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Manufacturing and Fatigue Properties of Materials

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Manufacturing Processes and Systems".

Deadline for manuscript submissions: closed (10 February 2023) | Viewed by 34707

Special Issue Editors

Department of Production Engineering and Safety, Czestochowa University of Technology, St. J.H. Dabrowskiego 69, 42-201 Czestochowa, Poland
Interests: manufacturing; processing; technology; fatigue; fracture; quality systems; process improvement
Special Issues, Collections and Topics in MDPI journals
Department of Materials Sciences, Faculty of Mechanical Engineering, University of Žilina, Univerzitná 1, 01026 Žilina, Slovak Republic
Interests: degradation martials; fatigue; crack propagations; stress corrosion crackin; fractures; contact fatigue; fretting; non-conventional technologies
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Fatigue of materials is a complex phenomenon affected by many factors. Structural design, material properties, and manufacturing processing belong among the most important factors influencing the fatigue lifetime of engineering structures and machine parts. In the machinery industry, raw materials are transformed into final products with required physical properties through a series of technological processes.

This Special Issue of Materials is dedicated to the study of fatigue phenomena of structural materials in connection with the influence of various methods of classical or newest manufacturing processing and special treatments. Researchers from the academic and industrial sphere are invited to publish results of their research and latest achievements in this field.

Research works that focus on progressive materials and technologies, new characterization techniques for study of the relationship between microstructure and fatigue properties, and also physical and numerical simulation studies are especially encouraged.

In general, original studies that include various technological factors influencing quality and fatigue properties of structural materials, e.g., technological parameters, influence of heat treatment, surface treatment, surface finish, cold work, and so on are particularly welcome. The different perspectives (used technology, technological properties, alloy or composite material design, microstructural features, structural integrity, low-cycle or high-cycle fatigue, fatigue crack initiation or growth, fracture behavior, and stress concentration factors) can be assumed. Some review articles are also welcome.

Prof. Robert Ulewicz
Prof. František Nový
Guest Editors

Manuscript Submission Information

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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. Materials is an international peer-reviewed open access semimonthly 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

  • manufacturing
  • processing
  • technology
  • fatigue
  • fracture

Published Papers (17 papers)

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Research

18 pages, 5413 KiB  
Article
Training Deep Neural Networks with Novel Metaheuristic Algorithms for Fatigue Crack Growth Prediction in Aluminum Aircraft Alloys
by Muhammad Hamza Zafar, Hassaan Bin Younis, Majad Mansoor, Syed Kumayl Raza Moosavi, Noman Mujeeb Khan and Naureen Akhtar
Materials 2022, 15(18), 6198; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15186198 - 06 Sep 2022
Cited by 3 | Viewed by 1345
Abstract
Fatigue cracks are a major defect in metal alloys, and specifically, their study poses defect evaluation challenges in aluminum aircraft alloys. Existing inline inspection tools exhibit measurement uncertainties. The physical-based methods for crack growth prediction utilize stress analysis models and the crack growth [...] Read more.
Fatigue cracks are a major defect in metal alloys, and specifically, their study poses defect evaluation challenges in aluminum aircraft alloys. Existing inline inspection tools exhibit measurement uncertainties. The physical-based methods for crack growth prediction utilize stress analysis models and the crack growth model governed by Paris’ law. These models, when utilized for long-term crack growth prediction, yield sub-optimum solutions and pose several technical limitations to the prediction problems. The metaheuristic optimization algorithms in this study have been conducted in accordance with neural networks to accurately forecast the crack growth rates in aluminum alloys. Through experimental data, the performance of the hybrid metaheuristic optimization–neural networks has been tested. A dynamic Levy flight function has been incorporated with a chimp optimization algorithm to accurately train the deep neural network. The performance of the proposed predictive model has been tested using 7055 T7511 and 6013 T651 alloys against four competing techniques. Results show the proposed predictive model achieves lower correlation error, least relative error, mean absolute error, and root mean square error values while shortening the run time by 11.28%. It is evident through experimental study and statistical analysis that the crack length and growth rates are predicted with high fidelity and very high resolution. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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22 pages, 4269 KiB  
Article
Analysis of Cutting Stability of a Composite Variable-Section Boring Bar with a Large Length-to-Diameter Ratio Considering Internal Damping
by Jingmin Ma, Jianfeng Xu, Longfei Li, Xingguang Liu and Ming Gao
Materials 2022, 15(15), 5465; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15155465 - 08 Aug 2022
Cited by 2 | Viewed by 1373
Abstract
Chattering in composite deep-hole boring can directly affect surface processing quality and efficiency and has always been a research hotspot in machining mechanics. In this study, based on Euler–Bernoulli beam theory, the fine control equations for the cutting stability of composite variable-section boring [...] Read more.
