Metals

16 pages, 7318 KiB

Open AccessArticle

Evaluation of Microstructural and Mechanical Behavior of AHSS CP780 Steel Welded by GMAW-Pulsed and GMAW-Pulsed-Brazing Processes

by Alan Jadir Romero-Orozco, José Jaime Taha-Tijerina, Rene De Luna-Alanís, Victor Hugo López-Morelos, María del Carmen Ramírez-López, Melchor Salazar-Martínez and Francisco Fernando Curiel-López

Metals 2022, 12(3), 530; https://doi.org/10.3390/met12030530 - 21 Mar 2022

Cited by 5 | Viewed by 2697

Abstract

Joints of complex phase 780 (CP-780) advanced high strength steel (AHSS) were carried out by using an ER-CuAl-A2 filler metal for the gas metal arc welding pulsed brazing (GMAW-P- brazing) process and the ER-80S-D2 for the GMAW-P process employing two levels of heat [...] Read more.

Joints of complex phase 780 (CP-780) advanced high strength steel (AHSS) were carried out by using an ER-CuAl-A2 filler metal for the gas metal arc welding pulsed brazing (GMAW-P- brazing) process and the ER-80S-D2 for the GMAW-P process employing two levels of heat input. The phases in the weld bead and HAZ were analyzed, and the evaporation of zinc by means of scanning electron microscopy (SEM) was also monitored. The mechanical properties of the welded joints were evaluated by tension, microhardness and vertical impact tests. It was found that there was greater surface Zn evaporation in the joints welded with the GMAW-P process as compared to the GMAW-P-brazing process. The best results in tensile strength were observed in the joints welded with GMAW-P-brazing process, which increased by ~68% with respect to those of the GMAW-P. This behavior can be attributed to the formation of an intermetallic complex compound Cu-Al-Fe in the fusion line. Full article

(This article belongs to the Special Issue Mechanical Properties Assessment of Alloys during Welding Process)

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13 pages, 1909 KiB

Open AccessArticle

Effect of Milling Parameters on Mechanical Properties and In Vitro Biocompatibility of Mg-Zn-Co Ternary Alloy

by Sehrish Mukhtar, Muhammad Kamran, Rafiq Ahmed and Asima Tayyeb

Metals 2022, 12(3), 529; https://doi.org/10.3390/met12030529 - 21 Mar 2022

Cited by 3 | Viewed by 2293

Abstract

Magnesium (Mg) is a potential candidate for biomedical implants, but its susceptibility to suffer corrosion attack in human body fluid limits its practical use. Thus, alloying Mg with other metal elements is the most effective strategy to improve its mechanical properties and biocompatibility. [...] Read more.

Magnesium (Mg) is a potential candidate for biomedical implants, but its susceptibility to suffer corrosion attack in human body fluid limits its practical use. Thus, alloying Mg with other metal elements is the most effective strategy to improve its mechanical properties and biocompatibility. Herein, we report a Mg-Zn-Co ternary alloy (85-10-5 wt %) synthesized by the mechanical alloying technique. Ball-milling parameters such as ball size and milling time were varied to obtain better alloy properties. After compaction and sintering, the obtained alloy samples were subjected to various characterizations, including grain, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, X-ray diffraction (XRD), microhardness and nanoindentation analyses. In vitro biocompatibility analysis of different alloys was also performed with MC3T3-E1 osteoblasts. Grain analysis confirmed the even dispersion of particles, while SEM analysis showed the formation of laminates, spherical and fine particles with an increase in time and varied ball size. XRD results further confirmed the formation of intermetallic compounds. The microhardness of samples was increased with the increase in milling time. The Young’s modulus of ternary alloys obtained from nanoindentation analysis was comparable to the modulus of human bone. Moreover, in vitro analysis with osteoblasts showed that the developed alloys were noncytotoxic and biocompatible. Full article

(This article belongs to the Special Issue Development and Application of Biodegradable Metals)

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18 pages, 4144 KiB

Open AccessArticle

Development of Closed-Form Equations for Estimating Mechanical Properties of Weld Metals according to Chemical Composition

by Jeong-Hwan Kim, Chang-Ju Jung, Young IL Park and Yong-Taek Shin

Metals 2022, 12(3), 528; https://doi.org/10.3390/met12030528 - 21 Mar 2022

Cited by 3 | Viewed by 1938

Abstract

In this study, data analysis was performed using an artificial neural network (ANN) approach to investigate the effect of the chemical composition of welds on their mechanical properties (yield strength, tensile strength, and impact toughness). Based on the data collected from previously performed [...] Read more.

In this study, data analysis was performed using an artificial neural network (ANN) approach to investigate the effect of the chemical composition of welds on their mechanical properties (yield strength, tensile strength, and impact toughness). Based on the data collected from previously performed experiments, correlations between related variables and results were analyzed and predictive models were developed. Sufficient datasets were prepared using data augmentation techniques to solve problems caused by insufficient data and to make better predictions. Finally, closed-form equations were developed based on the predictive models to evaluate the mechanical properties according to the chemical composition. Full article

(This article belongs to the Special Issue Modelling, Test and Practice of Steel Structures)

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10 pages, 1592 KiB

Open AccessArticle

The Influence of Thermomechanical Treatments on the Structure, Microstructure, and Mechanical Properties of Ti-5Mn-Mo Alloys

by Mariana Luna Lourenço, Fenelon Martinho Lima Pontes and Carlos Roberto Grandini

Metals 2022, 12(3), 527; https://doi.org/10.3390/met12030527 - 21 Mar 2022

Cited by 5 | Viewed by 2093

Abstract

With the increase in the world’s population, the rising number of traffic accidents, and the increase in life expectancy, the need for implants, dental work, and orthopedics is growing ever larger. Researchers are working to improve the biomaterials used for these purposes, improve [...] Read more.

With the increase in the world’s population, the rising number of traffic accidents, and the increase in life expectancy, the need for implants, dental work, and orthopedics is growing ever larger. Researchers are working to improve the biomaterials used for these purposes, improve their functionality, and increase the human body’s life span. Thus, new titanium alloys are being developed, usually with β-stabilizer elements (which decrease the elastic modulus), with the Ti-Mn-Mo alloys being one example of these. This study of the Ti-5Mn-10Mo and Ti-5Mn-15Mo alloys only showed signs of the β phase in the structure and microstructure, presenting a combination of low modulus of elasticity and high corrosion resistance compared to the values of commercial alloys. In this sense, this work presents an analysis of the influence of some thermomechanical treatments, such as homogenization, hot-rolling, solution, and annealing, on the structure, microstructure, and selected mechanical properties of the Ti-5Mn-10Mo and Ti-5Mn-15Mo alloys. Full article

(This article belongs to the Special Issue Innovations in Metallic Biomaterials)

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15 pages, 5372 KiB

Open AccessArticle

Research on High-Temperature Compressive Properties of Ti–10V–1Fe–3Al Alloy

by Cong Li, Can Huang, Zhili Ding and Xing Zhou

Metals 2022, 12(3), 526; https://doi.org/10.3390/met12030526 - 21 Mar 2022

Cited by 2 | Viewed by 1834

Abstract

To investigate the thermal deformation behavior of Ti–10V–2Cr–3Al titanium alloy, the hot compression experiments were carried out via a strain rate of 0.1–0.001 s⁻¹ and deformation temperature of 730~880 °C. The results showed that the rheological stress decreases when the deformation temperature [...] Read more.

