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16 pages, 13197 KiB

Open AccessArticle

Roles of Al and Mg on the Microstructure and Corrosion Resistance of Zn-Al-Mg Hot-Dipped Coated Steel

by Taixiong Guo, Yuhao Wang, Liusi Yu, Yongqing Jin, Bitao Zeng, Baojie Dou, Xiaoling Liu and Xiuzhou Lin

Materials 2024, 17(7), 1512; https://doi.org/10.3390/ma17071512 - 27 Mar 2024

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Abstract

In this work, a novel zinc–aluminum–magnesium (Zn-Al-Mg, ZM) coated steel was prepared using the hot-dip method. The microstructure and corrosion resistance of the ZM-coated steel were investigated. Compared to the conventional galvanized steel (GI), the ZM coating demonstrated a distinctive phase structure, consisting [...] Read more.

In this work, a novel zinc–aluminum–magnesium (Zn-Al-Mg, ZM) coated steel was prepared using the hot-dip method. The microstructure and corrosion resistance of the ZM-coated steel were investigated. Compared to the conventional galvanized steel (GI), the ZM coating demonstrated a distinctive phase structure, consisting of Zn phase, binary eutectic (Zn/MgZn₂), and ternary eutectic (Zn/Al/MgZn₂). The corrosion resistance of the ZM-coated and GI-coated steels was evaluated by neutral salt spray test (NSST), polarization and electrochemical impedance spectroscopy (EIS). The results indicated that ZM-coated steel provided superior long-term corrosion protection in a NaCl environment compared to GI-coated steel. The scanning vibrating electrode technique (SVET) proved to be an effective method for investigating the evolution of the anodic and cathodic on the local coating surface. GI-coated steel exhibited a potential and current density distribution between the cathodic and anodic sites nearly three orders of magnitude higher than that of ZM-coated steel, suggesting a higher corrosion rate for GI-coated steel. Full article

(This article belongs to the Special Issue Research on Heat Treatment of Advanced Metallic Materials (2nd Volume))

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16 pages, 25458 KiB

Open AccessArticle

Research on the Hot Deformation Process of A100 Steel Based on High-Temperature Rheological Behavior and Microstructure

by Chaoyuan Sun, Yi Qin, Yang Liu, Guiqian Xiao, Jiansheng Zhang and Jie Zhou

Materials 2024, 17(5), 991; https://doi.org/10.3390/ma17050991 - 21 Feb 2024

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Abstract

To obtain the optimal hot deformation process, the rheological and dynamic recrystallization behaviors of A100 steel were researched through isothermal compression tests. Firstly, a Hensel-Spittel constitutive model was established based on the stress–strain curves. Secondly, dynamic recrystallization percentage and grain size models were [...] Read more.

To obtain the optimal hot deformation process, the rheological and dynamic recrystallization behaviors of A100 steel were researched through isothermal compression tests. Firstly, a Hensel-Spittel constitutive model was established based on the stress–strain curves. Secondly, dynamic recrystallization percentage and grain size models were established to identify the necessary conditions for complete dynamic recrystallization. Finally, microstructural analysis was employed to validate the accuracy of the recrystallization model. The results indicate that the flow stress is highly sensitive to both the strain rate and the temperature, and the HS model demonstrates a high predictive accuracy, with a correlation coefficient of 0.9914. There exists a contradictory relationship between decreasing the average grain size and increasing the recrystallization percentage. The higher the percentage of dynamic recrystallization, the larger the average grain size tends to be. This situation should be avoided when devising the actual processing procedures. The optimal hot working processes for achieving complete dynamic recrystallization and a smaller average grain size are as follows: a strain equal to or greater than 0.6, a temperature between 1193 and 1353 K, and a strain rate between 0.1 and 1 s⁻¹. Full article

(This article belongs to the Special Issue Research on Heat Treatment of Advanced Metallic Materials (2nd Volume))

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14 pages, 4854 KiB

Open AccessArticle

Effects of Heat Treatment on Microstructures and Mechanical Properties of a Low-Alloy Cylinder Liner

by Wenjuan Zhang, Hao Gao, Dong Liu, Ying Gao, Yuqing Zhang and Lingchao Kong

Materials 2024, 17(4), 802; https://doi.org/10.3390/ma17040802 - 07 Feb 2024

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Abstract

Cylinder liners, considered a crucial component of internal combustion (IC) engines, often require excellent mechanical properties to ensure optimal engine performance under elevated temperatures, pressures, and varying loads. In this work, a new low-alloy cylinder liner, incorporating a low content of molybdenum, copper, [...] Read more.