Chattering in composite deep-hole boring can directly affect surface processing quality and efficiency and has always been a research hotspot in machining mechanics. In this study, based on Euler–Bernoulli beam theory, the fine control equations for the cutting stability of composite variable-section boring bars were established using the Hamilton principle, in which the sectional change and internal damping of the material were considered. Next, using the Galerkin method and semi-discrete method, the effects of the taper ratio, damping ratio, length-to-diameter ratio, and ply angle on the free vibration characteristics and cutting stability were analyzed in detail. The results show that at a low damping ratio, both the first-order inherent frequency and boring stability can be enhanced with the increase in the taper ratio; at a large damping ratio, increasing the taper ratio can reduce the first-order inherent frequency and boring stability. Finally, the effects of the sectional change on the inherent frequency, displacement response, and convergence were analyzed. A numerical simulation was performed for the model reliability validation. The present research results can provide a theoretical basis and technical guidance for analyzing the cutting stability and fine control of composite variable-section boring bars with large length-to-diameter ratios. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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15 pages, 12307 KiB  
Article
FEM Simulation of the Riveting Process and Structural Analysis of Low-Carbon Steel Tubular Rivets Fracture
by Jaroslaw Jan Jasinski and Michal Tagowski
Materials 2022, 15(1), 374; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15010374 - 05 Jan 2022
Cited by 4 | Viewed by 2281
Abstract
Riveted joints are a common way to connect elements and subassemblies in the automotive industry. In the assembly process, tubular rivets are loaded axially with ca. 3 kN forces, and these loads can cause cracks and delamination in the rivet material. Such effects [...] Read more.
Riveted joints are a common way to connect elements and subassemblies in the automotive industry. In the assembly process, tubular rivets are loaded axially with ca. 3 kN forces, and these loads can cause cracks and delamination in the rivet material. Such effects at the quality control stage disqualify the product in further assembly process. The article presents an analysis of the fracture mechanism of E215 low-carbon steel tubular rivets used to join modules of driver and passenger safety systems (airbags) in vehicles. Finite element method (FEM) simulation and material testing were used to verify the stresses and analysis of the rivet fracture. Numerical tests determined the state of stress during rivet forming using the FEM-EA method based on the explicit integration of central differences. Light microscopy (LM), scanning electron microscopy (SEM) and chemical composition analysis (SEM-EDS) were performed to investigate the microstructure of the rivet material and to analyze the cracks. Results showed that the cause of rivet cracking is the accumulation and exceeding of critical tensile stresses in the rivet flange during the tube processing and the final riveting (forming) process. Moreover, it was discovered that rivet fracture is largely caused by structural defects (tertiary cementite Fe,Mn3CIII along the boundaries of prior austenite grains) in the material resulting from the incorrectly selected parameters of the final heat treatment of the prefabricate (tube) from which the rivet was produced. The FEM simulation of the riveting and structural characterization results correlated well, so the rivet forming process and fracture mechanism could be fully investigated. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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15 pages, 9923 KiB  
Article
Analysis of the Influence of Surface Modifications on the Fatigue Behavior of Hot Work Tool Steel Components
by Thomas Wild, Timo Platt, Dirk Biermann and Marion Merklein
Materials 2021, 14(23), 7324; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14237324 - 30 Nov 2021
Cited by 6 | Viewed by 2315
Abstract
Hot work tool steels (HWS) are widely used for high performance components as dies and molds in hot forging processes, where extreme process-related mechanical and thermal loads limit tool life. With the functionalizing and modification of tool surfaces with tailored surfaces, a promising [...] Read more.
