Special Issue "Deformation Behavior of the Alloys under Simple and Combined Loading Conditions at Various Deformation Rate"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (31 May 2018)

Special Issue Editors

Guest Editor
Prof. Takeshi Iwamoto

Academy of Science and Technology, Hiroshima University, 1-4-1 Kagamiyama, Hiroshima, Japan
Website | E-Mail
Interests: solid mechanics; impact engineering; martensitic transformation; TRIP steel; Fe-based shape memory alloy
Guest Editor
Prof. Tao Suo

School of Aeronautics, Northwestern Polytechnical University, Xi'an, China
Website | E-Mail
Interests: experimental method under extreme conditions; dynamic behavior of materials and structures

Special Issue Information

Dear Colleagues,

Clarifying the mechanical behavior of alloys is quite important to evaluate their performance, such as strength, ductility, toughness, workability, formability, etc. Actually, alloys undergo, not only simple loading, such as tension, compression, and torsion, but also quite complicated loading conditions via combinations of simple loading with proportional and non-proportional histories. Additionally, products with high performance at high-speed deformation, such as high-energy absorption, including a fracture characteristic, are quite useful to avoid the fatal accidents of transportation equipment. In both cases, strain rate sensitivity in the inelastic deformation of alloys holds the key, and it is important to clarify dynamic or impact effects of the phenomena, related to the rate sensitivity of the materials. In the Special Issue, a broad range of research works related to deformation behavior of alloys are invited, as well as interdisciplinary works concerning these topics. In addition, fundamental research works on testing methods and computational simulations are included.

This Special Issue will be composed of articles reporting on new and progressive research results, as well as reviews of particular classes of fundamental deformation behaviors of alloys and their applications. Manuscripts will be welcomed from both fundamental scientific researchers and authors belonging to industrial companies involved in the field.

Prof. Takeshi Iwamoto
Prof. Tao Suo
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. 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 1200 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

  • Simple and combined loading conditions
  • Proportional and non-proportional loading
  • Dynamic and impact deformation behavior
  • Rate sensitivity
  • Mechanical properties
  • Computational and experimental method

Published Papers (6 papers)

