Feature Papers in Metal Failure Analysis

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

Deadline for manuscript submissions: closed (30 November 2023) | Viewed by 7303

Special Issue Editors

Laboratory of Mechanical Properties of Nanostructured Materials and Superalloys, Belgorod National Research University, Pobeda 85, Belgorod 308015, Russia
Interests: structural steels and alloys; microstructure; grain boundaries; dislocation substructure; deformation and annealing behavior; strength and plasticity
Special Issues, Collections and Topics in MDPI journals
Laboratory of Mechanical Properties of Nanostructured Materials and Superalloys, Belgorod National Research University, Pobeda 85, Belgorod 308015, Russia
Interests: structural and functional alloys; deformation microstructures; strain hardening; dispersion strengthening; heat treatment; aging; grain growth and recrystallization
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

We are pleased to announce the launch of this Special Issue devoted to metal failure analysis. Fracture behavior is one of the most important aspects affecting the mechanical performance of metals and alloys. Failure analysis is especially important for structural materials as their fracture may have terrible consequences. Progress in the development of safe and sound constructions requires comprehensive investigation of fracture mechanisms, effects of internal stresses, and microstrains on crack nucleation and propagation. Thus, studying the microstructural mechanisms underlying the fracture mechanics is of great practical importance. The aim of this Special Issue, “Feature Papers in Metal Failure Analysis”, is to highlight the current achievements in theoretical and experimental investigations of fracture behavior and its effect on mechanical performance of various metallic materials, focusing on the hottest success in analyzing the crack nucleation and propagation in metals and alloys under cyclic or monotonous loading as well as during exploitation. Papers dealing with experimental investigation, simulation, and analysis of failure of structural steels and alloys are also welcome.

Dr. Andrey Belyakov
Dr. Anna Morozova
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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

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

Keywords

  • metals and alloys
  • mechanical behavior
  • fatigue
  • toughness
  • fracture mechanics
  • strength and plasticity
  • crack/void nucleation and propagation

Published Papers (8 papers)