Hot work tool steels (HWS) are widely used for high performance components as dies and molds in hot forging processes, where extreme process-related mechanical and thermal loads limit tool life. With the functionalizing and modification of tool surfaces with tailored surfaces, a promising approach is given to provide material flow control resulting in the efficient die filling of cavities while reducing the process forces. In terms of fatigue properties, the influence of surface modifications on surface integrity is insufficiently studied. Therefore, the potential of the machining processes of high-feed milling, micromilling and grinding with regard to the implications on the fatigue strength of components made of HWS (AISI H11) hardened to 50 ± 1 HRC was investigated. For this purpose, the machined surfaces were characterized in terms of surface topography and residual stress state to determine the surface integrity. In order to analyze the resulting fatigue behavior as a result of the machining processes, a rotating bending test was performed. The fracture surfaces were investigated using fractographic analysis to define the initiation area and to identify the source of failure. The investigations showed a significant influence of the machining-induced surface integrity and, in particular, the induced residual stress state on the fatigue properties of components made of HWS. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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16 pages, 4387 KiB  
Article
Assessment of the Post-Cracking Fatigue Behavior of Steel and Polyolefin Fiber-Reinforced Concrete
by Alejandro Enfedaque, Marcos G. Alberti, Jaime C. Gálvez and Jhonatan Santiago Proaño
Materials 2021, 14(22), 7087; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14227087 - 22 Nov 2021
Cited by 2 | Viewed by 1259
Abstract
Some types of fiber-reinforced concrete (FRC) such as steel fiber-reinforced concrete (SFRC) or polyolefin fiber-reinforced concrete (PFRC) are suitable for structural uses but there is still scarce knowledge regarding their flexural fatigue behavior. This study aimed to provide some insight into the matter [...] Read more.
Some types of fiber-reinforced concrete (FRC) such as steel fiber-reinforced concrete (SFRC) or polyolefin fiber-reinforced concrete (PFRC) are suitable for structural uses but there is still scarce knowledge regarding their flexural fatigue behavior. This study aimed to provide some insight into the matter by carrying out flexural fatigue tests in pre-cracked notched specimens that previously reached the Service Limit State (SLS) or the Ultimate Limit State (ULS). The fatigue cycles applied between 30% and 70% of the pre-crack load at 5 Hz until the collapse of the material or until 1,000,000 cycles were reached. The results showed that the fatigue life of PFRC both at SLS or ULS was remarkably higher than the correspondent of SFRC. The fracture surface analysis carried out found a linear relation between the fibers present in the fracture surface and the number of cycles that both SFRC and PFRC could bear. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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16 pages, 7818 KiB  
Article
Abrasive Wear of High-Carbon Low-Alloyed Austenite Steel: Microhardness, Microstructure and X-ray Characteristics of Worn Surface
by Michail Nikolaevich Brykov, Taisiia Oleksandrivna Akrytova, Michail Jurievich Osipov, Ivan Petryshynets, Viktor Puchy, Vasily Georgievich Efremenko, Kazumichi Shimizu, Maik Kunert and Olaf Hesse
Materials 2021, 14(20), 6159; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14206159 - 17 Oct 2021
Cited by 4 | Viewed by 2014
Abstract
A high-carbon, high-silicon steel (1.21 wt% C, 2.56 wt% Mn, 1.59 wt% Si) was subjected to quenching from 900 and 1000 °C, resulting in microstructures containing 60 and 94% of retained austenite, respectively. Subsequent abrasive wear tests of quenched samples were performed using [...] Read more.
