocation cell substructure increased with the reduction at liquid nitrogen temperature. Full article

(This article belongs to the Special Issue Processing-Structure-Property Relationships in Metals)

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11 pages, 10667 KiB

Open AccessArticle

Effects of Tempering on the Microstructure and Properties of a High-Strength Bainite Rail Steel with Good Toughness

by Min Zhu, Guang Xu, Mingxing Zhou, Qing Yuan, Junyu Tian and Haijiang Hu

Metals 2018, 8(7), 484; https://doi.org/10.3390/met8070484 - 25 Jun 2018

Cited by 27 | Viewed by 4189

Abstract

An advanced bainite rail with high strength–toughness combination was produced in a steel mill and the effects of tempering on the microstructure and properties of the bainite rail steel were investigated by optical microscopy, transmission electron microscopy, electron back-scattering diffraction and X-ray diffraction. [...] Read more.

An advanced bainite rail with high strength–toughness combination was produced in a steel mill and the effects of tempering on the microstructure and properties of the bainite rail steel were investigated by optical microscopy, transmission electron microscopy, electron back-scattering diffraction and X-ray diffraction. Results indicate that the tensile strength, elongation and impact toughness were about 1470 MPa, 14.5% and 83 J/cm², respectively, after tempering at 400 °C for 200 min. Therefore, a high-strength bainite rail steel with good toughness was developed. In addition, the amount of retained austenite (RA) decreased due to bainite transformation after low-temperature tempering (300 °C) and RA almost disappeared after high-temperature tempering (500 °C). Moreover, as the tempering temperature increased, the tensile strength of the rail head first decreased due to the decreased dislocation density and carbon content in bainite ferrite and the coarseness of bainite ferrite, and then increased because of carbide precipitation at high-temperature tempering. Furthermore, RA played a significant role in the toughness of bainite rail. The elongation and toughness of the rail obviously decreased after tempering at 500 °C for 200 min because of the disappearance of RA and appearance of carbides. Full article

(This article belongs to the Special Issue Processing-Structure-Property Relationships in Metals)

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16 pages, 5782 KiB

Open AccessArticle

Microstructural and XRD Analysis and Study of the Properties of the System Ti-TiAl-B₄C Processed under Different Operational Conditions

by Isabel Montealegre-Meléndez, Cristina Arévalo, Eva M. Pérez-Soriano, Michael Kitzmantel and Erich Neubauer

Metals 2018, 8(5), 367; https://doi.org/10.3390/met8050367 - 21 May 2018

Cited by 15 | Viewed by 6791

Abstract

High specific modulus materials are considered excellent for the aerospace industry. The system Ti-TiAl-B₄C is presented herein as an alternative material. Secondary phases formed in situ during fabrication vary depending on the processing conditions and composition of the starting materials. The [...] Read more.

High specific modulus materials are considered excellent for the aerospace industry. The system Ti-TiAl-B₄C is presented herein as an alternative material. Secondary phases formed in situ during fabrication vary depending on the processing conditions and composition of the starting materials. The final behaviors of these materials are therefore difficult to predict. This research focuses on the study of the system Ti-TiAl-B₄C, whereby relations between microstructure and properties can be predicted in terms of the processing parameters of the titanium matrix composites (TMCs). The powder metallurgy technique employed to fabricate the TMCs was that of inductive hot pressing (iHP) since it offers versatility and flexibility. The short processing time employed (5 min) was set in order to test the temperature as a major factor of influence in the secondary reactions. The pressure was also varied. In order to perform this research, not only were X-Ray Diffraction (XRD) analyses performed, but also microstructural characterization through Scanning Electron Microscopy (SEM). Significant results showed that there was an inflection temperature from which the trend to form secondary compounds depended on the starting material used. Hence, the addition of TiAl as an elementary blend or as prealloyed powder played a significant role in the final behavior of the TMCs fabricated, where the prealloyed TiAl provides a better precursor of the formation of the reinforcement phases from 1100 °C regardless of the pressure. Full article

(This article belongs to the Special Issue Processing-Structure-Property Relationships in Metals)

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Review

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26 pages, 6248 KiB

Open AccessFeature PaperReview

Alloys for Aeronautic Applications: State of the Art and Perspectives

by Antonio Gloria, Roberto Montanari, Maria Richetta and Alessandra Varone

Metals 2019, 9(6), 662; https://doi.org/10.3390/met9060662 - 06 Jun 2019

Cited by 128 | Viewed by 19261

Abstract

In recent years, a great effort has been devoted to developing a new generation of materials for aeronautic applications. The driving force behind this effort is the reduction of costs, by extending the service life of aircraft parts (structural and engine components) and [...] Read more.

In recent years, a great effort has been devoted to developing a new generation of materials for aeronautic applications. The driving force behind this effort is the reduction of costs, by extending the service life of aircraft parts (structural and engine components) and increasing fuel efficiency, load capacity and flight range. The present paper examines the most important classes of metallic materials including Al alloys, Ti alloys, Mg alloys, steels, Ni superalloys and metal matrix composites (MMC), with the scope to provide an overview of recent advancements and to highlight current problems and perspectives related to metals for aeronautics. Full article

(This article belongs to the Special Issue Processing-Structure-Property Relationships in Metals)

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