To investigate the thermal deformation behavior of Ti–10V–2Cr–3Al titanium alloy, the hot compression experiments were carried out via a strain rate of 0.1–0.001 s⁻¹ and deformation temperature of 730~880 °C. The results showed that the rheological stress decreases when the deformation temperature increases or strain rate decreases. Due to the deformation conditions, some flow curves exhibited significant discontinuous yielding and flow softening. Flow softening in the α+β phase region was dominated by dynamic recrystallization (DRX), while in the β phase region, it was centered on dynamic recovery (DRV). A high-temperature constitutive equation, with good predictive power, was established. Full article

(This article belongs to the Special Issue Development of New Metallic Materials via Macrodesign of Microstructure)

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10 pages, 5102 KiB

Open AccessArticle

Structure and Properties of Metal-Matrix Composites Based on an Inconel 625–TiB₂ System Fabricated by Additive Manufacturing

by Vladimir Promakhov, Alexey Matveev, Olga Klimova-Korsmik, Nikita Schulz, Vladislav Bakhmat, Artem Babaev and Alexander Vorozhtsov

Metals 2022, 12(3), 525; https://doi.org/10.3390/met12030525 - 21 Mar 2022

Cited by 8 | Viewed by 2804

Abstract

This research work studies the structural phase parameters and physicomechanical properties of metal-matrix composite materials based on a Ni–TiB₂ system obtained by additive manufacturing (specifically, direct laser deposition). The properties of the composites obtained were investigated at high temperatures (up to 1000 [...] Read more.

This research work studies the structural phase parameters and physicomechanical properties of metal-matrix composite materials based on a Ni–TiB₂ system obtained by additive manufacturing (specifically, direct laser deposition). The properties of the composites obtained were investigated at high temperatures (up to 1000 °C). The feasibility of the fabrication of a composite nanostructure of alloy with advanced physicomechanical properties was shown. The introduction of reinforcing TiB₂ particles into an Inconel 625 matrix was confirmed to increase the microhardness and tensile strength of the material obtained. Apparently, the composite structure of the samples facilitates the realisation of several strengthening mechanisms: (1) a grain boundary mechanism that causes strengthening and dislocation movement; (2) a mechanism based on the grain structure breakdown and Hall–Petch relationship realisation. Full article

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15 pages, 6088 KiB

Open AccessArticle

Preparation of Ti-46Al-8Nb Alloy Ingots beyond Laboratory Scale Based on BaZrO₃ Refractory Crucible

by Baohua Duan, Lu Mao, Yuchen Yang, Qisheng Feng, Xuexian Zhang, Haitao Li, Lina Jiao, Rulin Zhang, Xionggang Lu, Guangyao Chen and Chonghe Li

Metals 2022, 12(3), 524; https://doi.org/10.3390/met12030524 - 21 Mar 2022

Cited by 4 | Viewed by 2834

Abstract

The high Nb-containing TiAl-based alloy ingot beyond laboratory scale with a composition of Ti-46Al-8Nb (at.%) was prepared by a vacuum induction melting process based on a BaZrO₃ refractory crucible. A round bar ingot with a diameter of 85 mm and a length [...] Read more.

The high Nb-containing TiAl-based alloy ingot beyond laboratory scale with a composition of Ti-46Al-8Nb (at.%) was prepared by a vacuum induction melting process based on a BaZrO₃ refractory crucible. A round bar ingot with a diameter of 85 mm and a length of 430 mm was finally obtained, and the chemical composition, solidification pathway, microstructure and tensile properties of the ingot were investigated. The results show that the deviations of Al and Nb content along a 430 mm long central part of the ingot are approximately ±0.39 at.% and ±0.14 at.%, and the oxygen content in the ingot can be controlled at around 1000 ppm. The structure of the alloy ingot is a full lamellar structure composed of γ and α₂ phases, and the thickness of the lamellae is approximately 0.53 μm. In case of the α₂ phase, the surface content of the ingot is higher than the middle region and the centrical region; also, it indicated a decreasing trend. During cooling, the alloy solidified from a peritectic reaction (L + β→α) rather than the solidified via β phase (β→α). In addition to Al segregation and Nb segregation, β-phase particles associated with γ phase at the triple junction of the colonies were observed. Moreover, the tensile properties of the longitudinal-cut sample in the ingot is significantly better than those of the transverse-cut sample, with a tensile strength of up to as high as 700 MPa and a corresponding fracture elongation of 1.1%. However, the tensile strength of the transverse-cut sample is only 375 MPa, and the fracture elongation is 0.52%. Full article

(This article belongs to the Special Issue Light Alloy and Its Application)

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11 pages, 7333 KiB

Open AccessArticle

Three-Dimensional Morphology and Analysis of Widmanstätten Sideplates Ferrite

by Shengli Cao, Shaowen Wu, Caijun Zhang and Qingjun Zhang

Metals 2022, 12(3), 523; https://doi.org/10.3390/met12030523 - 21 Mar 2022

Cited by 1 | Viewed by 2544

Abstract

The three-dimensional (3D) morphology and crystal structure of Widmanstätten sideplate ferrite were simulated using a focused ion beam (FIB) scanning electron microscope equipped with electron backscatter diffraction (EBSD). The primary Widmanstätten sideplates nucleated and grew directly at the austenite grain boundary (GB). A [...] Read more.