A high-carbon, high-silicon steel (1.21 wt% C, 2.56 wt% Mn, 1.59 wt% Si) was subjected to quenching from 900 and 1000 °C, resulting in microstructures containing 60 and 94% of retained austenite, respectively. Subsequent abrasive wear tests of quenched samples were performed using two-body abrasion and three-body abrasion testing machines. Investigations on worn surface and subsurface were carried out using SEM, XRD, and microhardness measurement. It was found that the highest microhardness of worn surface (about 1400 HV0.05) was achieved on samples quenched from 900 °C after three-body abrasion. Microhardness of samples after two-body abrasion was noticeably smaller. with a maximum of about 1200 HV0.05. This difference correlates with microstructure investigations along with XRD results. Three-body abrasion has produced a significantly deeper deformed layer; corresponding diffractograms show bigger values of the full width at half maximum parameter (FWHM) for both α and γ alone standing peaks. The obtained results are discussed in the light of possible differences in abrasive wear conditions and differing stability of retained austenite after quenching from different temperatures. It is shown that a structure of metastable austenite may be used as a detector for wear conditions, as the sensitivity of such austenite to phase transformation strongly depends on wear conditions, and even small changes in the latter lead to significant differences in the properties of the worn surface. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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16 pages, 10036 KiB  
Article
Corrosion Fatigue Damages of Rebars under Loading in Time
by Yaroslav Blikharskyy, Jacek Selejdak and Nadiia Kopiika
Materials 2021, 14(12), 3416; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14123416 - 20 Jun 2021
Cited by 24 | Viewed by 2116
Abstract
Nowadays, a relatively small number of studies concern the study of corrosion processes in reinforced concrete structures under load. Additionally, rather little research has been carried out concerning changes in the stress–strain state parameters of structures under the simultaneous action of aggressive environment [...] Read more.
Nowadays, a relatively small number of studies concern the study of corrosion processes in reinforced concrete structures under load. Additionally, rather little research has been carried out concerning changes in the stress–strain state parameters of structures under the simultaneous action of aggressive environment and load. This issue requires additional experimental and theoretical investigation. Determination of mechanical properties, fatigue characteristics and susceptibility to corrosion cracking was performed on samples of reinforcing St3GPF steel. The chemical composition of steel was determined by structural analysis. The spectral method for the determination of alloying elements and impurities in steels is based on the excitation of iron atoms and admixtures by electric discharge, decomposition of radiation into a spectrum, followed by its registration on photoplate with the use of electrograph. Experimental tests of samples in an aggressive environment under the action of statically applied tensile force showed that corrosion damage has little effect on the strength characteristics. At the same time, the decrease in area reduction and the decrease in strain were recorded. Additionally, the action of cyclic loads in an aggressive environment leads to a significant reduction in the fatigue limit to values from 20 to 24% of the yield strength of the original samples, which is 2–3 times lower than the fatigue limit of undamaged samples. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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16 pages, 17146 KiB  
Article
Fracture Analysis of High-Strength Screw for Highway Construction
by Andrej Dubec, Petra Kováčiková, Jan Krmela, Vladimíra Krmelová and Artem Artyukhov
Materials 2021, 14(7), 1599; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14071599 - 25 Mar 2021
Cited by 4 | Viewed by 1853
Abstract
High-strength screws represent one of the main joining or fastening components which are commonly used in the process of installation of frame constructions for information boards or signposts, relating to the traffic roads. The control of the production process may not always be [...] Read more.