Cylinder liners, considered a crucial component of internal combustion (IC) engines, often require excellent mechanical properties to ensure optimal engine performance under elevated temperatures, pressures, and varying loads. In this work, a new low-alloy cylinder liner, incorporating a low content of molybdenum, copper, and chromium into gray cast iron, was fabricated using a centrifugal casting process. Subsequently, the heat treatment processes were designed to achieve bainite microstructures in the cylinder liner through rapid air cooling, isothermal transformation, and tempering. The effects of different air-cooling rates and tempering temperatures on the microstructure evolution and mechanical properties of cylinder liner were investigated. The results revealed that during the supercooled austenite transformation process, rapid air cooling at a rate of 14.5–23.3 °C/s can effectively bypass the formation of pearlitic structures and directly induce the formation of bainite structures. Once the temperature exceeded 480–520 °C, hardness and tensile strength increased with the temperature increase owing to the enhancement of the lower bainite content, the reduction of residual austenite, and the precipitation of the fine hard carbides in the matrix. With temperatures above 520–550 °C, the carbide and lower bainite organization coarsened, thereby reducing the hardness and tensile strength of the material. Therefore, the optimal heat treatment parameters were rapid cooling at 14.5–23.3 °C/s rate to obtain bainite, and tempering of 480–520 °C for finer and more uniform bainite. In addition, the results of the characterization of the mechanical properties of the cylinder liner after heat treatment showed that the hardness, tensile strength, and wear resistance were improved with the refinement of the bainite. Full article

(This article belongs to the Special Issue Research on Heat Treatment of Advanced Metallic Materials (2nd Volume))

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13 pages, 8361 KiB

Open AccessArticle

Study on Porosity of Thermal-Sprayed Commercially Pure Aluminum Coating

by Bo Li, Lei Fan, Jie Bai, Jinhang He, Jianfeng Su, Song Wang, Chao Deng, Shifeng Liu and Zhiqing Zhang

Materials 2023, 16(19), 6612; https://doi.org/10.3390/ma16196612 - 09 Oct 2023

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Abstract

Porosity is closely related to the corrosion and wear properties of a coating processed by thermal-spraying technology, and the quantitative characterization of porosity is a crucial part of the research on coating structures. The current image analysis method often uses the mechanical polishing [...] Read more.

Porosity is closely related to the corrosion and wear properties of a coating processed by thermal-spraying technology, and the quantitative characterization of porosity is a crucial part of the research on coating structures. The current image analysis method often uses the mechanical polishing method recommended by ISO to measure a coating porosity. This method has been proved to be an effective method for the characterization of oxide coatings. However, due to the significant differences in the physical and chemical properties between aluminum and oxides, this method may not be suitable for aluminum coatings, and a more appropriate approach needs to be explored. In this paper, the effects of three polishing technologies (mechanical polishing, argon-ion-beam polishing, and electrolytic polishing) on the porosity measurement of pure aluminum coatings were compared and studied. The research results showed that the commonly used mechanical polishing method and more advanced argon-ion-beam polishing method could not completely reveal the pore structure because SiC particles would be embedded in the pure aluminum coatings during mechanical polishing, filling large pores. Although electrolytic polishing technology had advantages in revealing the macroporous structure, it would introduce a microporous structure and oxides, which would affect the measurement of the coating porosity. The composite polishing technology (electrolytic polishing + argon-ion-beam polishing) could perfectly reveal the pore structure in the pure-aluminum coating, and the porosity of arc-sprayed aluminum coating was 9.9%, which was close to the macroscopic true value measured using the weighing method of 10.2%. Full article

(This article belongs to the Special Issue Research on Heat Treatment of Advanced Metallic Materials (2nd Volume))

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15 pages, 12176 KiB

Open AccessArticle

Dynamic Spheroidization Mechanism and Its Orientation Dependence of Ti-6Al-2Mo-2V-1Fe Alloy during Subtransus Hot Deformation

by Jinyang Ge, Xiaodong Zhan, Chao Li, Xiaoyong Zhang and Kechao Zhou

Materials 2023, 16(17), 5752; https://doi.org/10.3390/ma16175752 - 22 Aug 2023

Cited by 1 | Viewed by 564

Abstract

The dynamic spheroidization mechanism and its orientation dependence in Ti-6Al-2Mo-2V-1Fe alloys during subtransus hot deformation were studied in this work. For this purpose, hot compression tests were carried out at temperatures of 780–880 °C, with strain rates of 0.001–0.1 s⁻¹. Based [...] Read more.