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Research

14 pages, 11711 KiB  
Article
Effect of Friction Stir Welding and Tempering on the Microstructure and Strength of a Tempformed Low-Alloy Steel
Metals 2024, 14(1), 114; https://doi.org/10.3390/met14010114 - 17 Jan 2024
Viewed by 609
Abstract
The microstructure developed in a low-alloy steel during friction stir welding and post-weld tempering was studied. The quenched steel samples were subjected to tempering at 650 °C for 1 h, followed by warm rolling to a total strain of 1.5 at the same [...] Read more.
The microstructure developed in a low-alloy steel during friction stir welding and post-weld tempering was studied. The quenched steel samples were subjected to tempering at 650 °C for 1 h, followed by warm rolling to a total strain of 1.5 at the same temperature. The processed steel samples were characterized by an ultrafine-grained microstructure of the lamellar type with a transverse grain size of 360 nm and exhibited an yield strength of about 1200 MPa and a total elongation of 13%. Then, the steel plates were joined by friction stir welding. The yield strength of the weld joint was about 1170 MPa, although the total elongation decreased to 1.5%. The martensite microstructure, with a high-angle grain boundary spacing of about 800 nm, was developed in the stir zone. This martensite in the stir zone originated from the ultrafine-grained prior austenite, resulting in an almost two-fold increase in hardness as compared to the base material. Tempering of the welded sample at 650 °C for 1 h resulted in a decrease in the hardness of the weld joint to the level of the base material. Nevertheless, the fracture of the welded and tempered sample occurred in the base material. The yield strength of the welded sample after tempering was 930 MPa, with a total elongation of 13%. Full article
(This article belongs to the Special Issue Feature Papers in Metal Failure Analysis)
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22 pages, 12175 KiB  
Article
Effect of Fe-Bearing Phases on the Mechanical Properties and Fracture Mechanism of Al–2wt.%Cu–1.5wt.%Mn (Mg,Zn) Non-Heat Treatable Sheet Alloy
Metals 2023, 13(11), 1911; https://doi.org/10.3390/met13111911 - 20 Nov 2023
Viewed by 767
Abstract
The effects of Fe-bearing phases on the structure, mechanical properties, and fracture mechanism of a non-heat-treatable model sheet alloy (wt.%: Al–2%Cu–1.5%Mn(-Mg,Zn)), designed for Al20Cu2Mn3 dispersoids, was investigated. This involved a combination of thermodynamic modeling in the Thermo-Calc program [...] Read more.
The effects of Fe-bearing phases on the structure, mechanical properties, and fracture mechanism of a non-heat-treatable model sheet alloy (wt.%: Al–2%Cu–1.5%Mn(-Mg,Zn)), designed for Al20Cu2Mn3 dispersoids, was investigated. This involved a combination of thermodynamic modeling in the Thermo-Calc program and experimental studies of structure and mechanical properties. It has been shown that the addition of 0.5 and 0.4% iron and silicon leads to the formation of eutectic inclusions in the Al15(Mn,Fe)3Si2 phase. In addition to the Fe- bearing inclusions, the formation of the eutectic Al2Cu and Al2CuMg phases can be expected in the as-cast structure of the experimental alloys. Despite their relatively high fraction of eutectic particles, non-homogenized alloy ingots demonstrated sufficiently high deformation processability during the hot (400 °C) and cold rolling, which made it possible to obtain high-quality sheet alloys (with reduction degrees of 80 and 75%, respectively). The results of the tensile tests revealed that, after cold rolling, the addition of 1% Mg significantly increased the tensile and yield strengths, whereas the effect of 1% Zn was negligible. At the same time, the uniform distribution of Fe-bearing phases in the structure of the cold-rolled sheets contributes to the preservation of the dimple mechanism of the fracture toughness. This helps to maintain the same level of ductility for the cold-rolled sheet Fe-containing alloys as for Fe-free alloys. It has been shown, based on the data obtained, that adding Fe, Si, Mg, and Zn to the base Al–2%Cu–1.5%Mn alloy in a total amount of more than 3% makes it possible to retain the ductile fracture patterns of the base alloy and obtain a fairly higher level of mechanical properties. This suggests the fundamental possibility of using a variety of secondary raw materials (containing the main elements present in aluminum alloys of different alloying systems) to prepare a base alloy that does not require homogenization or thermal hardening. Full article
(This article belongs to the Special Issue Feature Papers in Metal Failure Analysis)
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13 pages, 7060 KiB  
Article
Failure of Elliptical Tubes with Different Long–Short Axis Ratios under Cyclic Bending in Different Directions
Metals 2023, 13(11), 1891; https://doi.org/10.3390/met13111891 - 14 Nov 2023
Viewed by 515
Abstract
Although elliptical tubes are stronger and more stable than circular tubes, few studies have fully considered the behavior of elliptical tubes under cyclic bending loads. This study experimentally investigated the response and failure of SUS304 stainless steel elliptical tubes with four different ratios [...] Read more.