High-strength screws represent one of the main joining or fastening components which are commonly used in the process of installation of frame constructions for information boards or signposts, relating to the traffic roads. The control of the production process may not always be a sufficient method for ensuring road safety. The backward investigation and control of the screw material processing seems to be the one of the most important procedures when there is the occurrence of any failure during the operation of the screw. This paper is mainly focused on the analysis of the failure of the high-strength screw of 10.9 grade with M diameter of 27 × 3 and a shank length of 64 mm. The mentioned and investigated screw was used as a fastener in a highway frame construction. In the paper, there is mainly the analysis of the material for a broken screw in terms of the material micropurity, the material microstructure, the surface treatment as well as chemical composition. The evaluation was based on investigation by optical microscopy, scanning electron microscopy and energy dispersive spectroscopy. Important knowledge and results were also obtained due to information on micromorphology and material contrast of the fracture surface resulting from fractographic analysis, using the method of scanning electron microscopy. In the case of the production of the high-strength screws, the tempering stands for the decisive or crucial process of heat treatment because the given process can ensure a decrease in hardness, while the required ductile properties of the material are kept and this is also reflected in the increase of strength and micromorphology of the fracture surface. From the aspect of micropurity, inclusions of critical size or distribution were not identified in the material, referring to Czech standard ČSN ISO 4967 (420471). The microstructure corresponds to tempered martensite, but the fracture surface of the broken screw was based on an intercrystalline micromechanism, which is undesirable for the given type of component. Combined with the measurement of the HV1 (Vickers hardness at a load of 1 kg) from the edge to the central area of the screw, the analysis revealed the significant drawbacks in the heat treatment of the high-strength screw. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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17 pages, 4476 KiB  
Article
Analysis of the Welding Type and Filler Metal Influence on Performance of a Regenerated Gear
by Svetislav Marković, Dušan Arsić, Ružica R. Nikolić, Vukić Lazić, Nada Ratković, Branislav Hadzima, Janusz Szmidla and Robert Ulewicz
Materials 2021, 14(6), 1496; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14061496 - 18 Mar 2021
Cited by 4 | Viewed by 1635
Abstract
This paper presents the results of voluminous experimental investigations conducted to analyze the influence of the welding procedure on the performance of regenerated gears. Cylindrical spur gears were tested, both newly manufactured and regenerated, in two fundamentally different ways: by hard facing (surfacing) [...] Read more.
This paper presents the results of voluminous experimental investigations conducted to analyze the influence of the welding procedure on the performance of regenerated gears. Cylindrical spur gears were tested, both newly manufactured and regenerated, in two fundamentally different ways: by hard facing (surfacing) with the “hard” filler metal (DUR 600-IG) and with the “soft” filler metal (EVB2CrMo) with subsequent cementation and quenching. The regeneration procedures were defined and executed, while, subsequently, the microstructure and microhardness of the hard-faced layers were established and measured, followed by checking the durability of the hard-faced teeth flanks. Finally, techno-economic analysis was performed to establish the rationality of the conducted regenerations, i.e., the costs of regenerated and newly manufactured teeth were compared. Based on the results of the conducted investigations, it was possible to establish the influence of the welding type on the performance characteristics (primarily the service life) of the regenerated gears. For individual reparatory hard facing, the procedure with the “hard” filler metal exhibited better characteristics, while for batch reparation of numerous damaged gears, the reparation with the “soft” filler metal, followed by cementation and heat treatment, might be more convenient. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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17 pages, 10850 KiB  
Article
Residual Stress Distribution Design for Gear Surfaces Based on Genetic Algorithm Optimization
by Zhou Chen, Yibo Jiang, Zheming Tong and Shuiguang Tong
Materials 2021, 14(2), 366; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14020366 - 13 Jan 2021
Cited by 17 | Viewed by 1994
Abstract
The rolling contact fatigue of gear surfaces in a heavy loader gearbox is investigated under various working conditions using the critical plane-based multiaxial Fatemi–Socie criterion. The mechanism for residual stress to increase the fatigue initiation life is that the compressive residual stress has [...] Read more.
