Microstructure and Mechanical Property Relationships in Metallic Materials

A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Metal Casting, Forming and Heat Treatment".

Deadline for manuscript submissions: closed (31 March 2024) | Viewed by 9644

Special Issue Editor


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Guest Editor
Department of Mechanical, Automotive and Materials Engineering, University of Windsor, Windsor, ON N9A, Canada
Interests: tribology and wear; mechanical properties of lightweight alloys for automotive and aerospace applications; titanium and aluminum alloys; electrical steel; microstructural evolution in additive manufacturing

Special Issue Information

Dear Colleagues,

The properties of metallic materials are influenced by their microstructures. The microstructure of metallic materials is described by grain size, types of phases present, and description of their structure, shape, and size distributions. The shape and size of grains and the orientation of the crystal planes within the grains (texture) are determined by processing parameters. In addition, crystalline defects such as grain boundaries, heterophase interfaces, dislocations and point defects are important microstructural features that often control the properties of metals. The relation between fabrication and processing, microstructure and mechanical properties has been a topic of many studies. Clarification of the causes behind metal behavior under varying conditions and predicting the behavior of materials with certain structures can only be achieved through more in-depth knowledge of the metallic materials.

This Special Issue will include novel studies pertaining to the influences of processing technologies on the microstructural evolution; topics include but are not limited to conventional and new forms of fabrication techniques such as additive manufacturing and development of novel microstructures by means of thermomechanical treatments for required properties, as well as the analytical methods employed in elucidating the mechanical properties of metallic materials. Novel experimental and theoretical studies of the structure of the metallic material will also be considered.

Prof. Dr. Afsaneh Edrisy
Guest Editor

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Keywords

  • Microstructure
  • Nano and atomic structures
  • Texture
  • Mechanical properties
  • Microstructural evolution
  • Thermomechanical treatment
  • Materials processing
  • Additive manufacturing

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Published Papers (4 papers)

