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Article
Publication date: 13 December 2023

Zhenyu Ma, Yupeng Zhang, Xuguang An, Jing Zhang, Qingquan Kong, Hui Wang, Weitang Yao and Qingyuan Wang

The purpose of this study is to investigate the effect of nano ZrC particles on the mechanical and electrochemical corrosion properties of FeCrAl alloys, providing a beneficial…

115

Abstract

Purpose

The purpose of this study is to investigate the effect of nano ZrC particles on the mechanical and electrochemical corrosion properties of FeCrAl alloys, providing a beneficial reference basis for the development of high-performance carbide reinforced FeCrAl alloys with good mechanical and corrosion properties in the future.

Design/methodology/approach

Nano ZrC reinforced FeCrAl alloys were prepared by mechanical alloying and spark plasma sintering. Phases composition, tensile fractography, corrosion morphology and chemical composition of nano ZrC reinforced FeCrAl alloys were analyzed by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. Microhardness and tensile properties of nano ZrC reinforced FeCrAl alloys were investigated by mechanical testing machine and Vickers hardness tester. Electrochemical corrosion properties of nano ZrC reinforced FeCrAl alloys were investigated by electrochemical workstation in 3.5 wt.% NaCl solution.

Findings

The results showed that addition of nano ZrC can effectively improve the mechanical and corrosion properties. However, excessive nano ZrC could decrease the mechanical properties and reduce the corrosion resistance. In all the FeCrAl alloys, FeCrAl–0.6 wt.% ZrC alloy exhibits the optimum mechanical properties with an ultimate tensile strength, elongation and hardness of 990.7 MPa, 24.1% and 335.8 HV1, respectively, and FeCrAl–0.2 wt.% ZrC alloy has a lower corrosion potential (−0.179 V) and corrosion current density (2.099 µA/cm2) and larger pitting potential (0.497 V) than other FeCrAl–ZrC alloys, showing a better corrosion resistance.

Originality/value

Adding proper nano ZrC particles can effectively improve the mechanical and corrosion properties, while the excessive nano ZrC is harmful to the mechanical and corrosion properties of FeCrAl alloys, which provides an instruction to develop high-performance FeCrAl cladding materials.

Details

Anti-Corrosion Methods and Materials, vol. 71 no. 1
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 5 January 2022

Kai Tan, Victor Postel, Yujia Liu, Dongtong Yang, Sen Tang, Chong Wang and Qingyuan Wang

Mechanical issues related to the information and growth of small cracks are considered to play a major role in very high cycle fatigue (VHCF) for metallic materials. Further…

266

Abstract

Purpose

Mechanical issues related to the information and growth of small cracks are considered to play a major role in very high cycle fatigue (VHCF) for metallic materials. Further efforts on better understanding in early stage of a crack are beneficial to estimating and preventing catastrophic damage for a long period service.

Design/methodology/approach

Dependent on the ultrasonic loading system, a novel method of in situ photomicroscope is established to study the crack behaviors in VHCF regime.

Findings

This in situ photomicroscope method provides advantages in combination with fatigue damage monitoring at high magnification, a large number of cycles, and efficiency. Visional investigation with attached image proceeding code proves that the method has high resolution on both size and time, which permits reliable accuracy on small crack growth rate. It is observed that the crack propagation trends slower in the overall small crack stage down to the level of 10–11 m/cycle. Strain analysis relays on a real-time recording which is applied by using digital image correlation. Infrared camera recording indicates the method is also suitable for thermodynamic study while growth of damage.

Originality/value

Benefiting from this method, it is more convenient and efficient to study the short crack propagation in VHCF regime.

Details

International Journal of Structural Integrity, vol. 13 no. 2
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 21 July 2022

Yajun Dai, Chang Liu, Min Zhan, Xiangyu Wang, Chao He and Qingyuan Wang

The investigations provide a basis for the optimization of the alloy 6061-T6 friction stir welding (FSW) process to improve the mechanical properties of welded joints.

135

Abstract

Purpose

The investigations provide a basis for the optimization of the alloy 6061-T6 friction stir welding (FSW) process to improve the mechanical properties of welded joints.