Although elliptical tubes are stronger and more stable than circular tubes, few studies have fully considered the behavior of elliptical tubes under cyclic bending loads. This study experimentally investigated the response and failure of SUS304 stainless steel elliptical tubes with four different ratios of long and short axes (1.5, 2.0, 2.5, and 3.0) under cyclic bending along four different orientation angles (0°, 30°, 60°, and 90°). The wall thickness was 0.7 mm, and cyclic bending was applied until buckling failure occurred. The moment–curvature curves exhibited cyclic hardening, and stable loops were formed for all long–short axis ratios and orientation angles. Increasing the long–short axis ratio slightly decreased the peak bending moment while increasing the orientation angle increased the peak bending moment. For a given orientation angle, the curves relating the short-axis variation (i.e., change in length divided by the original length of the short axis) and curvature demonstrated symmetry, serrations, and a growth pattern as the number of cycles increased regardless of the long–short axis ratio. At long–short axis ratios of 2.0, 2.5, and 3.0, these curves even exhibited a butterfly-like trend. Increasing the long–short axis ratio increased the short-axis variation, while increasing the orientation angle decreased the short-axis variation. Regarding the curves relating the curvature and number of cycles required to initiate buckling, for each orientation angle, the four long–short axis ratios corresponded to four straight lines when plotted on double-logarithmic co-ordinates. Based on the experimental results, empirical equations are proposed to describe the above relationships. The empirical equations were applied to predicting experimental data and showed close agreement. Full article
(This article belongs to the Special Issue Feature Papers in Metal Failure Analysis)
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17 pages, 15964 KiB  
Article
Effect of Rotary Swaging on Microstructure and Properties of Cr-Ni-Ti Austenitic Stainless Steel
Metals 2023, 13(10), 1760; https://doi.org/10.3390/met13101760 - 17 Oct 2023
Viewed by 667
Abstract
In this study, Cr-Ni-Ti austenitic stainless steel was subjected to rotary swaging in various modes, followed by annealing. The effect of processing conditions on the resulting microstructure and, therefore, on the mechanical properties under static and cyclic loading was studied. After RS the [...] Read more.
In this study, Cr-Ni-Ti austenitic stainless steel was subjected to rotary swaging in various modes, followed by annealing. The effect of processing conditions on the resulting microstructure and, therefore, on the mechanical properties under static and cyclic loading was studied. After RS the formation of an ultrafine-grained predominantly twinned structure, with structural elements sized between 100–250 nm in Cr-Ni-Ti stainless steel, was observed. The stepwise temperature reduction during rotary swaging allows the manipulation of the microstructure transformations, which eventually leads to the desired properties of the steel. As a result, the ultimate tensile strength increased from 610 MPa to 1304 MPa when the elongation decreased from 40% to 10.5%, and the fatigue limit increased from 425 MPa to 700 MPa. The Cr-Ni-Ti steel is strengthened through the formation of an ultrafine-grained structure, twinning in austenite, and martensitic transformation. Subsequent annealing at a temperature 475 °C triggers the active precipitation of nanosized TiC carbides in the deformed steel. On one hand, the presence of these carbides increases the tensile strength up to 1938 Mpa, while on the other hand, slows down crack propagation with a slight decrease in ductility (ε = 8%) of the deformed sample. At the same time, dispersion hardening does not affect the fatigue limit of steel. Full article
(This article belongs to the Special Issue Feature Papers in Metal Failure Analysis)
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10 pages, 3673 KiB  
Communication
Contact Fatigue Behavior Evolution of 18CrNiMo7-6 Gear Steel Based on Surface Integrity
Metals 2023, 13(9), 1605; https://doi.org/10.3390/met13091605 - 17 Sep 2023
Viewed by 1053
Abstract
In this work, the surface integrity (surface morphology, microstructure, microhardness, residual stress) of contact fatigue (CF) samples with different numbers of running cycles was comprehensively studied. Based on typical working conditions, a fatigue life evaluation method was proposed based on the evolution law [...] Read more.
In this work, the surface integrity (surface morphology, microstructure, microhardness, residual stress) of contact fatigue (CF) samples with different numbers of running cycles was comprehensively studied. Based on typical working conditions, a fatigue life evaluation method was proposed based on the evolution law of surface integrity. The CF with different numbers of running cycles revealed that the average grain size decreased with the increase in the number of running cycles, and the surface microhardness, residual stress and surface roughness Ra increased first and then decreased. In addition, the relationships between different surface integrity parameters and fatigue life were plotted. Moreover, based on the fatigue life profiles, the running state and remaining life of gear samples can be evaluated. Full article
(This article belongs to the Special Issue Feature Papers in Metal Failure Analysis)
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18 pages, 10535 KiB  
Article