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Research

Open AccessArticle Influence of Stress State on the Mechanical Impact and Deformation Behaviors of Aluminum Alloys
Metals 2018, 8(7), 520; https://doi.org/10.3390/met8070520
Received: 31 May 2018 / Revised: 1 July 2018 / Accepted: 2 July 2018 / Published: 5 July 2018
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Abstract
Under impact loading conditions, the stress state derived from the contact between the projectile and the target, as well as from the subsequent mechanical waves, is a variable of great interest. The geometry of the projectile plays a dertermining role in the resulting
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Under impact loading conditions, the stress state derived from the contact between the projectile and the target, as well as from the subsequent mechanical waves, is a variable of great interest. The geometry of the projectile plays a dertermining role in the resulting stress state in the targeted structure. In this regard, different stress states lead to different failure modes. In this work, we analyze the influence of the stress state on the deformation and failure behaviors of three aluminum alloys that are commonly used in the aeronautical, naval, and automotive industries. To this purpose, tension-torsion tests are performed covering a wide range of stress triaxialities and Lode parameters. Secondly, the observations from these static tests are compared to failure mode of the same materials at high impact velocities tests with the aim of analysing the role of stress state and strain rate in the mechanical response of the aluminum plates. Experimental impacts are conducted with different projectile geometries to allow for the analysis of stress states influence. In addition, these experiments are simulated by using finite element models to evaluate the predictive capability of three failure criteria: critical plastic deformation, Johnson-Cook, and Bai-Wierzbicki. Full article
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Open AccessArticle Enhancement of Strength and Hot Workability of AZX312 Magnesium Alloy by Disintegrated Melt Deposition (DMD) Processing in Contrast to Permanent Mold Casting
Metals 2018, 8(6), 437; https://doi.org/10.3390/met8060437
Received: 12 May 2018 / Revised: 5 June 2018 / Accepted: 7 June 2018 / Published: 8 June 2018
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Abstract
AZX312 (AZ31-2Ca) magnesium alloy, with starting conditions of as-cast (AC), cast-homogenized (CH), and disintegrated melt deposition (DMD), is examined in terms of its compressive strength and hot working behavior to establish the relative merits and limitations of these processing routes. Processing maps are
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AZX312 (AZ31-2Ca) magnesium alloy, with starting conditions of as-cast (AC), cast-homogenized (CH), and disintegrated melt deposition (DMD), is examined in terms of its compressive strength and hot working behavior to establish the relative merits and limitations of these processing routes. Processing maps are developed in the temperature range of 300–500 °C and strain rate range of 0.0003–10 s−1, and mechanisms of hot deformation are established based on microstructures, tensile ductility, and activation parameters. The alloy in AC and CH conditions has a large grain size with intermetallic phases at the grain boundaries and in the matrix. In DMD processed alloy, the grain size is very small and the phases are refined and distributed uniformly. The compressive strength is significantly improved by DMD processing, which is attributed to the grain refinement. The processing maps for AC and CH conditions are similar, exhibiting only a single workability domain, while the DMD processed alloy exhibited three domains that enhanced workability. The additional workability domain at higher strain rates is an advantage in designing forming processes that facilitates faster production, while the fine grain size produced by a finishing operation in the lower temperature domain will improve the mechanical properties of the product. Full article
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Open AccessArticle A New Experimental and Numerical Framework for Determining of Revised J-C Failure Parameters
Metals 2018, 8(6), 396; https://doi.org/10.3390/met8060396
Received: 23 April 2018 / Revised: 15 May 2018 / Accepted: 27 May 2018 / Published: 30 May 2018
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Abstract
Since damage evolutions of materials play important roles in simulations, such as ballistic impacts and collisions, a new experimental and numerical method is established to determine the revised Johnson–Cook (JC) failure parameters of a 2618 aluminum alloy and a Ti-6Al-4V titanium alloy. Not
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Since damage evolutions of materials play important roles in simulations, such as ballistic impacts and collisions, a new experimental and numerical method is established to determine the revised Johnson–Cook (JC) failure parameters of a 2618 aluminum alloy and a Ti-6Al-4V titanium alloy. Not only the strain distributions, but also the stress triaxialities of designed specimens with different notches, are analyzed and revised using the finite element (FE) model. Results show that the largest strain concentrated on the surface of the circumferential area where the initial damage happened, which coincided with the practical damage evolution in the FE model. The complete damage strain, which denoted the largest strain before fracture calculated by the picture, is put forward to replace the traditional failure strain. Consequently, the digital image correlation (DIC) method and the micro speckle are carried out to measure the complete strain from the circumferential area. In addition, the relationships between the complete damage strain, the revised stress triaxiality, the strain rate and the temperature are established by conducting the quasi-static and dynamic experiments under different temperatures. Finally, the simulations for the ballistic impact tests are conducted to validate the accuracy of the parameters of the revised JC damage model. Full article
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Open AccessArticle Scaling Law in Laser-Induced Shock Effects of NiTi Shape Memory Alloy
Metals 2018, 8(3), 174; https://doi.org/10.3390/met8030174
Received: 29 January 2018 / Revised: 3 March 2018 / Accepted: 6 March 2018 / Published: 10 March 2018
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Abstract
The shock effects in laser shock processing of NiTi shape memory alloy were studied by dimensional analysis and finite element simulation. The essential dimensionless parameters controlling the residual stress distribution and plastically affected depth were found to be dimensionless pressure duration and peak
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The shock effects in laser shock processing of NiTi shape memory alloy were studied by dimensional analysis and finite element simulation. The essential dimensionless parameters controlling the residual stress distribution and plastically affected depth were found to be dimensionless pressure duration and peak pressure. By adopting the constitutive model considering the martensitic transformation and plasticity of deformation induced martensite, the influence of dimensionless parameters on the shock effects of shape memory alloy was studied numerically. The numerical results reveal the scaling law of shock effects on those dimensionless parameters quantitatively and the relationship between the plastically affected depth and peak pressure was validated with experimental results. A window of the optimal processing parameters could be obtained based on this study. Full article
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Open AccessArticle An Investigation on the Adiabatic Shear Bands in Depleted U-0.75 wt % Ti Alloy under Dynamic Loading
Metals 2018, 8(2), 145; https://doi.org/10.3390/met8020145
Received: 10 January 2018 / Revised: 1 February 2018 / Accepted: 14 February 2018 / Published: 22 February 2018
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Abstract
Adiabatic shear bands in uranium alloy projectiles/penetrators, during penetration, allow them to “self-sharpen,” a process that is absent in most tungsten alloy projectiles/penetrators. U-0.75 wt % Ti alloy samples have been accelerated to impact steel targets, and the distribution of adiabatic shear bands
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Adiabatic shear bands in uranium alloy projectiles/penetrators, during penetration, allow them to “self-sharpen,” a process that is absent in most tungsten alloy projectiles/penetrators. U-0.75 wt % Ti alloy samples have been accelerated to impact steel targets, and the distribution of adiabatic shear bands in residual samples has been studied in detail to understand the effect of self-sharpening on penetration. In our study, self-sharpening was evidenced by the distribution of the shear bands in the recovered sample. The shear bands formed during impact were observed to change direction when they crossed grain boundaries, which indicated that the grain boundaries had an influence on the adiabatic shear bands of U-0.75 wt % Ti. Micro-hardness test results showed that the Vickers micro-hardness in the adiabatic shear zone was 18% lower than that in the matrix. In the split-Hopkinson pressure bar (SHPB) experiment, a strain rate of around 2891 s−1 was the threshold strain rate that triggered the formation of adiabatic shear bands in the U-0.75 wt % Ti alloy. Full article
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Open AccessArticle Strain Rate Effect on Tensile Behavior for a High Specific Strength Steel: From Quasi-Static to Intermediate Strain Rates
Metals 2018, 8(1), 11; https://doi.org/10.3390/met8010011
Received: 6 December 2017 / Revised: 26 December 2017 / Accepted: 27 December 2017 / Published: 29 December 2017
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Abstract
The strain rate effect on the tensile behaviors of a high specific strength steel (HSSS) with dual-phase microstructure has been investigated. The yield strength, the ultimate strength and the tensile toughness were all observed to increase with increasing strain rates at the range
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The strain rate effect on the tensile behaviors of a high specific strength steel (HSSS) with dual-phase microstructure has been investigated. The yield strength, the ultimate strength and the tensile toughness were all observed to increase with increasing strain rates at the range of 0.0006 to 56/s, rendering this HSSS as an excellent candidate for an energy absorber in the automobile industry, since vehicle crushing often happens at intermediate strain rates. Back stress hardening has been found to play an important role for this HSSS due to load transfer and strain partitioning between two phases, and a higher strain rate could cause even higher strain partitioning in the softer austenite grains, delaying the deformation instability. Deformation twins are observed in the austenite grains at all strain rates to facilitate the uniform tensile deformation. The B2 phase (FeAl intermetallic compound) is less deformable at higher strain rates, resulting in easier brittle fracture in B2 particles, smaller dimple size and a higher density of phase interfaces in final fracture surfaces. Thus, more energy need be consumed during the final fracture for the experiments conducted at higher strain rates, resulting in better tensile toughness. Full article
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