The three-dimensional (3D) morphology and crystal structure of Widmanstätten sideplate ferrite were simulated using a focused ion beam (FIB) scanning electron microscope equipped with electron backscatter diffraction (EBSD). The primary Widmanstätten sideplates nucleated and grew directly at the austenite grain boundary (GB). A certain included angle between the sideplates and the austenite GB was observed. The sideplates grew approximately parallel to the grain, and were separated by a small-angle GB. The primary Widmanstätten sideplates are best described as “∃” shaped, with a long intermediate ferrite strip. The interface with the austenite GB was smooth and flat, and the sideplate surface contained pits and holes. The secondary Widmanstätten sideplates nucleated and grew on the surface of the proeutectoid GB ferrite, with the sideplates and GB ferrite perpendicular to each other. Sideplates parallel to one another grew into the grain, and were separated by small-angle GB. The 3D morphology was distinguished by its “comb” shape. The sideplates’ tail was clustered and its front end remained sharp. The contact side of the GB ferrite was smooth and flat. The surface contained several uneven pits and defects. Full article

(This article belongs to the Special Issue Advances in Refining, Solidification, and Casting of Steels and Alloys)

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13 pages, 3210 KiB

Open AccessFeature PaperArticle

Experimental and Modeling Study of Deformability of Glassy CaO-(MnO)-Al₂O₃-SiO₂ Inclusions

by Qifeng Shu, Chaoge You, Tuomas Alatarvas and Timo Matti Juhani Fabritius

Metals 2022, 12(3), 522; https://doi.org/10.3390/met12030522 - 20 Mar 2022

Cited by 4 | Viewed by 2401

Abstract

The occurrence of non-deformable, non-metallic inclusions is the dominant reason for failure of wire during drawing and degrades service life for some steel grades, e.g., tire cord steel. To investigate the deformability of glassy inclusions in CaO-Al₂O₃-SiO₂ and [...] Read more.

The occurrence of non-deformable, non-metallic inclusions is the dominant reason for failure of wire during drawing and degrades service life for some steel grades, e.g., tire cord steel. To investigate the deformability of glassy inclusions in CaO-Al₂O₃-SiO₂ and MnO-Al₂O₃-SiO₂ systems, experimental and numerical methods were used. Young’s modulus values of some glasses based on the CaO-Al₂O₃-SiO₂ and MnO-Al₂O₃-SiO₂ systems, which correspond to typical inclusions in tire cord steel, were measured with resonant ultrasound spectroscopy. The effect of basicity, defined as the ratio of mass percentage of CaO to SiO₂, on Young’s modulus and Poisson’s ratio were investigated. The Young’s moduli of glasses are enhanced with increasing basicity, which could be attributed to the high field strength of calcium ions. The Poisson’s ratios of glasses also show an increase tendency with increasing basicity, which could be due to the loss of rigidity of network with introduction of calcium ions. The equations in the literature for Young’s modulus calculation were evaluated based on the present and literature data. Appen’s equation is modified by re-fitting the present and literature data to give accurate estimation of Young’s modulus with the mean deviation of 2%. The iso-Young’s modulus diagrams for CaO-Al₂O₃-SiO₂ systems were constructed. It is proposed that the iso-Young’s modulus diagram could be combined with liquid area in CaO-Al₂O₃-SiO₂ ternary phase diagram to optimize the inclusion composition during both hot rolling and cold drawing. Full article

(This article belongs to the Special Issue Inclusion Precipitation during Solidification of Steels)

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17 pages, 6935 KiB

Open AccessArticle

Effect of Corrugated Sheet Diameter on Structural Behavior under Cryogenic Temperature and Hydrodynamic Load

by Jin-Seok Park, Jeong-Hyeon Kim, Yong-Cheol Jeong, Hee-Tae Kim, Seul-Kee Kim and Jae-Myung Lee

Metals 2022, 12(3), 521; https://doi.org/10.3390/met12030521 - 18 Mar 2022

Cited by 2 | Viewed by 2511

Abstract

The most important technical issue in the shipbuilding industry regarding liquefied natural gas (LNG) carrier cargo containment systems (CCS) is securing the structural reliability of the primary barrier, which is in direct contact with the LNG. Fracture of the primary barrier by the [...] Read more.

The most important technical issue in the shipbuilding industry regarding liquefied natural gas (LNG) carrier cargo containment systems (CCS) is securing the structural reliability of the primary barrier, which is in direct contact with the LNG. Fracture of the primary barrier by the hydrodynamic load of the LNG CCS may lead to disasters because it is difficult to implement immediate safety measures in the marine environment, unlike on land. Hence, structural reliability of the LNG membrane is the most critical issue in LNG carrier CCSs, where thin and corrugated 304L stainless steel is often used as the primary barrier to prevent repeated thermal deformation from the temperature difference during loading (−163 °C) and unloading (20 °C) of the LNG. However, plastic deformation of the 1.2 mm-thick corrugated membrane of the LNG CCS has been reported continuously owing to its vulnerability to cryogenic hydrodynamic loads. In the present study, we conducted a parametric analysis to investigate the effects of the corrugation shape as a preliminary study of the primary barrier. Finite element analysis was conducted with a simplified plate to focus on the effects of corrugation. Furthermore, a two-step validation was conducted using the above experimental results to ensure reliability of the structural analysis. The results show that optimizing the corrugation shape could ensure better structural safety than the conventional design. Full article

(This article belongs to the Special Issue Low-Temperature Behavior of Metals)

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10 pages, 6111 KiB

Open AccessArticle

Effects of Extrusion and Rolling Processes on the Microstructure and Mechanical Properties of Zn-Li-Ag Alloys

by Yujiao Lu, Ying Liu, Yilong Dai, Yang Yan and Kun Yu

Metals 2022, 12(3), 520; https://doi.org/10.3390/met12030520 - 18 Mar 2022

Cited by 3 | Viewed by 2965

Abstract

In this work, a novel Zn-0.5%Li-0.1%Ag alloy was cast and extruded into rods, which were rolled into a plate, and the effects of extrusion and rolling on the microstructure and mechanical properties of the Zn-0.5%Li-0.1%Ag alloy were evaluated. The results show that grain [...] Read more.

In this work, a novel Zn-0.5%Li-0.1%Ag alloy was cast and extruded into rods, which were rolled into a plate, and the effects of extrusion and rolling on the microstructure and mechanical properties of the Zn-0.5%Li-0.1%Ag alloy were evaluated. The results show that grain strengthening occurs in all of the alloys because of the presence of nano-LiZn₄ precipitates. The extrusion and rolling processes promote grain size refinement and orientation order, and the microstructure and mechanical properties of the Zn-0.5%Li-0.1%Ag alloy can be significantly improved by secondary processing. The elastic modulus and tensile strength of the processed alloy increased to 83.1 GPa and 251.6 MPa, respectively, compared to 75.6 GPa and 185.8 MPa, respectively, for the as-cast Zn-0.5%Li-0.1%Ag alloy. More importantly, elongation was greatly improved, from 16.9% to 92.6%, which is an increase of up to 448%, and there were transgranular cleavage planes and intergranular cleavage planes in the fracture surfaces. The intergranular cleavage planes were dominant, and they showed ductile fracture characteristics. Full article

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11 pages, 3614 KiB

Open AccessArticle

The Effect of Wall Thickness and Scanning Speed on the Martensitic Transformation and Tensile Properties of Selective Laser Melted NiTi Thin-Wall Structures

by Fangmin Guo, Yanbao Guo, Xiangguang Kong, Zhiwei Xiong and Shijie Hao

Metals 2022, 12(3), 519; https://doi.org/10.3390/met12030519 - 18 Mar 2022

Cited by 5 | Viewed by 2267

Abstract

In this study, we analyzed the coupling effect of laser scanning speed and wall thickness on the phase transformation behavior and tensile properties of selective laser melted NiTi thin-wall structures. It is demonstrated that either scanning speed or wall thickness has their respective [...] Read more.