Design/methodology/approach

The local deformation of the FSW joint in tension and fatigue test were experimentally investigated by digital image correlation (DIC) technique.

Findings

The local stress-strain behaviors of the sub-regions show that the plastic strain always concentrated at the heat affected zone (HAZ) on the advancing side both in tension and high cycle fatigue and eventually leads to the final fracture. The evolution of the plastic strain at very low stress is extremely slow and accounts for most of the total fatigue life. However, the local deformation exhibits a sudden increase just before the fatigue failure.

Originality/value

Based on the experimental data, the result indicates that the HAZ is the weakest zone across the weld and the strain localization in high cycle fatigue is very harmful and unpredictable for the FSW joints.

Details

International Journal of Structural Integrity, vol. 13 no. 5
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 12 September 2023

Min Zhan, Yajun Dai, Chang Liu, Xiangyu Wang, Lang Li, Yongjie Liu, Chao He and Qingyuan Wang

The purpose of this paper is to determine (1) the relationship between microstructure and fatigue cracking behavior and (2) effect of rolling on the process of crack initiation…

124

Abstract

Purpose

The purpose of this paper is to determine (1) the relationship between microstructure and fatigue cracking behavior and (2) effect of rolling on the process of crack initiation and propagation in FeCrAl alloys.

Design/methodology/approach

The qualitative and quantitative fracture studies were performed using scanning electron microscopy and the non-contact optical measurement system (IFMG5).

Findings

The results show that the formation of facets, rough facets and parallel stripes in the crack initiation and early crack propagation zones are closely related to the sensitivity of crack behavior to the microstructure of the material. Besides, the rolling process has a significant influence on the small crack initiation and propagation behavior. Quantitative analysis demonstrates that the size of the stress intensity factor and plastic zone size in the rough zone is associated with the rolling process.

Originality/value

The findings of this study have the potential to enhance the understanding of the microstructural crack formation mechanisms in FeCrAl alloys and shed light on the impact of rolling on the long-term and ultra-long fatigue behavior of these alloys. This new knowledge is vital for improving manufacturing processes and ensuring the safety and reliability of FeCrAl alloys used in nuclear industry applications.

Details

International Journal of Structural Integrity, vol. 14 no. 5
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 6 March 2024

Qiuchen Zhao, Xue Li, Junchao Hu, Yuehui Jiang, Kun Yang and Qingyuan Wang

The purpose of this paper is to determine the ultra-high cycle fatigue behavior and ultra-slow crack propagation behavior of selective laser melting (SLM) AlSi7Mg alloy under…

143

Abstract

Purpose

The purpose of this paper is to determine the ultra-high cycle fatigue behavior and ultra-slow crack propagation behavior of selective laser melting (SLM) AlSi7Mg alloy under as-built conditions.

Design/methodology/approach

Constant amplitude and two-step variable amplitude fatigue tests were carried out using ultrasonic fatigue equipment. The fracture surface of the failure specimen was quantitatively analyzed by scanning electron microscope (SEM).

Findings

The results show that the competition of surface and interior crack initiation modes leads to a duplex S–N curve. Both manufacturing defects (such as the lack of fusion) and inclusions can act as initially fatal fatigue microcracks, and the fatigue sensitivity level decreases with the location, size and type of the maximum defects.

Originality/value

The research results play a certain role in understanding the ultra-high cycle fatigue behavior of additive manufacturing aluminum alloys. It can provide reference for improving the process parameters of SLM technology.

Details

International Journal of Structural Integrity, vol. 15 no. 2
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 31 January 2020

Hui Li, Lei Fu, Li Lin, Yu Chen, YunRong Luo, XiuLan Li, WenLing Xie and Qingyuan Wang

In summary, it can be found that the current research on the simulation of natural atmospheric dry–wet alternating accelerated corrosion mainly focused on the study of…

225

Abstract

Purpose

In summary, it can be found that the current research on the simulation of natural atmospheric dry–wet alternating accelerated corrosion mainly focused on the study of electrochemical corrosion process and the study of corrosion rate; the micro-pre-corrosion mechanism of materials in this environment, especially for materials. The specific effects of fatigue and fracture performance still lack detailed research. Accordingly, this study aims to more realistically simulate the effect of natural atmospheric corrosion environment on the corrosion resistance and fatigue performance of aircraft skin.

