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14 pages, 4487 KiB

Open AccessArticle

The Gradient Effect on Cyclic Behavior of 316L Stainless Steel in the Ultrasonic Bending Test

by Yongtao Hu, Sen Tang, Yongjie Liu, Lang Li, Chong Wang and Qingyuan Wang

Materials 2024, 17(7), 1657; https://doi.org/10.3390/ma17071657 - 04 Apr 2024

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Nanoindentation measurements were conducted to investigate the high-cycle response of 316L stainless steel in bending fatigue. Hardness variation owing to the gradient flexure stress amplitude for different curvatures was plotted along with the thickness and length, respectively. Scanning electron microscopy (SEM) was subsequently [...] Read more.

Nanoindentation measurements were conducted to investigate the high-cycle response of 316L stainless steel in bending fatigue. Hardness variation owing to the gradient flexure stress amplitude for different curvatures was plotted along with the thickness and length, respectively. Scanning electron microscopy (SEM) was subsequently conducted to explore the deformation characteristics in multiple layers, which had cyclic gradient stress, on the cross-section of specimens. The nanoindentation results indicated that the cyclic hardening response of 316L stainless steel is correlated with the level of stress amplitude in the high-cycle fatigue (HCF) regime. Furthermore, an analytical model was proposed to clarify the relationship between nanohardness and stress amplitude. Finally, the evolution of damage accumulation due to irreversible plastic deformation is continuous during stress reduction up to the neighboring zone at the neutral surface of the flexure beam in some individual grains. Full article

(This article belongs to the Special Issue Mechanics Behavior, Fatigue Damage, and Microstructure Evolution of Metallic Material)

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19 pages, 6707 KiB

Open AccessArticle

The Low-Cycle Fatigue Behavior, Microstructure Evolution, and Life Prediction of SS304: Influence of Temperature

by Ting Mei, Quanyi Wang, Meng Liu, Yunqing Jiang, Tongfei Zou and Yifan Cai

Materials 2023, 16(18), 6326; https://doi.org/10.3390/ma16186326 - 21 Sep 2023

Cited by 2 | Viewed by 743

Abstract

To study the fatigue failure and microstructure evolution behavior of SS304, low-cycle fatigue tests are conducted at room temperature (RT), 300 °C, and 650 °C. The results indicate that, because of the influence of the dislocation walls, carbon-containing precipitates, and deformation twins, the [...] Read more.

To study the fatigue failure and microstructure evolution behavior of SS304, low-cycle fatigue tests are conducted at room temperature (RT), 300 °C, and 650 °C. The results indicate that, because of the influence of the dislocation walls, carbon-containing precipitates, and deformation twins, the cyclic hardening behavior is presented at RT. However, different from the cyclic hardening behavior at RT, the cyclic softening behavior of SS304 can be observed due to the dynamic recovery and recrystallization containing dislocation rearrangement and annihilation at 300 °C and 650 °C. In addition, two fatigue crack initiation modes are observed. At RT, the single fatigue crack initiation mode is observed. At high temperatures, multiple crack initiation modes are presented, resulting from the degradation of material properties. Furthermore, a new fatigue life prediction model considering the temperature is conducted as a reference for industrial applications. Full article

(This article belongs to the Special Issue Mechanics Behavior, Fatigue Damage, and Microstructure Evolution of Metallic Material)

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17 pages, 6136 KiB

Open AccessArticle

Study on Microstructure Evolution Mechanism of Gradient Structure Surface of AA7075 Aluminum Alloy by Ultrasonic Surface Rolling Treatment

by Lei Fu, Xiulan Li, Li Lin, Zhengguo Wang, Yingqian Zhang, Yunrong Luo, Shisen Yan, Chao He and Qingyuan Wang

Materials 2023, 16(16), 5616; https://doi.org/10.3390/ma16165616 - 14 Aug 2023

Cited by 1 | Viewed by 822

Abstract

The materials with grain size gradient variation on the surface, which were prepared with mechanical-induced severe plastic deformation, always show high resistance to high and low cycle fatigue and frictional wear because of their good strength–ductility synergy. The ultrasonic surface rolling treatment (USRT) [...] Read more.

The materials with grain size gradient variation on the surface, which were prepared with mechanical-induced severe plastic deformation, always show high resistance to high and low cycle fatigue and frictional wear because of their good strength–ductility synergy. The ultrasonic surface rolling treatment (USRT) has the advantages of high processing efficiency, good surface quality, and large residual compressive stress introduced to the surface after treatment. The USRT was used to prepare aluminum alloy (AA7075) samples with a surface gradient structure; meanwhile, the microstructural evolution mechanism of the deformation layers on the gradient structure was studied with XRD, SEM, and TEM. The microstructure with gradient distribution of grain size and dislocation density formed on the surface of AA7075 aluminum alloy after USRT. The surface layer consists of nanocrystals with random orientation distribution, and high-density dislocation cells and subgrains formed in some grains in the subsurface layer, while the center of the material is an undeformed coarse-grained matrix. The results show that the dislocation slip dominates the grain refinement process, following the continuous cutting and refinement of dislocation cells, subgrains, and fragmentation of the second precipitates. This study systematically clarified the mechanism of grain refinement and nanocrystallization on the surface of high-strength aluminum alloys and laid a theoretical foundation for further research on mechanical behavior and surface friction and wear properties of high-strength non-ferrous materials with gradient structure. Full article