In this study, we analyzed the coupling effect of laser scanning speed and wall thickness on the phase transformation behavior and tensile properties of selective laser melted NiTi thin-wall structures. It is demonstrated that either scanning speed or wall thickness has their respective influence rule, whereas this influence could be changed when coupling them together; that is, under different scanning speeds, the effect of wall thickness could be different. It is found that the deviation of phase transformation temperature among different wall thicknesses is ~3.7 °C at 400 mm/s, while this deviation increases to ~23.5 °C at 600 mm/s. However, the deviation of phase transformation peak width among different wall thicknesses shows little change under different scanning speeds. At low scanning speed, the samples with thicker wall thickness exhibit better tensile ductility than thinner, whereas they all show poor tensile properties and brittle behavior at high scanning speed. This uncertain influence rule is mainly due to the interaction effect between different thermal histories generated by wall thickness and scanning speed. Full article

(This article belongs to the Special Issue Shape Memory Alloys 2022)

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17 pages, 3872 KiB

Open AccessReview

Review of Thermoplastic Drawing with Bulk Metallic Glasses

by Shweta Jagdale, Akib Jabed, Sumanth Theeda, Chandra Sekhar Meduri, Zhonglue Hu, Molla Hasan and Golden Kumar

Metals 2022, 12(3), 518; https://doi.org/10.3390/met12030518 - 18 Mar 2022

Cited by 13 | Viewed by 3324

Abstract

This study summarizes the recent progress in thermoplastic drawing of bulk metallic glasses. The integration of drawing with templated embossing enables the fabrication of arrays of high-aspect-ratio nanostructures whereas the earlier drawing methodologies are limited to a single fiber. The two-step drawing can [...] Read more.

This study summarizes the recent progress in thermoplastic drawing of bulk metallic glasses. The integration of drawing with templated embossing enables the fabrication of arrays of high-aspect-ratio nanostructures whereas the earlier drawing methodologies are limited to a single fiber. The two-step drawing can produce metallic glass structures such as, vertically aligned nanowires on substrates, nanoscale tensile specimens, hollow microneedles, helical shafts, and micro-yarns, which are challenging to fabricate with other thermoplastic forming operations. These geometries will open new applications for bulk metallic glasses in the areas of sensors, optical absorption, transdermal drug-delivery, and high-throughput characterization of size-effects. In this article, we review the emergence of template-based thermoplastic drawing in bulk metallic glasses. The review focuses on the development of experimental set-up, the quantitative description of drawing process, and the versatility of drawing methodology. Full article

(This article belongs to the Topic Advanced Forming Technology of Metallic Materials)

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10 pages, 2677 KiB

Open AccessArticle

Evolution of Nanostructured Carbon Coatings Quality via RT-CVD and Their Tribological Behavior on Nodular Cast Iron

by Alejandra Moreno-Bárcenas, Jesus Alejandro Arizpe Zapata, Miguel Ángel Esneider Alcalá, Jaime Téllez Ramírez, Antonio Magaña Hernández and Alejandra García-García

Metals 2022, 12(3), 517; https://doi.org/10.3390/met12030517 - 18 Mar 2022

Cited by 1 | Viewed by 2521

Abstract

One of the most critical problems in industry is the wear of materials. Graphene, as a tribological coating, has shown a tremendous impact on sliding surfaces. In this work, a few layers of graphene were grown on a nodular cast iron substrate, a [...] Read more.

One of the most critical problems in industry is the wear of materials. Graphene, as a tribological coating, has shown a tremendous impact on sliding surfaces. In this work, a few layers of graphene were grown on a nodular cast iron substrate, a material used in camshafts. The studied synthesis parameters in a rapid thermal chemical vapor deposition (CVD) furnace and the quality of the final coating are presented. The influence of hydrogen flow and cooling rate was evaluated, obtaining the best results in the few layers of graphene structure and deposition at 10 sccm and 4 °C/min. A standard ball-on-disk tribometer was used to assess the coefficient of friction on a few layers of graphene on nodular cast iron substrates. Laboratory test results show that the few layers of graphene coating resulted in a 60% reduction in coefficient of friction and close to a 70% reduction in volume removed versus the uncoated substrates. The surface of the substrate was not modified before a few layers of graphene growth to have a working surface close to camshafts obtained by the industrial process at ARBOMEX SA de CV. Full article

(This article belongs to the Topic Materials and Surface Treatment Processes Used for Engineering Applications)

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10 pages, 2308 KiB

Open AccessArticle

Martensitic Transformation and Barocaloric Effect in Co-V-Ga-Fe Paramagnetic Heusler Alloy

by Jie Liu, Zhe Li, Hongwei Liu, Litao Yu, Yuanlei Zhang, Yiming Cao, Kun Xu and Yongsheng Liu

Metals 2022, 12(3), 516; https://doi.org/10.3390/met12030516 - 17 Mar 2022

Cited by 6 | Viewed by 2503

Abstract

In the present study, polycrystalline Co₅₀V₃₄Ga_16−xFe_x (

1 \leq x \leq 2

) quaternary Heusler alloys were fabricated by the arc-melting method. It was found that they undergo a paramagnetic martensitic transformation (MT) from the [...] Read more.

In the present study, polycrystalline Co₅₀V₃₄Ga_16−xFe_x (

1 \leq x \leq 2

) quaternary Heusler alloys were fabricated by the arc-melting method. It was found that they undergo a paramagnetic martensitic transformation (MT) from the L2₁-type cubic austenitic structure to the D0₂₂ tetragonal martensitic structure. With the increase of the Fe concentration, the MT shifts towards a higher temperature range, which is strongly related to the variation of the valence electron concentration. Moreover, it was also found that the MT exhibited by every alloy is sensitive to the applied hydrostatic pressure due to a relatively high difference in volume between the two phases. By using the quasi-direct method based on caloric measurements, the barocaloric effect (BCE) associated with the hydrostatic pressure-driven MT was estimated in the studied alloys. The results demonstrated that the sample with

x = 1.5

performs an optimal BCE among these three alloys. Full article

(This article belongs to the Special Issue Novel Shape Memory Alloys)

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15 pages, 50896 KiB

Open AccessArticle

Effect of Ultrasonic Nanocrystal Surface Modification Treatment at Room and High Temperatures on the High-Frequency Fatigue Behavior of Inconel 718 Fabricated by Laser Metal Deposition

by Ruslan M. Karimbaev, In Sik Cho, Young Sik Pyun and Auezhan Amanov

Metals 2022, 12(3), 515; https://doi.org/10.3390/met12030515 - 17 Mar 2022

Cited by 8 | Viewed by 2468

Abstract

In this work, the effect of ultrasonic nanocrystal surface modification (UNSM) treatment at room and high temperatures (RT and HT) on the high-frequency fatigue behavior of Inconel 718 alloy fabricated by laser metal deposition (LMD) process was experimentally investigated. UNSM treatment at RT [...] Read more.

