Author
Jun Cai
Other affiliations: Northwestern Polytechnical University
Bio: Jun Cai is an academic researcher from Xi'an University of Architecture and Technology. The author has contributed to research in topics: Materials science & Deformation (meteorology). The author has an hindex of 13, co-authored 32 publications receiving 676 citations. Previous affiliations of Jun Cai include Northwestern Polytechnical University.
Papers
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TL;DR: In this article, the effects of temperature and strain rate on deformation behaviors were represented by Zener-Holloman parameter in an exponent-type equation, and the influence of strain was incorporated in constitutive analysis by considering the effect of strain on material constants.
208 citations
TL;DR: In this article, a constitutive equation of 7050 aluminum alloy considering the compensation of the strain was proposed, and the correlation coefficient and the average absolute relative error (AARE) were introduced to verify the validity of the constitutive equations.
92 citations
TL;DR: In this paper, a modified Johnson-Cook constitutive equation of Ti-6Al-4V alloy is proposed based on hot compression tests performed in the temperature range of 1073-1323 K and strain rate 0.001-1−s−1.
Abstract: A modified Johnson-Cook constitutive equation of Ti-6Al-4V alloy is proposed based on hot compression tests performed in the temperature range of 1073-1323 K and strain rate 0.001-1 s−1. The experimental stress-strain data were employed to develop the modified Johnson-Cook constitutive equation of different phase regimes (α + β and β phase). The predicted flow stresses using the developed equation were compared with experimental data. Correlation coefficient (R) and average absolute relative error (AARE) were introduced to verify the validity of the constitutive equation. The values of R and AARE for α + β phase were 0.990 and 7.81%, respectively. And in β phase region, the values of R and AARE were 0.985 and 10.36%, respectively. Meanwhile, the accuracy, the number of material constants involved, and the computational time required of the constitutive equation were evaluated by comparing with a strain-compensated Arrhenius-type constitutive equation. The results indicate that accuracy of modified Johnson-Cook constitutive equation is higher than that of compensated Arrhenius-type model at α + β phase, while lower at single β phase region. Meanwhile, the time required for evaluating the material constants of modified Johnson-Cook constitutive equation is much shorter than that of the strain-compensated Arrhenius type ones.
65 citations
TL;DR: In this article, the suitability levels of these two models were evaluated by comparing both the correlation coefficient R and the average absolute relative error (AARE), and the number of material constants involved in the two models was also compared.
53 citations
TL;DR: In this article, the micro mechanical behavior of quenched Ti-6Al-4V alloy was investigated in a wide range of maximum loads: 200, 300, 500, 700, 1000, 1500, 2000, 3000, 3500 and 4900mN, and loading speeds: 10, 40 and 103mN/s.
53 citations
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TL;DR: A physically founded constitutive model based on the evolution of immobile dislocation density and excess vacancy concentration is developed in this article, which is capable of describing plastic flow of the alloy in a wide range of temperature and strain rates by including the dominant deformation mechanisms like dislocation pile-up, dislocation glide, thermally activated dislocation climb, globularization etc.
154 citations
30 May 2012-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, isothermal hot compression tests were conducted at the deformation temperatures varying from 350 to 500 ÂC and strain rates ranging from 0.005 to 0.5 Â s−1.
Abstract: In order to study the high-temperature flow stress of commercial purity aluminum (AA1070), isothermal hot compression tests were conducted at the deformation temperatures varying from 350 to 500 °C and strain rates ranging from 0.005 to 0.5 s−1. The results showed that the flow stress of AA1070 was evidently affected by both the deformation temperature and strain rate. The influence of strain was also incorporated in the constitutive equation by considering the effects of strain on material constants which are consist of β, α, n, A and activation energy Q. The predicted flow stress curves using the proposed constitutive equations well agree with the experimental results of the flow stress for AA1070.
141 citations
TL;DR: In this paper, the authors used four constitutive models, namely, Johnson-Cook, Fields-Backofen (FB), Khan-Huang-Liang (KHL), and Mechanical Threshold Stress (MTS), to predict the flow behavior of Ti-6Al-4V alloy sheet.
130 citations
TL;DR: In this paper, a review of the studies of FSP in the modification of the cast structure, superplastic deformation behavior, preparation of fine-grained Mg alloys and Mg-based surface composites, and additive manufacturing is presented.
Abstract: Magnesium (Mg) alloys have been extensively used in various fields, such as aerospace, automobile, electronics, and biomedical industries, due to their high specific strength and stiffness, excellent vibration absorption, electromagnetic shielding effect, good machinability, and recyclability. Friction stir processing (FSP) is a severe plastic deformation technique, based on the principle of friction stir welding. In addition to introducing the basic principle and advantages of FSP, this paper reviews the studies of FSP in the modification of the cast structure, superplastic deformation behavior, preparation of fine-grained Mg alloys and Mg-based surface composites, and additive manufacturing. FSP not only refines, homogenizes, and densifies the microstructure, but also eliminates the cast microstructure defects, breaks up the brittle and network-like phases, and prepares fine-grained, ultrafine-, and nano-grained Mg alloys. Indeed, FSP significantly improves the comprehensive mechanical properties of the alloys and achieves low-temperature and/or high strain rate superplasticity. Furthermore, FSP can produce particle- and fiber-reinforced Mg-based surface composites. As a promising additive manufacturing technique of light metals, FSP enables the additive manufacturing of Mg alloys. Finally, we prospect the future research direction and application with friction stir processed Mg alloys.
123 citations
TL;DR: In this paper, the tensile fracture behavior of the Ti-6Al-4V alloy was examined with scanning electron microscope (SEM) over the range of magnifications.
117 citations