Microstructural Variation and Evaluation of Formability According to High-Temperature Compression Conditions of AMS4928 Alloy
Round 1
Reviewer 1 Report
I see the work carried out quite good and suitable for publication.
However, there are some shortcomings in the article.
Introductory part should be improved.
The discussion section should be improved.
I will suggest you a few publications for you to develop them.
1. Investigation of vermiculite infiltration effect on microstructural properties of thermal barrier coatings (TBCs) produced by electron beam physical vapor deposition method (EB-PVD)
2. Investigation of oxidation and hot corrosion behavior of molybdenum coatings produced by high-velocity oxy-fuel coating method
3. Comparison of calcium–magnesium-alumina-silicate (CMAS) resistance behavior of produced with electron beam physical vapor deposition (EB-PVD) method YSZ and Gd2Zr2O7/YSZ thermal barrier coatings systems
4. TGO growth and kinetic study of single and double layered TBC systems
5. Investigation of calcium–magnesium-alumino-silicate (CMAS) resistance and hot corrosion behavior of YSZ and La2Zr2O7/YSZ thermal barrier coatings (TBCs) produced with CGDS method
6. Oxidation and hot corrosion resistance of HVOF/EB-PVD thermal barrier coating system
7. Comparison of microstructure and oxidation behavior of CoNiCrAlY coatings produced by APS, SSAPS, D-gun, HVOF and CGDS techniques
8. Performance of single YSZ, Gd2Zr2O7 and double-layered YSZ/Gd2Zr2O7 thermal barrier coatings in isothermal oxidation test conditions
9. Formation and growth behavior of TGO layer in TBCs with HVOF sprayed NiCr bond coat
10. Interface failure behavior of yttria stabilized zirconia (YSZ), La2Zr2O7, Gd2Zr2O7, YSZ/La2Zr2O7 and YSZ/Gd2Zr2O7 thermal barrier coatings (TBCs) in thermal cyclic exposure
11. Evaluation of oxidation and thermal cyclic behavior of YSZ, Gd2Zr2O7 and YSZ/Gd2Zr2O7 TBCs
12. Investigation of the effect of V2O5 and Na2SO4 melted salts on thermal barrier coatings under cyclic conditions
13. Effect of high temperature oxidation on Inconel 718 and Inconel 718/YSZ/Gd2Zr2O7
14. Cyclic hot corrosion failure behaviors of EB-PVD TBC systems in the presence of sulfate and vanadate molten salts
15. Evaluation of Hot Corrosion Behavior of APS and HVOF Sprayed Thermal Barrier Coatings (TBCs) Exposed to Molten Na2SO4 + V2O5 Salt at 1000 °C
16. Isothermal oxidation and thermal cyclic behaviors of YSZ and double-layered YSZ/La2Zr2O7 thermal barrier coatings (TBCs)
17. Investigation of hot corrosion behavior of thermal barrier coating (TBC) systems with rare earth contents
18. Evaluation of Hot Corrosion Behavior of APS and HVOF Sprayed Thermal Barrier Coatings (TBCs) Exposed
19. Hot corrosion behavior of YSZ, Gd2Zr2O7 and YSZ/Gd2Zr2O7 thermal barrier coatings exposed to molten sulfate and vanadate salt
20. The microstructural investigation of vermiculite-infiltrated electron beam physical vapor deposition thermal barrier coatings
21. Isothermal oxidation behavior of gadolinium zirconate (Gd2Zr2O7) thermal barrier coatings (TBCs) produced by electron beam physical vapor deposition (EB-PVD) technique
22. Oxidation behavior of NiCr/YSZ thermal barrier coatings (TBCs)
23. Comparison of microstructures and oxidation behaviors of ytria and magnesia stabilized zirconia thermal barrier coatings (TBC)
24. State of the art thermal barrier coating (TBC) materials and tbc failure mechanisms
Author Response
Response 1: According to the Reviewer’s comment, we complemented and revised the manuscript. Thank you for your kind comments.
According to the Reviewer’s comments, the quality of this manuscript can be improved. Thanks for your comments.
Reviewer 2 Report
This paper has studied the microstructural variation and evaluation of formability according to high-temperature compression conditions of AMS4928 alloy, and uses the optimized results for ring rolling. It is interesting and helpful, but some issues should be polished before the recommendation for publication.
1. Section 2, ‘which is a bulk material forged to Φ500 after performing VAR (Vacuum Arc Remelting) twice.’ What about the forging ratio？
2. In section 2, “one of them was divided into XY, YZ, and XZ planes, cut, and hot-mounted”, the coordinate should be given in a sketch. Furthermore, the position of the compression sample in the forged bulk material should be given.
3. In the ring rolling section, what about the initial microstructure of the ring billet? Is it the same as that of the compression specimen?
4. The dimension of the ring before and after rolling should be given.
5. In some figures, the characteristic described in the manuscript should be marked; for example, ‘In the results of observing the macrostructure, fine cracks of about 7 mm occurred in the lower right part of the cross-sectioned corner.’ If the crack is marked in Figure 15， it would be much easier to understand.