The dynamic spheroidization mechanism and its orientation dependence in Ti-6Al-2Mo-2V-1Fe alloys during subtransus hot deformation were studied in this work. For this purpose, hot compression tests were carried out at temperatures of 780–880 °C, with strain rates of 0.001–0.1 s⁻¹. Based on SEM, EBSD and TEM characterization, the results showed that the aspect ratio of the α phase decreased with increasing deformation temperatures and decreasing strain rates. At 880 °C/0.001 s⁻¹, the aspect ratio of the α phase was the smallest at 2.05. The proportion of HAGBs decreased with increasing temperatures and strain rates, which was different from the trend of the spheroidization; this indicated that the formation of HAGBs was not necessary for the spheroidization process. Furthermore, the formation of the α/α interface was related to the evolution of dislocations and twin boundaries at high (880 °C) and low temperatures (780 °C), respectively. Moreover, the dependence of lamellar spheroidization on the crystallographic orientation tilt from the compression direction (θ) was clarified: when θ was between 45° and 60°, both the prism <a> slip and basal <a> slip systems were activated together, which was more favorable for spheroidization. This study could provide guidance for titanium alloy process designs and microstructure regulation. Full article

(This article belongs to the Special Issue Research on Heat Treatment of Advanced Metallic Materials (2nd Volume))

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16 pages, 7924 KiB

Open AccessArticle

Improvement in Mechanical Properties of Al2024 Alloy Using Mechanical Working and Heat Treatment

by Zhengfeng Zhu, Renbao Qin, Yishan Sun, Jie Tang, Fulin Jiang and Chuang You

Materials 2023, 16(16), 5568; https://doi.org/10.3390/ma16165568 - 10 Aug 2023

Cited by 1 | Viewed by 843

Abstract

Extrusion speed has a significant influence on the extrusion temperature, microstructure and mechanical properties of the material in the repetitive continuous extrusion forming (RCEF) process. In this work, the mechanical properties of Al2024 were improved by adjusting the speed (with a general range [...] Read more.

Extrusion speed has a significant influence on the extrusion temperature, microstructure and mechanical properties of the material in the repetitive continuous extrusion forming (RCEF) process. In this work, the mechanical properties of Al2024 were improved by adjusting the speed (with a general range of 2–10 rpm) of repetitive continuous extrusion and applying subsequent heat treatment. During the RCEF process, an increase in the extrusion speed from 4 to 8 rpm was found to increase the extrusion temperature and then enhance the solid solution function. The grain size was affected by the combined effect of deformation speed and its induced temperature. A high-strength Al2024 (ultimate tensile strength of 497.6 MPa) with good elongation (12.93%) was obtained by increasing the extrusion speed and conducting solid solution and artificial aging treatments. The main strengthening mechanisms could be attributed to finer grain size and a larger amount of S (Al₂CuMg) precipitates. Full article

(This article belongs to the Special Issue Research on Heat Treatment of Advanced Metallic Materials (2nd Volume))

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14 pages, 2821 KiB

Open AccessArticle

Theoretical Strategy for Interface Design and Thermal Performance Prediction in Diamond/Aluminum Composite Based on Scattering-Mediated Acoustic Mismatch Model

by Zhiliang Hua, Kang Wang, Wenfang Li and Zhiyan Chen

Materials 2023, 16(12), 4208; https://doi.org/10.3390/ma16124208 - 06 Jun 2023

Cited by 1 | Viewed by 766

Abstract

Inserting modification layers at the diamond/Al interface is an effective technique in improving the interfacial thermal conductance (ITC) of the composite. However, few study reports the effect of interfacial structure on the thermal conductivity (TC) of diamond/Al composites at room temperature. Herein, the [...] Read more.

