Tests and Finite Element Simulation of Yield Anisotropy and Tension-Compression Strength Difference of an Extruded ZK60 Mg Alloy
Round 1
Reviewer 1 Report
The article presents a lot of interesting and valuable results. However, the form of presentation of the results, descriptions and conclusions are not clearly written. The presented material is chaotic, presented without a well-thought-out plan and order. The introduction and conclusions do not directly refer to the content of the article. I recommend reorganizing and organizing the text before publishing, and summarizing the results as a whole and drawing appropriate conclusions.
Author Response
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Reviewer 2 Report
Magnesium-based alloys have a wide application in the automobile and aircraft industry due to their high specific strength. The authors of the paper "Tests and finite element simulation of yield anisotropy and tension-compression strength difference of an extruded ZK60 Mg alloy" present interesting results about mechanical properties anisotropy and a difference in the compression and tension data. The paper is well written and may be accepted for publication. However, some points of the paper are questionable. The paper should be improved before publication accordingly to the following comments:
- As shown in Figure 1, the microstructure of the investigated alloy has a texture. The authors should calculate and compare the Tailor’s factor (M) for different directions (X, Y, and 45 °). It may approve the difference of the properties.
- How was measured the strain during tension tests using the Gleeble thermomechanical simulator? How was recalculated the true stress from the primary Force vs displacement curve? The details of the methods should be added to the Materials and Experiments part.
- It is known, that significant unevenness of the temperature may be in the tension sample due to specific of the Gleeble system (water cooling of the grips). How was controlled the temperature of the tension sample?
- The friction between the sample’s edges and the dies may significantly influence the true stress – true strain curves [10.1016/j.jallcom.2018.08.010, 10.1134/S0031918X14080031, 10.1179/026708301101510843]. Did the authors consider this fact?
- It is recommended to provide a comparison of the experimental compression and tension stress-strain curves.
- Minor changes are also required:
- The experimental errors of the yield stress values should be added to Table 2.
- The strain rate of 10^-2 s^-1 is hard may be called a “high strain rate” (Line 154) such as strain up to 0.1 is not “large deformation” (caption of Figure 5).
- The typo in Table 1 should be corrected.
Author Response
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Reviewer 3 Report
Dear Authors,
Your paper contains new, excellent and important results.
The methods and simulations are described clearly.
Could you explain (mechanisms?) the differences in (X, Y) uniaxial/compression Yield stress<
Author Response
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Reviewer 4 Report
The paper is interesting and can be published after the following corrections have been made:
- it would be desirable that the scale of the txx and tyy axes should be the same (modify figures 4, 6, 7 and 8)
- it should justify the way of fitting the experimental data to the closed curve, especially the shape of the curve in the second and third quadrants.
- some acronyms are not necessary (e.g. IPETST), if you want to keep them, it would be reasonable to include a list of them.
- what is the meaning of the transformation defined by the tensors L' and L'' (equations 2,3,4 and 5)
Author Response
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Reviewer 5 Report
Plastic deformation of hexagonal compact metals like magnesium alloys occurs by slipping and twinning or both. According to loading rate, slip planes can be modified from basal planes to pyramidal planes. This lead to difficulty to deep drawing and anisotropy of plastic deformation. The yield surface is not symmetric along diagonal in the principal stresses plane. Authors have study this distortion experimentally by tension compression test along transverse, longitudinal and 45° directions. They have modelled it by FE method using continuous evolution between two adjacent yield surfaces for more complex loading : uniaxial , biaxial, loading reverse loading and orthogonal loading. Predictions are compared with linear interpolation. The difference between yield in tension and compression depends on loading mode and orientation of specimen but bin the range 8-48%.
Interest of this work is to use it into deep drawing predictions of magnesium alloys which exhibit some difficulty. The model using plastic cumulative deformation is classic for yield surface evolution in cyclic plasticity and kinematic hardening but its use in this particular case is original.
The weakest point of the paper : it is difficult to evaluate the quality of the analytical model. There is no information about the evaluation of the 6 parameters (in 2D) and the corresponding values. These supplementary informations are necessary for the revised version
The paper is clear in correct English. Many acronyms are not define(see list). Quality of pictures is high.
Page 1
some acronym are not defined HCP; IT
plainified alloys?
Page 2
strong basal texture ?
Karafillis and Boyce models [28,29], references doesn’t correspond. Is the Hencky’s criterion?
Define R-value
Page 3
Acronym EBSD is not defined
“grain size of the material is 4.1504 µm, the standard deviation is 3.2515” (µm) probably too much digits
Page 4 (GB/T 228-2002) ?
Page 5 « 9 groups of anisotropic parameters » what are these parameters? there is less in table 2
Page 7 parameters alpha app and beta app are not defined
Page 9 n is not defined
Page 10 what is the meaning of prime in table 4 ? are A’ and A identical ?
What are the units of A,B,C;D
Page 5 and Fig 5 accumulative and not accumulative
Units of accumulative strain rate are MPa?
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The authors have answered previous comments and improved the manuscript.
The paper may be accepted in present state.
Reviewer 5 Report
The revised version receives the agreement of the reviewer