The rolling contact fatigue of gear surfaces in a heavy loader gearbox is investigated under various working conditions using the critical plane-based multiaxial Fatemi–Socie criterion. The mechanism for residual stress to increase the fatigue initiation life is that the compressive residual stress has a negative normal component on the critical plane. Based on this mechanism, the genetic algorithm is used to search the optimum residual stress distribution that can maximize the fatigue initiation life for a wide range of working conditions. The optimum residual stress distribution is more effective in increasing the fatigue initiation life when the friction coefficient is larger than its critical value, above which the fatigue initiation moves from the subsurface to the surface. Finally, the effect on the fatigue initiation life when the residual stress distribution deviates from the optimum distribution is analyzed. A sound physical explanation for this effect is provided. This yields a useful guideline to design the residual stress distribution. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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16 pages, 1064 KiB  
Article
A New Shear Strength Criterion for Rock Masses with Non-Persistent Discontinuities Considering the Nonlinear Progressive Failure Process
by Bowen Zheng, Shengwen Qi, Songfeng Guo, Xiaolin Huang, Ning Liang, Yu Zou and Guangming Luo
Materials 2020, 13(21), 4694; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13214694 - 22 Oct 2020
Cited by 5 | Viewed by 1514
Abstract
The shear strength characteristics of rock masses containing non-persistent discontinuities are strongly affected by discontinuities and rock bridges. The linear Jennings criterion cannot reflect the nonlinear mechanical behavior during progressive failure of rock masses with non-persistent discontinuities. In this study, a new nonlinear [...] Read more.
The shear strength characteristics of rock masses containing non-persistent discontinuities are strongly affected by discontinuities and rock bridges. The linear Jennings criterion cannot reflect the nonlinear mechanical behavior during progressive failure of rock masses with non-persistent discontinuities. In this study, a new nonlinear shear strength criterion was developed. First of all, a series of shear test data about artificial rock mass samples were collected on the basis of the published literatures, and five types of samples were differentiated according to the positions of discontinuities. After that, a new nonlinear shear strength criterion was proposed by introducing two correction coefficients A and B into the basic form of the Jennings criterion, which could correct the weight of the cohesion and the internal friction coefficient of rock bridges respectively. Then, the new criterion was determined by fitting the basic form of the Jennings criterion with the laboratory data. It was found that the parameters A and B had a nonlinear exponential and negative exponential relation with the connectivity rate respectively. It indicated that both the cohesion and the internal friction coefficient estimated by the new criterion were superior to those estimated by the Jennings criterion. Compared with the linear Jennings criterion, the new nonlinear shear strength criterion had a better applicability. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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14 pages, 8900 KiB  
Article
Profile and Areal Surface Parameters for Fatigue Fracture Characterisation
by Wojciech Macek, Ricardo Branco, Mirosław Szala, Zbigniew Marciniak, Robert Ulewicz, Norbert Sczygiol and Piotr Kardasz
Materials 2020, 13(17), 3691; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13173691 - 20 Aug 2020
Cited by 36 | Viewed by 2911
Abstract
Post-mortem characterisation is a pivotal tool to trace back to the origin of structural failures in modern engineering analyses. This work compared both the crack propagation and rupture roughness profiles based on areal parameters for total fracture area. Notched and smooth samples made [...] Read more.
Post-mortem characterisation is a pivotal tool to trace back to the origin of structural failures in modern engineering analyses. This work compared both the crack propagation and rupture roughness profiles based on areal parameters for total fracture area. Notched and smooth samples made of weather-resistant structural steel (10HNAP), popular S355J2 structural steel and aluminium alloy AW-2017A under bending, torsion and combined bending–torsion were investigated. After the fatigue tests, fatigue fractures were measured with an optical profilometer, and the relevant surface parameters were critically compared. The results showed a great impact of the loading scenario on both the local profiles and total fracture areas. Both approaches (local and total fracture zones) for specimens with different geometries were investigated. For all specimens, measured texture parameters decreased in the following order: total area, rupture area and propagation area. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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11 pages, 2014 KiB  
Article
Spot-Weld Service Life Estimate Based on Application of the Interfacial Crack Concept
by Ružica R. Nikolić, Jelena M. Djoković, Branislav Hadzima and Robert Ulewicz
Materials 2020, 13(13), 2976; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13132976 - 03 Jul 2020
Cited by 10 | Viewed by 1781
Abstract
In the automotive industry, spot-welding is the most common method of joining components. Thus, determining the service life of spot-welds is of great importance in designing assemblies or structures. It is well-known that lately there has been a trend in the industry toward [...] Read more.