(This article belongs to the Special Issue Mechanics Behavior, Fatigue Damage, and Microstructure Evolution of Metallic Material)

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17 pages, 16280 KiB

Open AccessArticle

Microstructure-Based Multiscale Modeling of Deformation in MarBN Steel under Uniaxial Tension: Experiments and Finite Element Simulations

by Yida Zhang, Hong Zhang, Tongfei Zou, Meng Liu, Quanyi Wang, Yubing Pei, Yongjie Liu and Qingyuan Wang

Materials 2023, 16(14), 5194; https://doi.org/10.3390/ma16145194 - 24 Jul 2023

Cited by 1 | Viewed by 1059

Abstract

In the current work, a multiscale model was developed coupling a macro-model with the macromechanical physically based yield strength and a crystal plasticity model with micromechanical properties and realistic grain orientation based on the representative volume element. The simulation results show that the [...] Read more.

In the current work, a multiscale model was developed coupling a macro-model with the macromechanical physically based yield strength and a crystal plasticity model with micromechanical properties and realistic grain orientation based on the representative volume element. The simulation results show that the effect of microstructure on the macromechanical properties can be considered in the macro constitutive model due to a good consistency between experimental and computed results; whereas solid strengthening, grain boundaries, and dislocation density played a more crucial role than others. Besides coupling simulation and microstructure by EBSD, the microstructure evolution can be well explained by the micromechanical model. Strain is related to the grain orientation, leading to inhomogeneous deformation, forming the various Schmid factor and slip systems. A plastic strain occurs close to the grain boundaries and declines into the grain, resulting in higher kernel average misorientation (KAM) and geometry necessary dislocations (GNDs) in the grain boundaries. The higher the loading, the higher the local strain. Shear bands with around 45 degrees can be formed, resulting in crack initiation and tensile shear failure. This work has developed the guidance of structural integrity assessment and prediction of mechanical properties for the engineering material and components. Full article

(This article belongs to the Special Issue Mechanics Behavior, Fatigue Damage, and Microstructure Evolution of Metallic Material)

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12 pages, 12532 KiB

Open AccessArticle

Microstructures and Mechanical Properties of Al-Zn-Mg-Cu Alloys under Multi-Directional Severe Strain and Aging

by Chunhua Wei, Zhixin Lei, Sijie Du, Rongyou Chen, Yutang Yin, Chenglin Niu and Zhengbing Xu

Materials 2023, 16(12), 4441; https://doi.org/10.3390/ma16124441 - 17 Jun 2023

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Abstract

Microstructure is a significant factor that influences the mechanical properties of alloys. The effect of multiaxial forging (MAF) and subsequent aging treatment on the precipitated phases of Al-Zn-Mg-Cu alloy remains unclear. Therefore, an Al-Zn-Mg-Cu alloy was processed by means of solid solution and [...] Read more.

Microstructure is a significant factor that influences the mechanical properties of alloys. The effect of multiaxial forging (MAF) and subsequent aging treatment on the precipitated phases of Al-Zn-Mg-Cu alloy remains unclear. Therefore, an Al-Zn-Mg-Cu alloy was processed by means of solid solution and aging treatment, and MAF and aging treatment in this work, and the composition and distribution of precipitated phases were characterized in detail. The MAF results for dislocation multiplication and grain refinement were found. The high density of dislocation greatly accelerates the nucleation and growth of precipitated phases. Thus, the GP-zones almost transform into precipitated phases during subsequent aging. The MAF and aging alloy has more precipitated phases than the solid solution and aging treated alloy. The precipitates on the grain boundary are coarse and discontinuously distributed due to dislocation and grain boundary promoting the nucleation, growth and coarsening of the precipitates. The hardness, strength, ductility and microstructures of the alloy have been studied. Without compromising the ductility much, the MAF and aging alloy has higher hardness and strength, with values of 202 HV and 606 MPa, respectively, and an appreciable ductility of 16.2%. Full article

(This article belongs to the Special Issue Mechanics Behavior, Fatigue Damage, and Microstructure Evolution of Metallic Material)

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18 pages, 6570 KiB

Open AccessEditor’s ChoiceArticle

Fracture Response of X80 Pipe Girth Welds under Combined Internal Pressure and Bending Moment

by Li Zhu, Naixian Li, Bin Jia and Yu Zhang

Materials 2023, 16(9), 3588; https://doi.org/10.3390/ma16093588 - 07 May 2023

Cited by 1 | Viewed by 1426

Abstract

In order to determine the effect of defect size on the pipeline fracture performance of girth welds in oil and gas pipelines, ABAQUS was used to simulate the fracture responses of X80 pipelines with girth weld defects under internal pressure and bending moment [...] Read more.