A Molecular Dynamics Simulation to Shed Light on the Mechanical Alloying of an Al-Zr Alloy Induced by Severe Plastic Deformation
Metals 2023, 13(9), 1595; https://doi.org/10.3390/met13091595 - 14 Sep 2023
Viewed by 786
Abstract
In a recent experimental work, as a result of severe plastic deformation, a non-equilibrium solid solution was obtained despite the very limited solubility of zirconium (Zr) in aluminum (Al). This opens up a new path in the development of heat-treatable alloys with improved [...] Read more.
In a recent experimental work, as a result of severe plastic deformation, a non-equilibrium solid solution was obtained despite the very limited solubility of zirconium (Zr) in aluminum (Al). This opens up a new path in the development of heat-treatable alloys with improved electrical and mechanical properties, where mechanically dissolved elements can form intermetallic particles that contribute to precipitation strengthening. In the present study, molecular dynamics simulations were performed to better understand the process of mechanical dissolution of Zr within an Al model, with Zr atoms segregated along its grain boundaries. Stress–strain curves, radial distribution functions, and mechanisms of plastic deformation and dissolution of Zr in Al were analyzed. It is revealed that orientation of the grain boundary with segregation normal to the shear direction promotes more efficient mixing of alloy components compared to its parallel arrangement. This happens because in the second case, grain boundary sliding is the main deformation mechanism, and Zr tends to remain within the interfaces. In contrast, the involvement of dislocations in the case of normal orientation of grain boundaries with Zr segregation significantly contributes to deformation and facilitates better dissolution of Zr in the Al matrix. The findings obtained can provide new insights considering the role of texture during mechanical alloying of strongly dissimilar metals. Full article
(This article belongs to the Special Issue Feature Papers in Metal Failure Analysis)
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22 pages, 9986 KiB  
Article
Influence of Quenching and Subsequent Artificial Aging on Tensile Strength of Laser-Welded Joints of Al–Cu–Li Alloy
Metals 2023, 13(8), 1393; https://doi.org/10.3390/met13081393 - 03 Aug 2023
Viewed by 804
Abstract
The research aim was to optimize post-weld heat-treatment (PWHT) modes for a laser-welded joint of the Al–Cu–Li alloy and improve their respective strength properties. As a result, the ultimate tensile strength, yield point, and elongation of the joint were enhanced up to 95%, [...] Read more.
The research aim was to optimize post-weld heat-treatment (PWHT) modes for a laser-welded joint of the Al–Cu–Li alloy and improve their respective strength properties. As a result, the ultimate tensile strength, yield point, and elongation of the joint were enhanced up to 95%, 94%, and 38%, respectively, of those inherent in the base metal. Before and after PWHT, both microstructures and phase compositions have been examined by optical and scanning electron microscopy, as well as synchrotron X-ray diffractometry. In the as-welded metal, the α-Al and T1(Al2CuLi) phases were found, along with the θ′(Al2Cu) and S′(Al2CuMg) phases localized at the grain boundaries, significantly reducing the mechanical properties of the joint. Upon quenching, the agglomerates dissolved at the grain boundaries, the solid solution was homogenized, and both Guinier–Preston zones and precipitates of the intermediate metastable θ″ phase were formed. After subsequent optimal artificial aging, the (predominant) hardening θ′ and (partial) T1(Al2CuLi) phases were observed in the weld metal, which contributed to the improvement of the strength properties of the joint. Full article
(This article belongs to the Special Issue Feature Papers in Metal Failure Analysis)
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15 pages, 4192 KiB  
Article
Tempering Behavior of Novel Low-Alloy High-Strength Steel
Metals 2022, 12(12), 2177; https://doi.org/10.3390/met12122177 - 17 Dec 2022
Cited by 8 | Viewed by 1434
Abstract
The effect of tempering on the mechanical properties, structure, and dispersion of secondary phase particles is studied in 0.4%C-2%Si-1%Cr-1%Mo-VNb steel. This steel austenitized at 900 °C with subsequent water quenching exhibits a yield stress of 1445 MPa and a lath martensite structure with [...] Read more.
The effect of tempering on the mechanical properties, structure, and dispersion of secondary phase particles is studied in 0.4%C-2%Si-1%Cr-1%Mo-VNb steel. This steel austenitized at 900 °C with subsequent water quenching exhibits a yield stress of 1445 MPa and a lath martensite structure with MX particles of ~40 nm located in matrix and boundary M6C carbides of ~210 nm. Tempering in the temperature interval of 200–400 °C provides a yield stress of 1625 MPa due to the precipitation of ε-carbide and cementite within laths. The yield stress decreases to 1415 and 1310 MPa after tempering at 500 and 650 °C, respectively, due to the replacement of matrix carbides by boundary M23C6 carbide. A Charpy V-notch impact energy of ~12 J/cm2 is almost independent from tempering temperatures of up to 400 °C and increases up to ~33 J/cm2 after tempering at 650 °C due to decreased yield stresses and increased plasticity. Full article
(This article belongs to the Special Issue Feature Papers in Metal Failure Analysis)
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