In the automotive industry, spot-welding is the most common method of joining components. Thus, determining the service life of spot-welds is of great importance in designing assemblies or structures. It is well-known that lately there has been a trend in the industry toward reducing the fuel consumption and harmful gasses emissions, as well as the weight of structures with the application of the lightweight materials, like aluminum alloys. In this paper, research is presented on the behavior of a spot-weld between the plates made of the two dissimilar materials—aluminum alloy and steel. In addition, the influence of the plates’ thickness and the weld nugget’s diameter on welds’ service life is presented. In this analysis, a concept of the interface crack between the two linear elastic materials was applied. Obtained results show that the plates’ thickness and the nugget’s size, as well as the working load, impose significant influences on the service life of a spot-weld between the two dissimilar materials. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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19 pages, 9004 KiB  
Article
Load Direction-Dependent Influence of Forming-Induced Initial Damage on the Fatigue Performance of 16MnCrS5 Steel
by Kerstin Moehring and Frank Walther
Materials 2020, 13(12), 2680; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13122680 - 12 Jun 2020
Cited by 4 | Viewed by 1856
Abstract
Forming processes influence the mechanical properties of manufactured workpieces in general and by means of forming-induced initial damage in particular. The effect of the latter on performance capability is the underlying research aspect for the investigations conducted. In order to address this aspect, [...] Read more.
Forming processes influence the mechanical properties of manufactured workpieces in general and by means of forming-induced initial damage in particular. The effect of the latter on performance capability is the underlying research aspect for the investigations conducted. In order to address this aspect, fatigue tests under compressive, tensile and compressive-tensile loads were set-up with discrete block-by-block increased amplitudes and constant amplitudes, and performed up to fracture or distinct lifetimes. Aiming at the correlation of the macroscale mechanical testing results at the mesoscale, intensive metallographic investigations of cross-sections using the microscopical methods of secondary electron analysis, energy dispersive spectroscopy and electron backscatter diffraction were performed. Thereby, the correlation of forming-induced initial damage and fatigue performance was determined, the relevance of compressive loads for the cyclic damage evolution was shown, and material anisotropy under compressive loads was indicated. Finally, the need was addressed to perform further investigations regarding crack propagations and crack arrest investigations in order to clarify the mechanism by which initial damage affects cyclic damage evolution. The relevance of the principal stress axis relative to the extrusion direction was emphasized and used as the basis of an argument for investigations under load paths with different stress directions. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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17 pages, 28054 KiB  
Article
Performance-Related Characterization of Forming-Induced Initial Damage in 16MnCrS5 Steel under a Torsional Forward-Reverse Loading Path at LCF Regime
by Kerstin Moehring and Frank Walther
Materials 2020, 13(11), 2463; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13112463 - 28 May 2020
Cited by 4 | Viewed by 1970
Abstract
Forming technology and in particular cold forward rod extrusion is one of the key manufacturing technologies with regard to the production of shafts. The selection of process parameters determines the global and local material properties. This particularly implies forming-induced initial damage in representation [...] Read more.