In this work, the effect of ultrasonic nanocrystal surface modification (UNSM) treatment at room and high temperatures (RT and HT) on the high-frequency fatigue behavior of Inconel 718 alloy fabricated by laser metal deposition (LMD) process was experimentally investigated. UNSM treatment at RT and HT modified a surface morphology and produced a nanostructured surface layer with a thickness of approximately 120 and 140 µm, respectively. The surface roughness of the untreated sample was reduced, while the surface hardness was notably increased after the UNSM treatment at RT and HT. Both increased with increasing the UNSM treatment temperature. Fatigue behavior of the untreated samples at various stress levels was slightly improved after the UNSM treatment at RT and HT. This is mainly due to the formation of a fine grained nanostructured surface layer with reduced porosity and highly induced compressive residual stress. Fatigue mechanisms of the samples were comprehensively discussed based on the quantitative SEM fractographic analysis. Full article

(This article belongs to the Special Issue Surface Modification of Metallic Materials for Wear and Fatigue)

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6 pages, 1353 KiB

Open AccessCommunication

Revealing the Role of Cross Slip for Serrated Plastic Deformation in Concentrated Solid Solutions at Cryogenic Temperatures

by Aditya Srinivasan Tirunilai, Klaus-Peter Weiss, Jens Freudenberger, Martin Heilmaier and Alexander Kauffmann

Metals 2022, 12(3), 514; https://doi.org/10.3390/met12030514 - 17 Mar 2022

Cited by 1 | Viewed by 2031

Abstract

Serrated plastic deformation is an intense phenomenon in CoCrFeMnNi at and below 35 K with stress amplitudes in excess of 100 MPa. While previous publications have linked serrated deformation to dislocation pile ups at Lomer–Cottrell (LC) locks, there exist two alternate models on [...] Read more.

Serrated plastic deformation is an intense phenomenon in CoCrFeMnNi at and below 35 K with stress amplitudes in excess of 100 MPa. While previous publications have linked serrated deformation to dislocation pile ups at Lomer–Cottrell (LC) locks, there exist two alternate models on how the transition from continuous to serrated deformation occurs. One model correlates the transition to an exponential LC lock density–temperature variation. The second model attributes the transition to a decrease in cross-slip propensity based on temperature and dislocation density. In order to evaluate the validity of the models, a unique tensile deformation procedure with multiple temperature changes was carried out, analyzing stress amplitudes subsequent to temperature changes. The analysis provides evidence that the apparent density of LC locks does not massively change with temperature. Instead, the serrated plastic deformation is likely related to cross-slip propensity. Full article

(This article belongs to the Special Issue Mechanical Behavior of Metallic Materials under Different Loading Conditions)

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15 pages, 4768 KiB

Open AccessArticle

Constitutive Modeling on the Ti-6Al-4V Alloy during Air Cooling and Application

by Xiaoning Han, Junzhou Yang, Jinshan Li and Jianjun Wu

Metals 2022, 12(3), 513; https://doi.org/10.3390/met12030513 - 17 Mar 2022

Cited by 4 | Viewed by 2009

Abstract

The flow behavior of a Ti-6Al-4V alloy has been investigated and modeled, with the aim of exploring the damage mechanism and distortion of a sandwich structure during the air cooling process after superplastic forming (SPF). The selected temperature range was 930–700 °C, and [...] Read more.

The flow behavior of a Ti-6Al-4V alloy has been investigated and modeled, with the aim of exploring the damage mechanism and distortion of a sandwich structure during the air cooling process after superplastic forming (SPF). The selected temperature range was 930–700 °C, and the strain rates were 10⁻², 10⁻³, and 10⁻⁴/s. An Arrhenius model was employed to describe the yield stress at a strain of 0.1, and a simple generalized reduced gradient refinement was applied to optimize the parameters for a constitutive model. The mean error between the predicted and experimental flow stress was 65% and 16% before and after parameter optimization, respectively. The effects of strain on flow stress showed a linear relationship, so a strain compensation method was proposed. The modified Arrhenius model developed in this paper provided a good agreement between the predicted stresses and the experimental data. Finally, a finite element analysis (FEA) with a “UHARD” subroutine was employed, and the results indicated that the inner plate of the sandwich structure was the most vulnerable location during the air cooling process, and that the engineering strain due to a non-uniform temperature was calculated as 0.37%. Full article

(This article belongs to the Special Issue Innovative and Flexible Sheet Forming Technologies)

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15 pages, 6777 KiB

Open AccessArticle

The Effect of Ce on the Microstructure, Superplasticity, and Mechanical Properties of Al-Mg-Si-Cu Alloy

by Andrey G. Mochugovskiy, Alexey S. Prosviryakov, Nataliya Yu. Tabachkova and Anastasia V. Mikhaylovskaya

Metals 2022, 12(3), 512; https://doi.org/10.3390/met12030512 - 17 Mar 2022

Cited by 6 | Viewed by 2599

Abstract

The current study focuses on the influence of Ce on the superplastic behavior, microstructure, and mechanical properties of the Al-Mg-Si-Cu-Zr-Sc alloy. The multilevel microstructural analysis including light, scanning electron, and transmission electron microscopies was carried out. The simple thermomechanical treatment including the hot [...] Read more.

The current study focuses on the influence of Ce on the superplastic behavior, microstructure, and mechanical properties of the Al-Mg-Si-Cu-Zr-Sc alloy. The multilevel microstructural analysis including light, scanning electron, and transmission electron microscopies was carried out. The simple thermomechanical treatment including the hot and cold rolling resulted in fragmentation of the eutectic originated particles of the Ce-bearing phases. The two-step annealing of the ingots provided the precipitation of the L1₂-structured Al₃(Sc,Zr) phase dispersoids with 10 nm mean size and a high number density. Due to the particle stimulated nucleation (PSN) effect caused by the particles of eutectic origin, and Zener pinning effect provided by nanoscale dispersoids of L1₂-structured phases, the studied alloy demonstrated good superplastic properties. Full article

(This article belongs to the Special Issue Advances in Casting, Thermomechanical and Heat Treatments of Aluminum Alloy)

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20 pages, 28971 KiB

Open AccessArticle

The Formation Mechanisms and Evolution of Multi-Phase Inclusions in Ti-Ca Deoxidized Offshore Structural Steel

by Zhe Rong, Hongbo Liu, Peng Zhang, Feng Wang, Geoff Wang, Baojun Zhao, Fengqiu Tang and Xiaodong Ma

Metals 2022, 12(3), 511; https://doi.org/10.3390/met12030511 - 17 Mar 2022

Cited by 3 | Viewed by 2075

Abstract

To understand and clarify the formation mechanisms and evolution of complex inclusions in Ti-Ca deoxidized offshore structural steel, inclusions in industrial steel were systematically investigated. The number density of total inclusions generally decreased from Ladle Furnace (LF), Vacuum Degassing (VD), Tundish to the [...] Read more.