In order to determine the effect of defect size on the pipeline fracture performance of girth welds in oil and gas pipelines, ABAQUS was used to simulate the fracture responses of X80 pipelines with girth weld defects under internal pressure and bending moment conditions based on damage mechanics. In particular, the length and depth of defects were parametrically studied; the defect depth range was 20–80% of the wall thickness, and the circumferential length range of the defects was 5–20% of the pipeline circumference. The results show that, under the combined action of internal pressure and bending moment, the defect depth was more associated with adverse effects than the circumferential length of the defect. The failure load did not linearly decrease as the size of the defect increased, but when the depth of the defect reached a certain value, the failure load suddenly decreased. Full article

(This article belongs to the Special Issue Mechanics Behavior, Fatigue Damage, and Microstructure Evolution of Metallic Material)

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25 pages, 75090 KiB

Open AccessArticle

Temperature and Strain Rate Dependence on the Tensile Mechanical Properties, Constitutive Equations, and Fracture Mechanisms of MarBN Steel

by Yunqing Jiang, Tongfei Zou, Meng Liu, Yifan Cai, Quanyi Wang, Yunru Wang, Yubing Pei, Hong Zhang, Yongjie Liu and Qingyuan Wang

Materials 2023, 16(8), 3232; https://doi.org/10.3390/ma16083232 - 19 Apr 2023

Cited by 2 | Viewed by 1401

Abstract

The effect of strain rate and temperature on the thermomechanical behavior and microstructure of MarBN steel is studied with the strain rates of 5 × 10⁻³ and 5 × 10⁻⁵ s⁻¹ from room temperature (RT) to 630 °C. At high [...] Read more.

The effect of strain rate and temperature on the thermomechanical behavior and microstructure of MarBN steel is studied with the strain rates of 5 × 10⁻³ and 5 × 10⁻⁵ s⁻¹ from room temperature (RT) to 630 °C. At high strain rates of 5 × 10⁻³ s⁻¹, the Holloman and Ludwigson equations can better predict tensile plastic properties. In contrast, under low strain rates of 5 × 10⁻⁵ s⁻¹, coupling of the Voce and Ludwigson equations appears to predict the flow relationship at RT, 430, and 630 °C. However, the deformation microstructures have the same evolution behavior under strain rates and temperatures. Geometrically necessary dislocations appear along the grain boundaries and increase the dislocation density, which results in the formation of the low-angle grain boundaries and a decrease in the number of twinning. The strengthening sources of MarBN steel include grain boundary strengthening, dislocation interactions, and multiplication. The fitted R² values of these models (JC, KHL, PB, VA, ZA) to plastic flow stress at 5 × 10⁻⁵ s⁻¹ are greater than 5 × 10⁻³ s⁻¹ for MarBN steel. Due to the flexibility and minimum fitting parameters, the phenomenological models of JC (RT and 430 °C) and KHL (630 °C) give the best prediction accuracy under both strain rates. Full article

(This article belongs to the Special Issue Mechanics Behavior, Fatigue Damage, and Microstructure Evolution of Metallic Material)

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Review

Jump to: Research

20 pages, 1313 KiB

Open AccessReview

A Review of Research Progress on Ti(C,N)-Based Cermet Binder by Intermetallic Compounds and High-Entropy Alloys

by Liang Wang, Jingfei Bai, Yanghe Wang and Zhengxing Men

Materials 2024, 17(3), 675; https://doi.org/10.3390/ma17030675 - 30 Jan 2024

Viewed by 562

Abstract

Ti(C,N)-based cermet is a kind of composite material composed of a metal binder phase and a Ti(C,N)-hard phase, which is widely used in the fields of cutting machining and wear-resistant parts due to its high hardness, good toughness, wear resistance, and chemical stability. [...] Read more.

Ti(C,N)-based cermet is a kind of composite material composed of a metal binder phase and a Ti(C,N)-hard phase, which is widely used in the fields of cutting machining and wear-resistant parts due to its high hardness, good toughness, wear resistance, and chemical stability. In recent years, the research on the replacement of traditional Ni, Co, and Fe binder phases by novel binder phases such as intermetallic compounds and high-entropy alloys has made remarkable progress, which significantly improves the mechanical properties, wear resistance, corrosion resistance, and high-temperature oxidation resistance of Ti(C,N)-based cermets. This paper reviews the latest research results, summarizes the mechanism of the new binder to improve the performance of metal–ceramics, and looks forward to the future research directions. Full article

(This article belongs to the Special Issue Mechanics Behavior, Fatigue Damage, and Microstructure Evolution of Metallic Material)

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