Design/methodology/approach

In this study, the uniaxial strain control method was used to test the fatigue performance of pre-corrosion samples under simulated natural atmospheric corrosion using MTS809 tensile-torque composite fatigue machine. Scanning electron microscopy, X-ray energy spectrum analysis, atomic force microscopy and X-ray diffraction analysis were used. Fatigue fracture, corrosion morphology and corrosion products were analyzed.

Findings

The results show that the deep corrosion pit caused by pre-corrosion environment leads to multi-source initiation of crack; the fatigue life of pre-corroded sample decreases by about one-half, chloride ion invades the material and promotes intergranular corrosion; life prediction results show that the natural atmospheric corrosive environment mainly affects the plastic term in the Manson–Coffin formula resulting in a decrease in fatigue life.

Originality/value

Innovative experimental schemes and materials are used and the test temperature and relative humidity are strictly controlled. The corrosion failure mechanism of 2A70-T6 aluminum alloy under alternating wet and dry accelerated corrosion environment and its influence on fatigue behavior were obtained.

Details

Anti-Corrosion Methods and Materials, vol. 67 no. 2
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 2 September 2021

Lei Fu, Hui Li, Li Lin, Qingyuan Wang, Qi Fan, Xinjie Huang, XiuLan Li, Sheng Lai and Lifei Chen

Most supersonic aircraft were manufactured using 2A70 aluminum alloy. The purpose of this paper is to study the corrosion mechanism and fatigue behavior of an aircraft in a…

350

Abstract

Purpose

Most supersonic aircraft were manufactured using 2A70 aluminum alloy. The purpose of this paper is to study the corrosion mechanism and fatigue behavior of an aircraft in a semi-industrial atmospheric corrosive environment, alternating effects of corrosion and fatigue were used to simulate the aircraft’s ground parking corrosion and air flight fatigue.

Design/methodology/approach

For this purpose, the aluminum alloy samples were subjected to pre-corrosion and alternating corrosion-fatigue experiments. The failure mechanisms of corrosion and corrosion fatigue were analyzed using microscopic characterization methods of electrochemical testing, X-ray diffraction and scanning electron microscopy. Miner’s linear cumulative damage rule was used to predict the fatigue life of aluminum alloy and to obtain its safe fatigue life.

Findings

The results showed that the corrosion damage caused by the corrosive environment was gradually connected by pitting pits to form denudation pits along grain boundaries. The deep excavation of chloride ions and the presence of intergranular copper-rich phases result in severe intergranular corrosion morphology. During cyclic loading, alternating hardening and softening occurred. The stress concentration caused by surface pitting pits and denudation pits initiated fatigue cracks at intergranular corrosion products. At the same time, the initiation of multiple fatigue crack sources was caused by the corrosion environment and the morphology of the transient fracture zone was also changed, but the crack propagation rate was not basically affected. The polarization curve and impedance analysis results showed that the corrosion rate increases first, decreases and then increases. Fatigue failure behavior was directly related to micro characteristics such as corrosion pits and microcracks.

Originality/value

In this research, alternating effects of corrosion and fatigue were used to simulate the aircraft’s ground parking corrosion and air flight fatigue. To study the corrosion mechanism and fatigue behavior of an aircraft in a semi-industrial atmospheric corrosive environment, the Miner’s linear cumulative damage rule was used to predict the fatigue life of aluminum alloy and to obtain its safe fatigue life.