To understand and clarify the formation mechanisms and evolution of complex inclusions in Ti-Ca deoxidized offshore structural steel, inclusions in industrial steel were systematically investigated. The number density of total inclusions generally decreased from Ladle Furnace (LF), Vacuum Degassing (VD), Tundish to the final product except for Ti and Ca addition. The major inclusions during the refining process were CaO-Al₂O₃-SiO₂-(MgO)-TiO_x and CaO-Al₂O₃-SiO₂. CaO-Al₂O₃-SiO₂-(MgO)-TiO_x inclusion initially originated from the combination of CaO-SiO₂-(MgO) in refining slag or refractory and deoxidization product Al₂O₃ and TiO₂. With the refining process proceeding and Ca addition, the Al₂O₃ concentration in the CaO-Al₂O₃-SiO₂-(MgO)-TiO_x inclusions gradually dropped while the CaO and TiO₂ concentrations gradually increased. The CaO-Al₂O₃-SiO₂ inclusions originally came from refining slag, existing as 2CaO∙ Al₂O₃∙ SiO₂, and maintained a liquid state during the early stage of LF. After Ca treatment, it was gradually transferred to 2CaO∙ SiO₂ due to Al₂O₃ continuously being reduced by Ca. The liquidus of 2CaO∙ SiO₂ inclusion was higher than that of molten steel, so they presented as a solid-state during the refining process. After welding thermal simulation, CaO-Al₂O₃-SiO₂-(MgO)-TiO_x inclusions were proven effective for inducing intragranular acicular ferrite (IAF) while CaO-Al₂O₃-SiO₂ was inert for IAF promotion. Additionally, Al₂O₃-MgO spinel in multiphase CaO-Al₂O₃-SiO₂-(MgO)-TiO_x inclusion has different formation mechanisms: (1) initial formation as individual Al₂O₃-MgO spinel as a solid-state in molten steel; (2) and it presented as a part of liquid inclusion CaO-Al₂O₃-SiO₂-(MgO)-TiO_x and firstly precipitated due to its low solubility. Full article

(This article belongs to the Special Issue Fundamentals of Advanced Pyrometallurgy)

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10 pages, 4819 KiB

Open AccessArticle

Microstructure and Fracture Performance of Wire Arc Additively Manufactured Inconel 625 Alloy by Hot-Wire GTAW

by Xiaoli Wang, Qingxian Hu, Tianqing Li, Wenkang Liu, Douxi Tang, Zichen Hu and Kang Liu

Metals 2022, 12(3), 510; https://doi.org/10.3390/met12030510 - 17 Mar 2022

Cited by 12 | Viewed by 2835

Abstract

In this work, an Inconel 625 thin-wall structure was fabricated by the gas tungsten arc welding (GTAW) hot-wire arc additive manufacturing process. The microstructure and mechanical properties of the Inconel 625 samples, extracted from different orientations and locations of the thin-wall structure, were [...] Read more.

In this work, an Inconel 625 thin-wall structure was fabricated by the gas tungsten arc welding (GTAW) hot-wire arc additive manufacturing process. The microstructure and mechanical properties of the Inconel 625 samples, extracted from different orientations and locations of the thin-wall structure, were investigated and compared. The results showed that the additively manufactured Inconel 625 component, made by hot-wire GTAW, had good quality. Its microstructure consisted of dendrites, equiaxial crystals, and cellular crystals. The average hardness from the bottom to the top was similar, indicating that the thin wall had good consistency. The plasticity in the deposition direction was better than those in the other three regions, which was related to the dendritic structure in the sedimentary direction. Full article

(This article belongs to the Special Issue Light Alloy and Its Application)

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23 pages, 9506 KiB

Open AccessArticle

Numerical Study on the Influence of Distributing Chamber Volume on Metallurgical Effects in Two-Strand Induction Heating Tundish

by Bin Yang, Anyuan Deng, Xiaolei Kang, Pengfei Duan and Engang Wang

Metals 2022, 12(3), 509; https://doi.org/10.3390/met12030509 - 16 Mar 2022

Cited by 4 | Viewed by 1974

Abstract

Reducing the volume of distributing chamber by shortening its width is one of the ways to obtain good metallurgical effects for a large two-strand induction heating tundish. A multi-field coupling numerical model was established to figure out the effect of distributing chamber volume [...] Read more.

Reducing the volume of distributing chamber by shortening its width is one of the ways to obtain good metallurgical effects for a large two-strand induction heating tundish. A multi-field coupling numerical model was established to figure out the effect of distributing chamber volume on the flow field, temperature field of molten steel, and removal of inclusions. Three tundishes with distributing chamber widths of 1.216 m (tundish A), 0.838 m (tundish B), and 0.606 m (tundish C) were modeled. The results indicated that reducing the width of the distributing chamber from 1.216 m to 0.838 and 0.606 m could improve the fastest heating rate from 0.4 K/min to 0.6 and 0.8 K/min and reduce the energy consumption from 476 kWh to 444 and 434 kWh. The temperature fluctuation of molten steel in the distributing chamber rose with the decrease in distributing chamber volume during the continuous casting process. Besides, tundish B performs the best temperature uniformity. The flow field in the distributing chamber was no longer symmetrical, and a short-circuit flow appeared when the width was reduced to 0.606 m. As a result, the floating ratio and removal ratio of inclusions decreased and the ratio of inclusions flowing into the mold sharply increased in tundish C. When the width was reduced from 1.216 to 0.838 m, the floating ratio of inclusions had little change and the removal ratio increased slightly. The floating efficiency increased with the decrease in the volume of distributing chamber, and the removal efficiency is the highest in tundish B. Taken together, tundish B should be adopted. Full article

(This article belongs to the Section Computation and Simulation on Metals)

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21 pages, 7954 KiB

Open AccessArticle

Evaluation of Tannins as Potential Green Corrosion Inhibitors of Aluminium Alloy Used in Aeronautical Industry

by Carla Sofia Proença, Bruno Serrano, Jorge Correia and Maria Eduarda Machado Araújo

Metals 2022, 12(3), 508; https://doi.org/10.3390/met12030508 - 16 Mar 2022

Cited by 23 | Viewed by 4427

Abstract

In this work some organic natural products were studied, namely tannic acid, gallic acid, mimosa tannin and chestnut tannin, as potential green corrosion inhibitors of the aluminium alloy AA2024-T3. The anodizing treatment was performed in a solution of the referred organic compounds in [...] Read more.