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Research

17 pages, 8953 KiB  
Article
Mechanical Characterization at Nanoscale of Austenite, Ferrite, and Sigma Phases via Hardness Measurement and Fretting Wear Behavior of a Duplex Stainless Steel
by Jomar José Knaip Ribeiro, Alba Regina Turin, Yamid E. Nuñez de la Rosa, Pedro Victorio Caetano Abrantes Quadros, Oriana Palma Calabokis, Carlos Maurício Lepienski, Silvio Francisco Brunatto and Paulo César Borges
Metals 2023, 13(5), 864; https://doi.org/10.3390/met13050864 - 29 Apr 2023
Cited by 2 | Viewed by 2331
Abstract
This study aimed at the mechanical characterization, on a nanometric scale, of the constituents obtained for different fractions in duplex stainless-steel plates subjected to 850, 950, 1000, and 1150 °C heating treatments via hardness measurements and determining their influences on the fretting wear [...] Read more.
This study aimed at the mechanical characterization, on a nanometric scale, of the constituents obtained for different fractions in duplex stainless-steel plates subjected to 850, 950, 1000, and 1150 °C heating treatments via hardness measurements and determining their influences on the fretting wear behavior of the studied steel. The obtained ferrite (α)-, austenite (γ)-, and sigma (σ)-phase fractions were determined using optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques. The mechanical characterization was carried out using hardness measurement and fretting wear techniques via nanoindentation. For comparison purposes, the Vickers microhardness was also characterized to determine the effect of the σ phase, which eventually formed, on the obtained microstructure properties as a whole. Two distinct behaviors were observed, depending on the eventual formation of σ phase as a function of the treatment temperature: (i) specimens treated at 850 and 950 °C showed a hardening effect (HV0.5 values of 333 ± 15 and 264 ± 13, respectively) due to σ-phase precipitation (hereafter termed ‘as-aged’), and (ii) specimens treated at 1000 and 1150 °C (with HV0.5 values of 240 ± 13 and 249 ± 4, respectively) showed no σ-phase precipitation (hereafter termed ‘as-solubilized’). The increases in the microhardness values for the as-aged specimens were attributed to the hardness of the σ-phase precipitates (which showed nanohardness values varying in the 8.0–8.5 GPa range), which was approximately twice that of the austenite and ferrite grains (both phases showed nanohardness values in the 3.6–4.1 GPa range, on average). When formed (for fractions on the order of 8% and 3% at 850 and 950 °C, respectively), σ phase was mainly observed at the α/γ grain interfaces or boundaries. Fretting wear tests, using a diamond sphere with a radius of 10 μm as the counter body and a load of 20 mN, revealed the same wear mechanisms in the α/γ matrix for all studied conditions. However, as-solubilized specimens (heat-treated at 1000 and 1150 °C) displayed higher resistance to fretting micro-wear in the austenitic grains compared to the ferritic grains, indicating lower plastic deformation in the respective wear scars on the obtained tracks. In particular, as-aged specimens (heat-treated at 850 and 950 °C) exhibited lower coefficients of friction due to their higher surface resistances. The localized wear at σ-phase grains was much less pronounced than at ferrite and austenite grains. Overall, this study provides valuable insights into the mechanical behavior of microstructural changes in duplex steel at the nanometric scale. Full article
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12 pages, 25210 KiB  
Article
Effect of Coiling Temperature on Microstructure and Properties of Titanium Strengthened Weathering Building Steel
by Zhengrong Li, Zhenhu Lv, Chuangwei Wang, Lei Liu, Kaiyu Cui and Zhengzhi Zhao
Metals 2023, 13(4), 804; https://doi.org/10.3390/met13040804 - 19 Apr 2023
Cited by 2 | Viewed by 1446
Abstract
For weathering steel used in building, it is necessary not only to ensure weather resistance, but also to improve the strength and yield ratio. This study investigates the strengthening effect of Ti microalloying on the tested steel by conducting continuous cooling transformation tests [...] Read more.
For weathering steel used in building, it is necessary not only to ensure weather resistance, but also to improve the strength and yield ratio. This study investigates the strengthening effect of Ti microalloying on the tested steel by conducting continuous cooling transformation tests of undercooled austenite and comparative tests of microstructure and performance at different coiling temperatures, with 0.07 wt.% Ti added to the weathering building test steel. The results show that, with an increase in cooling rate (0.1~50 °C/s), the room temperature microstructure of different cooling rates gradually transitions as follows: F + P, F + P + B, F + B and B + M; in addition, the hardness increases. Polygonal ferrite and pearlite were obtained by coiling at 650 °C; quasi-polygonal ferrite, acicular ferrite, pearlite and a small amount of bainite were obtained by coiling at 600 °C; and bainite was obtained by coiling at 550 °C. With a decrease in coiling temperature, the strength of the test steel increased, the yield ratio increased, the elongation after fracture decreased and the elongation at the yield point decreased. Compared with those observed at 650 °C, the nano precipitation phases observed in the sample at 600 °C were smaller in size, higher in number and higher in dislocation density. The combined action of second-phase precipitation strengthening and dislocation strengthening increased the strength and yield ratio of the test steel. This study will be helpful in guiding the improvement of strength grades for weathering steel used in building and industrial production. Full article
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13 pages, 4823 KiB  
Article
Effect of Quenching and Partitioning Heat Treatment on the Fatigue Behavior of 42SiCr Steel
by Marco Thomä and Guntram Wagner
Metals 2021, 11(11), 1699; https://doi.org/10.3390/met11111699 - 25 Oct 2021
Cited by 5 | Viewed by 1859
Abstract
The manufacturing of advanced high-strength steels with enhanced ductility is a persistent aim of research. The ability of a material to absorb high loads while showing a high deformation behavior is a major task for many industrial fields like the mobility sector. Therefore, [...] Read more.
The manufacturing of advanced high-strength steels with enhanced ductility is a persistent aim of research. The ability of a material to absorb high loads while showing a high deformation behavior is a major task for many industrial fields like the mobility sector. Therefore, the material properties of advanced high-strength steels are one of the most important impact factors on the resulting cyclic fatigue behavior. To adjust advanced material properties, resulting in high tensile strengths as well as an enhanced ductility, the heat treatment process of quenching and partitioning (QP) was developed. The quenching takes place in a field between martensite start and martensite finish temperature and the subsequent partitioning is executed at slightly elevated temperatures. Regarding the sparsely investigated field of fatigue research on quenched and partitioned steels, the present work investigates the influence of a QP heat treatment on the resulting microstructure by light and scanning electron microscopy as well as on the mechanical properties such as tensile strength and resistance against fatigue regarding two different heat treatment conditions (QP1, QP2) in comparison to the cold-rolled base material of 42SiCr steel. Therefore, the microscopic analysis proved the presence of a characteristic quenched and partitioned microstructure consisting of a martensitic matrix and partial areas of retained austenite, whereas carbides were also present. Differences in the amount of retained austenite could be observed by using X-ray diffraction (XRD) for the different QP routes, which influence the mechanical properties resulting in higher tensile strength of about 2000 MPa for QP1 compared to about 1600 MPa for QP2. Furthermore, the transition for the fatigue limit was approximated by using stepwise load increase tests (LIT) and afterwards verified by constant amplitude tests (CAT) in accordance with the staircase method, whereas the QP1 condition reached the highest fatigue strength of 900 MPa. Subsequent light and scanning electron microscopy of selected fractured surfaces and runouts showed a different behavior regarding the size of the fatigue fracture area and also differences in the microstructure of these runouts. Full article
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19 pages, 23233 KiB  
Article
Fatigue Improvement of Additive Manufactured Ti–TiB Material through Shot Peening
by Liza-Anastasia DiCecco, Mehdi Mehdi and Afsaneh Edrisy
Metals 2021, 11(9), 1423; https://doi.org/10.3390/met11091423 - 9 Sep 2021
Cited by 6 | Viewed by 2814
Abstract
In this work, fatigue improvement through shot peening of an additive manufactured Ti–TiB block produced through Plasma Transferred Arc Solid Free-Form Fabrication (PTA-SFFF) was investigated. The microstructure and composition were explored through analytical microscopy techniques such as scanning and transmission electron microscopy (SEM, [...] Read more.
In this work, fatigue improvement through shot peening of an additive manufactured Ti–TiB block produced through Plasma Transferred Arc Solid Free-Form Fabrication (PTA-SFFF) was investigated. The microstructure and composition were explored through analytical microscopy techniques such as scanning and transmission electron microscopy (SEM, TEM) and electron backscatter diffraction (EBSD). To investigate the isotropic behavior within the additive manufactured Ti–TiB blocks, tensile tests were conducted in longitudinal, diagonal, and lateral directions. A consistent tensile behavior was observed for all the directions, highlighting a nearly isotropic behavior within samples. Shot peening was introduced as a postmanufacturing treatment to enhance the mechanical properties of AM specimens. Shot peening led to a localized increase in hardness at the near-surface where stress-induced twins are noted within the affected microstructure. The RBF-200 HT rotating-beam fatigue machine was utilized to conduct fatigue testing on untreated and shot-peened samples, starting at approximately 1/2 the ultimate tensile strength of the bulk material and testing within low- (<105 cycles) to high-cycle (>105 cycles) regimes. Shot-peened samples experienced significant improvement in fatigue life, increasing the fitted endurance limit from 247.8 MPa for the untreated samples to 318.3 MPa, leading to an increase in fatigue resistance of approximately 28%. Full article
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