Details

Anti-Corrosion Methods and Materials, vol. 68 no. 5
Type: Research Article
ISSN: 0003-5599

Keywords

Available. Content available
Article
Publication date: 8 April 2024

José A.F.O. Correia and Shun-Peng Zhu

266

Abstract

Details

International Journal of Structural Integrity, vol. 15 no. 2
Type: Research Article
ISSN: 1757-9864

Available. Open Access. Open Access
Article
Publication date: 5 September 2016

Qingyuan Wu, Changchen Zhan, Fu Lee Wang, Siyang Wang and Zeping Tang

The quick growth of web-based and mobile e-learning applications such as massive open online courses have created a large volume of online learning resources. Confronting such a…

3606

Abstract

Purpose

The quick growth of web-based and mobile e-learning applications such as massive open online courses have created a large volume of online learning resources. Confronting such a large amount of learning data, it is important to develop effective clustering approaches for user group modeling and intelligent tutoring. The paper aims to discuss these issues.

Design/methodology/approach

In this paper, a minimum spanning tree based approach is proposed for clustering of online learning resources. The novel clustering approach has two main stages, namely, elimination stage and construction stage. During the elimination stage, the Euclidean distance is adopted as a metrics formula to measure density of learning resources. Resources with quite low densities are identified as outliers and therefore removed. During the construction stage, a minimum spanning tree is built by initializing the centroids according to the degree of freedom of the resources. Online learning resources are subsequently partitioned into clusters by exploiting the structure of minimum spanning tree.

Findings

Conventional clustering algorithms have a number of shortcomings such that they cannot handle online learning resources effectively. On the one hand, extant partitional clustering methods use a randomly assigned centroid for each cluster, which usually cause the problem of ineffective clustering results. On the other hand, classical density-based clustering methods are very computationally expensive and time-consuming. Experimental results indicate that the algorithm proposed outperforms the traditional clustering algorithms for online learning resources.

Originality/value

The effectiveness of the proposed algorithms has been validated by using several data sets. Moreover, the proposed clustering algorithm has great potential in e-learning applications. It has been demonstrated how the novel technique can be integrated in various e-learning systems. For example, the clustering technique can classify learners into groups so that homogeneous grouping can improve the effectiveness of learning. Moreover, clustering of online learning resources is valuable to decision making in terms of tutorial strategies and instructional design for intelligent tutoring. Lastly, a number of directions for future research have been identified in the study.

Details

Asian Association of Open Universities Journal, vol. 11 no. 2
Type: Research Article
ISSN: 1858-3431

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Article
Publication date: 8 August 2024

QingYuan Zhou, Yangting Sun, Xiangyu Wang, Xin Tan, Yiming Jiang and Jin Li

This study aims to assess the pitting resistance of austenitic stainless steel welded joints fusion zone (FZ) with high density of inclusions before and after surface treatment…

70

Abstract

Purpose

This study aims to assess the pitting resistance of austenitic stainless steel welded joints fusion zone (FZ) with high density of inclusions before and after surface treatment, including potentiostatic pulse technique (PPT) and pickling.

Design/methodology/approach

The potentiodynamic polarization tests and critical pitting temperature tests were carried out for estimating pitting resistance. The PPT and pickling were performed as surface treatment. Scanning electron microscope (SEM) and energy dispersive spectrometer were used for characterize the microstructure and elemental distribution. Electron back-scattered diffraction (EBSD) was used to assess the portion of phases and morphology of grains.

Findings

The weld metal exhibits a higher degree of alloying compared to the base metal, and it contains d-phase and sulfur-containing inclusions. Sulfur-containing inclusions serve as initiation sites for pitting, and they diminish the pitting resistance of weld metal. Both PPT and pickling can remove sulfur-containing inclusions, but PPT causes localized dissolution of the weld metal matrix around the inclusions, while pickling does not. Because of the high density of inclusions, certain pits initiated by PPT are significantly deeper, which makes the formation of stable pitting easier. Because of the high density of inclusions, certain pits initiated by the PPT are deeper. This characteristic facilitates the progression of these initial defects into fully developed, stable pits.

Originality/value

Analysis of pitting initiation in shielded metal arc welding FZ with PPT and ex situ SEM tracking observation. Explanation of why the PPT surface treatment is not able to enhance the pitting resistance of stainless steel with a high inclusion density.

Details

Anti-Corrosion Methods and Materials, vol. 71 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

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