In this work some organic natural products were studied, namely tannic acid, gallic acid, mimosa tannin and chestnut tannin, as potential green corrosion inhibitors of the aluminium alloy AA2024-T3. The anodizing treatment was performed in a solution of the referred organic compounds in diluted sulfuric acid. The electrochemical impedance spectroscopy and the potentiodynamic polarization were performed to assess sealing quality and corrosion protection granted by the anodic films. To understand the green inhibitors; interaction with the metal surface, FTIR spectra of anodizing and anodizing and sealed samples of AA2023-T3 were recorded, and the shifts in the position of the major bands confirmed that the green inhibitor interacts with the metal surface. Images of the morphology of the coatings were provided by Scanning Electron Microscopy. From the results obtained through the various techniques that were used to carry out this study it is possible to conclude that the formed anodic films can be a good contribution for the prevention of corrosion in the aluminium alloy AA2024-T3. Full article

(This article belongs to the Topic Green Corrosion Inhibitors for Metallic Materials)
(This article belongs to the Section Corrosion and Protection)

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14 pages, 2007 KiB

Open AccessArticle

Influence of Carbon and Oxygen on the Core Structure and Peierls Stress of Screw Dislocation in Molybdenum

by Zi-Qi Wang, Yu-Hao Li, Guang-Hong Lu and Hong-Bo Zhou

Metals 2022, 12(3), 507; https://doi.org/10.3390/met12030507 - 16 Mar 2022

Cited by 4 | Viewed by 2338

Abstract

The plasticity and hardness of metals are largely dependent on how dislocation interacts with solute atoms. Here, taking bcc molybdenum (Mo) as the example, the interaction of interstitial solutes carbon (C) and oxygen (O) with screw dislocation, and their influences on the dislocation [...] Read more.

The plasticity and hardness of metals are largely dependent on how dislocation interacts with solute atoms. Here, taking bcc molybdenum (Mo) as the example, the interaction of interstitial solutes carbon (C) and oxygen (O) with screw dislocation, and their influences on the dislocation motion, have been determined using first-principles calculations and thermodynamic models. Due to the incompact atomic structure and variation of electronic states in the dislocation core, C and O will segregate from the bulk system to the dislocation region. Notably, the presence of C/O at the dislocation induces the reconstruction of the core structure, from an easy-core to hard-core configuration. This originates from the fact that the hard-core structure provides a larger available volume at the interstitial site than the easy-core structure and, thus, facilitates the dissolution of C and O. More importantly, the addition of C/O in the dislocation significantly increases the Peierls stresses and double-kink formation enthalpies of screw dislocation in Mo, from 1.91 GPa and 1.18 eV for C/O-free dislocation to 5.63/4.69 GPa and 1.77/1.58 eV for C/O-saturated dislocation. Therefore, these interstitial solutes have a pinning effect on the dislocation motion, and this effect becomes stronger with higher segregating levels. This work reveals the profound effect of interstitial solutes on the properties of the dislocation core and provides a fundamental factor to account for the interstitial solutes-related phenomena in bcc metals. Full article

(This article belongs to the Section Computation and Simulation on Metals)

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23 pages, 4761 KiB

Open AccessArticle

Research on Fatigue Life Prediction Method of Key Component of Turning Mechanism Based on Improved TCD

by Tingting Wang, Han Zhang, Yuechen Duan, Mengjian Wang and Dongchen Qin

Metals 2022, 12(3), 506; https://doi.org/10.3390/met12030506 - 16 Mar 2022

Cited by 3 | Viewed by 2385

Abstract

The main objective of this paper is to accurately obtain fatigue life prediction for the key components of a turning mechanism using the improved theory of critical distances (TCD). The irregularly shaped rotating arm is the central stressed part of the turning mechanism, [...] Read more.

The main objective of this paper is to accurately obtain fatigue life prediction for the key components of a turning mechanism using the improved theory of critical distances (TCD). The irregularly shaped rotating arm is the central stressed part of the turning mechanism, which contains notches. It has been found that TCD achieves good results in predicting the fatigue strength or fatigue life of notched components with regular shape but is less commonly used for notched components with irregular shape. Therefore, TCD was improved and applied broadly to predict the fatigue life of an irregularly shaped rotating arm. Firstly, the notch depth and structure net width parameters were introduced into the low-order and low-accuracy classical TCD function to obtain a novel stress function with high computational efficiency and high accuracy, whereas the stress concentration factor was introduced to modify the length of critical distance. Secondly, the improved TCD was used to predict the fatigue strength of notched components with regular shape, and its accuracy was demonstrated by a fatigue experiment. Finally, the improved TCD was applied to predict the fatigue life of an irregularly shaped rotating arm. The deviation between prediction results and experimental results is less than 18%. The results demonstrate that the improved TCD can be applied effectively and accurately to predict the fatigue life of key components of turning mechanisms. Full article

(This article belongs to the Topic Fatigue and Fracture Assessment of Structural Components and Materials)

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26 pages, 11013 KiB

Open AccessArticle

Experimental and Numerical Simulation of the Dynamic Response of a Stiffened Panel Suffering the Impact of an Ice Indenter

by Tongqiang Yu, Jiaxia Wang, Junjie Liu and Kun Liu

Metals 2022, 12(3), 505; https://doi.org/10.3390/met12030505 - 16 Mar 2022

Cited by 3 | Viewed by 2441

Abstract

At a laboratory scale, the response of a stiffened panel subjected to the impact of an ice indenter was studied by both experimental and numerical means. The experiment was conducted using a Falling Weight Impact Tester, and the impact force and deformation data [...] Read more.

At a laboratory scale, the response of a stiffened panel subjected to the impact of an ice indenter was studied by both experimental and numerical means. The experiment was conducted using a Falling Weight Impact Tester, and the impact force and deformation data of the stiffened panel were measured and recorded. The experimental results showed that the ice indenter could cause significant indentation to the stiffened panel and experienced severe crushing and scattering itself. Finite element analysis was performed to reproduce the structural deformations in an appropriate manner, and a constitutive model with a multisurface yield criterion and a dynamic empirical failure criterion for ice material was developed. Good agreement was obtained, and the influences of various parameters in the constitutive model and the performance of other different material models are discussed. The purpose of this study is to present an experimental and numerical study on a scenario of high-energy collision between a hull structure and an ice block, the conclusions of which can be very useful for studying ship-ice collisions and guiding engineering applications. Full article

(This article belongs to the Special Issue Special Materials for Shipbuilding)

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80 pages, 209653 KiB

Open AccessReview

Casting Defects in Sand-Mold Cast Irons—An Illustrated Review with Emphasis on Spheroidal Graphite Cast Irons

by Jon Sertucha and Jacques Lacaze

Metals 2022, 12(3), 504; https://doi.org/10.3390/met12030504 - 16 Mar 2022

Cited by 21 | Viewed by 24068

Abstract

Cast irons are known to be easy to shape by sand casting due to their high eutectic fraction. Despite this fact, together with cost benefits, obtaining good quality castings is not an easy task, although it depends on the level of defects allowed [...] Read more.

