Constitutive flow behavior and hot workability of powder metallurgy processed 20 vol.%SiCP/2024Al composite
15 Nov 2010-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing (Elsevier)-Vol. 527, Iss: 29, pp 7865-7872
TL;DR: In this article, the authors investigated the constitutive flow behavior and hot workability of powder metallurgy processed 20 vol.%SiC(P)/2024Al composite using hot compression tests.
Abstract: Constitutive flow behavior and hot workability of the powder metallurgy processed 20 vol.%SiC(P)/2024Al composite were investigated using hot compression tests. The modified Arrhenius-type constitutive equations were presented with the values of material constants in consideration as a function of strain. Dynamic material model (DMM) and modified DMM were used to construct the power dissipation efficiency maps, and Ziegler's instability criterion and Gegel's stability criterion were used to build instability maps. The presence of finer SiC(P) and more boundaries resulting from smaller 2024Al powders shifted the dynamic recrystallization domain of the 2024Al matrix to higher strain rate and lower temperature ranges and decreased the peak value of power dissipation efficiency. Large instable regions were found in the form of flow localization and cavitations located at the matrix/SiC(P) interfaces and within the SiC(P) clusters. By comparison, the Gegel's stability criterion was more sensitive to the instability zones than the Ziegler's instability criterion for this material. (c) 2010 Elsevier B.V. All rights reserved.
Citations
More filters
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 investigated the hot deformation behavior of fine-grained SiCp/AZ91 composite at the temperature of 543 −693 K and strain rate of 0.001 −1−s−1.
67 citations
TL;DR: In this article, a comparative study was carried out on the appropriateness of hyperbolic sine, power, and exponential descriptions of Zener-Hollomon parameter (Z) in prediction of high-temperature flow stress by consideration of the effect of strain.
Abstract: A comparative study was carried out on the appropriateness of hyperbolic sine, power, and exponential descriptions of Zener–Hollomon parameter (Z) in prediction of high-temperature flow stress by consideration of the effect of strain. It was shown that the main problem of the conventional strain compensation approach is the implementation of the constitutive equations to find the strain-dependent material constants, especially the hot deformation activation energy (Q), at constant strain values, which arises from the change in the microstructure of the material at a given strain for different deformation conditions (different Z values). Subsequently, a simplified approach for each constitutive equation, mainly by taking Q from the peak stress analysis, was proposed to solve this issue. This also resulted in significantly better prediction abilities for unseen deformation conditions and effectively simplified the required calculations.
66 citations
TL;DR: In this paper, hot deformation experiments were carried out on Al 5083-2%TiC nanocomposite samples to analyse and establish the relation between the microstructural behavior and control process parameters such as temperature, strain and strain-rate.
59 citations
15 May 2011-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the effects of strain rate and temperature on hot deformation behavior were represented by Zener-Hollomon parameter including Arrhenius term, and four material constants α, n, A and activation energy Q in the equations were calculated by compensation of strain.
Abstract: In order to find material parameters of established Zener–Hollomon constitutive equations and predict high-temperature flow stress of Al–14Cu–7Ce alloy, isothermal hot compression tests were conducted using a Gleeble 3500 thermomechanical simulator at constant stain rates of 0.001, 0.01, 0.1 and 1 s−1 and at temperatures ranging from 300 to 550 °C at intervals of 50 °C. The effects of strain rate and temperature on hot deformation behavior were represented by Zener–Hollomon parameter including Arrhenius term. Four material constants α, n, A and activation energy Q in the equations were calculated by compensation of strain. The results show that the proposed constitutive equations give a precise estimate for high temperature flow stress of Al–14Cu–7Ce alloy, which means it can be used for numerical simulation of hot deformation process and for choosing proper deformation parameter in engineering practice accurately.
54 citations
References
More filters
TL;DR: In this article, the current status of particle reinforced metal matrix composites is reviewed and the different types of reinforcement being used, together with the alternative processing methods, are discussed, and different factors have to be taken into consideration to produce a high quality billet.
Abstract: Particle reinforced metal matrix composites are now being produced commerically, and in this paper the current status of these materials is reviewed. The different types of reinforcement being used, together with the alternative processing methods, are discussed. Depending on the initial processing method, different factors have to be taken into consideration to produce a high quality billet. With powder metallurgy processing, the composition of the matrix and the type of reinforcement are independent of one another. However, in molten metal processing they are intimately linked in terms of the different reactivities which occur between reinforcement and matrix in the molten state. The factors controlling the distribution of reinforcement are also dependent on the initial processing method. Secondary fabrication methods, such as extrusion and rolling, are essential in processing composites produced by powder metallurgy, since they are required to consolidate the composite fully. Other methods, suc...
1,961 citations
Book•
01 Jan 1993TL;DR: In this article, the Eshelby approach is used to model composites and a program for calculating the S-tensors of a composite model is presented, along with a list of programs for an Eshelbys calculation.
Abstract: Preface 1. General introduction 2. Basic composite models 3. The Eshelby approach to modelling composites 4. Plastic deformation 5. Thermal effects and high temperature behaviour 6. The interfacial region 7. Fracture processes and failure mechanisms 8. Transport properties and environmental performance 9. Fabrication processes 10. Development of matrix microstructure 11. Testing and characterisation techniques 12. Applications Appendix 1. Nomenclature Appendix 2. Matrices and reinforcements - selected thermophysical properties Appendix 3. The basic Eshelby S-tensors Appendix 4. Listing of a program for an Eshelby calculation.
1,826 citations
"Constitutive flow behavior and hot ..." refers background in this paper
...[1] T....
[...]
...Aluminum matrix composites (AMCs) reinforced with SiCP are ecognized as important advanced structuralmaterials due to their esirable properties, including high specific stiffness, high speific strength, high-temperature resistance and improved wear esistance [1–3]....
[...]
TL;DR: In this article, a new method of modeling material behavior which accounts for the dynamic metallurgical processes occurring during hot deformation is presented, which considers the workpiece as a dissipator of power in the total processing system and evaluates the dissipated power co-contentJ = ∫o σ e ⋅dσ from the constitutive equation relating the strain rate (e) to the flow stress (σ).
Abstract: A new method of modeling material behavior which accounts for the dynamic metallurgical processes occurring during hot deformation is presented. The approach in this method is to consider the workpiece as a dissipator of power in the total processing system and to evaluate the dissipated power co-contentJ = ∫o σ e ⋅dσ from the constitutive equation relating the strain rate (e) to the flow stress (σ). The optimum processing conditions of temperature and strain rate are those corresponding to the maximum or peak inJ. It is shown thatJ is related to the strain-rate sensitivity (m) of the material and reaches a maximum value(J max) whenm = 1. The efficiency of the power dissipation(J/J max) through metallurgical processes is shown to be an index of the dynamic behavior of the material and is useful in obtaining a unique combination of temperature and strain rate for processing and also in delineating the regions of internal fracture. In this method of modeling, noa priori knowledge or evaluation of the atomistic mechanisms is required, and the method is effective even when more than one dissipation process occurs, which is particularly advantageous in the hot processing of commercial alloys having complex microstructures. This method has been applied to modeling of the behavior of Ti-6242 during hot forging. The behavior of α+ β andβ preform microstructures has been exam-ined, and the results show that the optimum condition for hot forging of these preforms is obtained at 927 °C (1200 K) and a strain rate of 1CT•3 s•1. Variations in the efficiency of dissipation with temperature and strain rate are correlated with the dynamic microstructural changes occurring in the material.
1,121 citations