Forming technology and in particular cold forward rod extrusion is one of the key manufacturing technologies with regard to the production of shafts. The selection of process parameters determines the global and local material properties. This particularly implies forming-induced initial damage in representation of pores. On this background, this study aims on describing the influence of these pores in the performance of the material 16MnCrS5 (DIN 1.7139, AISI/SAE 5115) under a torsional load path in the low cycle fatigue regime, which is highly relevant for shafts under operation conditions. For this purpose, the method of cyclic forward-reverse torsional testing was applied. Additionally, intermittent testing method and the characterization of the state of crack growth using selective electron microscopy analysis of the surface were combined. A first attempt was made to describe the influence of forming-induced initial damage on the fatigue performance and the crack growth mechanisms. The correlation of fatigue performance and initial damage was contiguous in the sense that the initial damage corresponds with a decrease of material performance. It was concluded that the focus of further investigations must be on small crack growth and the related material changes to identify the role of initial damage under cyclic loads. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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16 pages, 5258 KiB  
Article
Effect of Ultrasonic Surface Impact on the Fatigue Properties of Ti3Zr2Sn3Mo25Nb
by Zhangjianing Cheng, Xiaojian Cao, Xiaoli Xu, Qiangru Shen, Tianchong Yu and Jiang Jin
Materials 2020, 13(9), 2107; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13092107 - 02 May 2020
Cited by 5 | Viewed by 2062
Abstract
The effect of nano grain surface layer generated by ultrasonic impact on the fatigue behaviors of a titanium alloy Ti3Zr2Sn3Mo25Nb (TLM) was investigated. Three vibration strike-numbers of 24,000 times, 36,000 times and 48,000 times per unit are chosen to treat the surface of [...] Read more.
The effect of nano grain surface layer generated by ultrasonic impact on the fatigue behaviors of a titanium alloy Ti3Zr2Sn3Mo25Nb (TLM) was investigated. Three vibration strike-numbers of 24,000 times, 36,000 times and 48,000 times per unit are chosen to treat the surface of TLM specimens. Nanocrystals with an average size of 30 nm are generated. The dislocation motion plays an important role in the transformation of nanograins. Ultrasonic surface impact improves the mechanical properties of TLM, such as hardness, surface residual stress, tensile strength and fatigue strength. More vibration strike numbers will cause a higher enhancement. With a vibration strike number of 48,000 times per square millimeter the rotating-bending fatigue strength of TLM at 107 cycles is improved by 23.7%. All the fatigue cracks initiate from the surface of untreated specimens, while inner cracks appear after the fatigue life of 106 cycles with the ultrasonic surface impact. The crystal slip in the crack initiation zone is the main way of growth for microcracks. Crack cores are usually formed at the junction of crystals. The stress intensity factor of TLM titanium alloy is approximately 7.0 MPa·m1/2. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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12 pages, 5217 KiB  
Article
Analysis of Selected Properties of Welded Joints of the HSLA Steels
by Ivan Miletić, Andreja Ilić, Ružica R. Nikolić, Robert Ulewicz, Lozica Ivanović and Norbert Sczygiol
Materials 2020, 13(6), 1301; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13061301 - 13 Mar 2020
Cited by 30 | Viewed by 2619
Abstract
This paper presents research of the impact toughness and hardness distribution in specific zones of a ‘single V’butt multiple-pass welded joints of the high-strength low-alloyed steels. Obtained values of the impact toughness are analyzed in correlation with a microstructure in specific zones of [...] Read more.
This paper presents research of the impact toughness and hardness distribution in specific zones of a ‘single V’butt multiple-pass welded joints of the high-strength low-alloyed steels. Obtained values of the impact toughness are analyzed in correlation with a microstructure in specific zones of the welded joint, together with the micro hardness distribution found in the related zones. Based on the carried out analysis and results obtained in experiments, the applied technology of welding was evaluated. The original conclusions on influence of the selected welding procedure manual metal arc (MMA) for the root passes and metal active gas (MAG) for the filling and covering passes) on impact toughness of the high-strength low-alloyed steels are drawn. The paper also presents discussion on the valid standards and recommendations related to welding of those steels, from the aspect of applications in design of steel welded constructions. Full article
(This article belongs to the Special Issue Manufacturing and Fatigue Properties of Materials)
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