Cast irons are known to be easy to shape by sand casting due to their high eutectic fraction. Despite this fact, together with cost benefits, obtaining good quality castings is not an easy task, although it depends on the level of defects allowed in each case. Casting defects are here reviewed and classified into three classes according to their known main origin: (1) related to the sand mixtures used to make the molds; (2) associated with the mold design and the geometry of the castings; (3) related to the casting alloy itself. The present work is an illustrated description of these defects, with details of their origin when well established, and of known remedies. In addition, an attempt has been made to clarify the possible cross-effects of the above three origins. Full article

(This article belongs to the Special Issue Optimizing Techniques and Understanding in Casting Processes)

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20 pages, 9463 KiB

Open AccessArticle

Selection of Higher Order Lamb Wave Mode for Assessment of Pipeline Corrosion

by Donatas Cirtautas, Vykintas Samaitis, Liudas Mažeika, Renaldas Raišutis and Egidijus Žukauskas

Metals 2022, 12(3), 503; https://doi.org/10.3390/met12030503 - 16 Mar 2022

Cited by 15 | Viewed by 3072

Abstract

Hidden corrosion defects can lead to dangerous accidents such as leakage of toxic materials causing extreme environmental and economic consequences. Ultrasonic guided waves showed good potential detecting distributed corrosion in pipeline networks at sufficiently large distances. To simplify signal analysis, traditional guided wave [...] Read more.

Hidden corrosion defects can lead to dangerous accidents such as leakage of toxic materials causing extreme environmental and economic consequences. Ultrasonic guided waves showed good potential detecting distributed corrosion in pipeline networks at sufficiently large distances. To simplify signal analysis, traditional guided wave methods use low frequencies where only fundamental modes exist; hence, the small, localized defects are usually barely detectable. Novel techniques frequently use higher order guided wave modes that propagate around the circumference of the pipe and are more sensitive to the localized changes in the wall thickness. However current high order mode guided wave technology commonly uses either non-dispersive shear modes or higher order mode cluster (HOMC) waves that are mostly sensitive to surface defects. As the number of application cases of high order modes to corrosion detection is still limited, a huge potential is available to seek for other modes that can offer improved resolution and sensitivity to localized corrosion type defects. The objective of this work was to investigate higher order modes for corrosion detection and to determine the most promising ones in sense of excitability, leakage losses, propagation distance, and potential simplicity in the analysis. The selection of the proper mode is discussed with the support of phase and group velocity dispersion curves, out of plane and in plane distributions over the thickness and on surface of the sample, and leakage losses due to water load. The analysis led to selection of symmetric S₃ mode, while the excitation of it was demonstrated through finite element simulations, taking into account the size of phased array aperture and apodization law and considering two-sided mode generation. Finally, theoretical estimations were confirmed with experiments, demonstrating the ability to generate and receive selected mode. It was shown that S₃ mode is a good candidate for corrosion screening around the circumference of the pipe, as it has sufficient propagation distance, can be generated with conventional ultrasonic (UT) phased arrays, has sufficiently high group velocity to be distinguished from co-existing modes, and is sensitive to the loss of wall thickness. Full article

(This article belongs to the Special Issue Modern Non-destructive Testing for Metallic Materials)

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31 pages, 102999 KiB

Open AccessEditor’s ChoiceReview

The Influence of Precipitation, High Levels of Al, Si, P and a Small B Addition on the Hot Ductility of TWIP and TRIP Assisted Steels: A Critical Review

by Barrie Mintz and Abdullah Qaban

Metals 2022, 12(3), 502; https://doi.org/10.3390/met12030502 - 16 Mar 2022

Cited by 14 | Viewed by 2971

Abstract

The hot ductility of Transformation Induced Plasticity (TRIP) and Twinning Induced Plasticity (TWIP) steels is reviewed, concentrating on the likelihood of cracking occurring on continuous casting during the straightening operation. In this review, the influence of high levels of Al, Si, P, Mn [...] Read more.

The hot ductility of Transformation Induced Plasticity (TRIP) and Twinning Induced Plasticity (TWIP) steels is reviewed, concentrating on the likelihood of cracking occurring on continuous casting during the straightening operation. In this review, the influence of high levels of Al, Si, P, Mn and C on their hot ductility will be discussed as well as the important role B can play in improving their hot ductility. Of these elements, Al has the worst influence on ductility but a high Al addition is often needed in both TWIP and TRIP steels. AlN precipitates are formed often as thin coatings covering the austenite grain surfaces favouring intergranular failure and making them difficult to continuous cast without cracks forming. Furthermore, with TWIP steels the un-recrystallised austenite, which is the state the austenite is when straightening, suffers from excessive grain boundary sliding, so that the ductility often decreases with increasing temperature, resulting in the RA value being below that needed to avoid cracking on straightening. Fortunately, the addition of B can often be used to remedy the deleterious influence of AlN. The influence of precipitation hardeners (Nb, V and Ti based) in strengthening the room temperature yield strength of these TWIP steels and their influence on hot ductility is also discussed. Full article

(This article belongs to the Special Issue Continuous Casting and Hot Ductility of Advanced High-Strength Steels)

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23 pages, 7806 KiB

Open AccessFeature PaperReview

Recent Progress with BCC-Structured High-Entropy Alloys

by Fangfei Liu, Peter K. Liaw and Yong Zhang

Metals 2022, 12(3), 501; https://doi.org/10.3390/met12030501 - 16 Mar 2022

Cited by 61 | Viewed by 9679

Abstract

High-entropy alloys (HEAs) prefer to form single-phase solid solutions (body-centered cubic (BCC), face-centered cubic (FCC), or hexagonal closed-packed (HCP)) due to their high mixing entropy. In this paper, we systematically review the mechanical behaviors and properties (such as oxidation and corrosion) of BCC-structured [...] Read more.

High-entropy alloys (HEAs) prefer to form single-phase solid solutions (body-centered cubic (BCC), face-centered cubic (FCC), or hexagonal closed-packed (HCP)) due to their high mixing entropy. In this paper, we systematically review the mechanical behaviors and properties (such as oxidation and corrosion) of BCC-structured HEAs. The mechanical properties at room temperature and high temperatures of samples prepared by different processes (including vacuum arc-melting, powder sintering and additive manufacturing) are compared, and the effect of alloying on the mechanical properties is analyzed. In addition, the effects of HEA preparation and compositional regulation on corrosion resistance, and the application of high-throughput techniques in the field of HEAs, are discussed. To conclude, alloy development for BCC-structured HEAs is summarized. Full article

(This article belongs to the Special Issue Amorphous and High-Entropy Alloy Coatings)

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Metals, Volume 12, Issue 3 (March 2022) – 163 articles

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