Inserting modification layers at the diamond/Al interface is an effective technique in improving the interfacial thermal conductance (ITC) of the composite. However, few study reports the effect of interfacial structure on the thermal conductivity (TC) of diamond/Al composites at room temperature. Herein, the scattering-mediated acoustic mismatch model, suitable for evaluating the ITC at room temperature, is utilized to predict the TC performance of the diamond/Al composite. According to the practical microstructure of the composites, the reaction products at diamond/Al interface on the TC performance are concerned. Results indicate that the TC of the diamond/Al composite is dominantly affected by the thickness, the Debye temperature and the TC of the interfacial phase, meeting with multiple documented results. This work provides a method to assess the interfacial structure on the TC performance of metal matrix composite at room temperature. Full article

(This article belongs to the Special Issue Research on Heat Treatment of Advanced Metallic Materials (2nd Volume))

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Review

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18 pages, 4335 KiB

Open AccessReview

Development and Prospect of Vacuum High-Pressure Gas Quenching Technology

by Shengde Hu, Lin Zhu, Mao Zhang, Xuefeng Tang and Xinyun Wang

Materials 2023, 16(23), 7413; https://doi.org/10.3390/ma16237413 - 29 Nov 2023

Viewed by 866

Abstract

As industrial modernization surges forward, the heat treatment industry strives for lower pollution, reduced oxidation and defects, minimized waste, and automatization. This paper reviews the mechanisms, processes, equipment, and simulations of the vacuum gas quenching technology, presenting a comprehensive account of the structure [...] Read more.

As industrial modernization surges forward, the heat treatment industry strives for lower pollution, reduced oxidation and defects, minimized waste, and automatization. This paper reviews the mechanisms, processes, equipment, and simulations of the vacuum gas quenching technology, presenting a comprehensive account of the structure and working principle of a typical vacuum gas quenching furnace. Firstly, the mechanism of the heat transfer process, flow process, and flow–heat transfer–phase transition coupling were summarized. Then, the influences of process parameters on the mechanical properties and distortion of vacuum gas quenched workpieces, as well as the process optimization methods, were discussed. Finally, the advantages of vacuum gas quenching in energy saving, low pollution, and high efficiency were introduced, with the future development directions figured out. Full article

(This article belongs to the Special Issue Research on Heat Treatment of Advanced Metallic Materials (2nd Volume))

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35 pages, 10639 KiB

Open AccessEditor’s ChoiceReview

A Review on Controlling Grain Boundary Character Distribution during Twinning-Related Grain Boundary Engineering of Face-Centered Cubic Materials

by Yu-Qing Zhang, Guo-Zheng Quan, Jiang Zhao, Yan-Ze Yu and Wei Xiong

Materials 2023, 16(13), 4562; https://doi.org/10.3390/ma16134562 - 24 Jun 2023

Cited by 1 | Viewed by 1740

Abstract

Grain boundary engineering (GBE) is considered to be an attractive approach to microstructure control, which significantly enhances the grain-boundary-related properties of face-centered cubic (FCC) metals. During the twinning-related GBE, the microstructures are characterized as abundant special twin boundaries that sufficiently disrupt the connectivity [...] Read more.

Grain boundary engineering (GBE) is considered to be an attractive approach to microstructure control, which significantly enhances the grain-boundary-related properties of face-centered cubic (FCC) metals. During the twinning-related GBE, the microstructures are characterized as abundant special twin boundaries that sufficiently disrupt the connectivity of the random boundary network. However, controlling the grain boundary character distribution (GBCD) is an extremely difficult issue, as it strongly depends on diverse processing parameters. This article provides a comprehensive review of controlling GBCD during the twinning-related GBE of FCC materials. To commence, this review elaborates on the theory of twinning-related GBE, the microscopic mechanisms used in the optimization of GBCD, and the optimization objectives of GBCD. Aiming to achieve control over the GBCD, the influence of the initial microstructure, thermo-mechanical processing (TMP) routes, and thermal deformation parameters on the twinning-related microstructures and associated evolution mechanisms are discussed thoroughly. Especially, the development of twinning-related kinetics models for predicting the evolution of twin density is highlighted. Furthermore, this review addresses the applications of twinning-related GBE in enhancing the mechanical properties and corrosion resistance of FCC materials. Finally, future prospects in terms of controlling the GBCD during twinning-related GBE are proposed. This study will contribute to optimizing the GBCD and designing GBE routes for better grain-boundary-related properties in terms of FCC materials. Full article

(This article belongs to the Special Issue Research on Heat Treatment of Advanced Metallic Materials (2nd Volume))

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