Author Response
Response 1: The forging ratio for forging the billet produced through the VAR (Vacuum Arc Remelting) process to Φ500 is between 1.5 and 2. We modified the manuscript.
Response 2: According to the Reviewer’s comment, we inserted Figure 1 and revised the manuscript.
Response 3: The microstructure of Ti-6Al-4V ring billet is Widmanstätten, the same as that of the compression specimen.
Response 4: According to the Reviewer’s comment, we inserted the contents and revised the manuscript.
“In the ring rolling process, a Ti-6Al-4V alloy with an initial dimension, outer diameter Φ640, inner diameter Φ500, and height 205mm was rolled to an outer diameter Φ700, inner diameter Φ457, and height 259mm.”
Response 5: According to the Reviewer’s comment, we inserted the mark showing the crack in Fig.16.
Thank you for your kind comment.
According to the Reviewer’s comments, the quality of this manuscript can be improved. Thanks for your comments.
Reviewer 3 Report
The paper “Microstructural Variation and Evaluation of Formability According to High-Temperature Compression Conditions of AMS4928 Alloy” is devoted to the analysis of the microstructure and the choosing of the optimal parameters for the thermal deformation treatment of the AMS4928 alloy using processing maps. The paper is well written and the text is clear and easy to read. However, the relevance and the scientific novelty of the paper are doubtful: previously, many studies have been carried out on the topic of determining the optimal deformation parameters at elevated temperatures of the Ti-6Al-4V alloy using processing maps. For example:
10.1016/j.msea.2008.10.020
10.1016/j.msea.2008.11.031
10.1016/j.jallcom.2019.02.046
10.3390/ma15051748
10.1557/jmr.2018.331
10.1007/s12289
-018-1457-9
and others.
So, there are some questions below:
1) The references used in the Introduction are very old. Only 8 references from 30 (~27%) are not older than 5 years. So, the Introduction part should be improved using, for example, the references below:
10.1016/j.jallcom.2020.156672
10.1088/2053-1591/ab31f9
10.1016/j.matchar.2020.110342
10.1016/j.jmrt.2020.03.092
10.1016/j.msea.2020.140651
10.1007/s11837-021-04670-6
10.1088/1757-899X/1107/1/012094
10.1139/tcsme-2018-0276
10.1016/j.jallcom.2018.01.299
10.3390/app11104587
10.1016/j.jmrt.2019.05.018
and others.
The list of references should consist of more than 80% of modern sources. Otherwise, it looks like the topic of the paper is currently not relevant.
2) Figure 3 and Lines 136-137: “This result is due to the difference in internal and external cooling rates after the VAR process of the Φ500 bulk material”.
The difference in the level of the mechanical properties should be explained due to the difference in the microstructure (the texture), but not the “cooling rates”.
3) What equipment was used for carrying out the compression tests? It seems, that at strain rate 1 s-1 (Figure 4c) the actual strain rate at beginning of the deformation was over 1 s-1, that’s why there are peaks at the curves at 0 – 0.1 strain interval. The curves in Figure 4 are poorly distinguishable.
4) How were the true strain – true stress curves determined? Did the authors take into account the friction and the heating of the specimen during deformation?
4) In Figure 6 there are no numerical values for the colour scale.
5) Lines 241-243: “In practice, cracks occurred along the flow localization band as shown in Fig. 11(c), and the unstable regions defined in Fig. 4 and Fig. 10 can be confirmed.”
What cracks are the authors talking about? The scale bars are unreadable in Figure 11.
Why do the authors compare the macrostructure of samples after deformation ε=1.2 and the processing maps for ε=0.6?
6) The efficiency of power dissipation is calculated incorrectly. These values cannot be negative (Figure 10, blue values on colour map).
7) The analysis of microstructure (lines 254-303 and Figures 12-13) is incorrect. It is well known that after the uniaxial compression test the microstructure of the sample is different in cross-section (see 10.1016/j.rinp.2019.102340, for example ). The microstructure that will correspond to the given degree of strain is located in the region of approximately 1/3 of the radius and 1/3 of the height in the cross-section of the deformed specimen.
8) In connection with all of the above, the correctness of the conclusions is also in doubt.
Author Response
Response 1: According to the Reviewer’s comment, we exchanged and added the recent references within 5 years. Thank you for your kind comments.
Response 2: According to the Reviewer’s comment, we revised the manuscript.
“This result is because the microstructure of the external has a narrower lath spacing than the internal due to the difference in cooling rates between the internal and external after VAR processing of the Φ500 bulk material.”
Response 3: According to the reviewer's comments, we inserted the information of the equipment for high-temperature compression test. We exchanged Figure 4 with the higher resolution curves.
In addition, the curve peak at the 0-0.1 strain range is occurred when the plastic deformation of the material is unstable or locally concentrated, as described in section 3.2.1 hot compression test.
Response 4: The basic theory of the dynamic material model used in this study is the model proposed by Prasad and Gegle. The model is based on the energy (G) used by plastic deformation and the energy (J) that causes a change in the microstructure when plastic deformation is performed, depending on the temperature and strain imparted to the material. Based on this, G relates to a dynamically metallurgical mechanism to dissipate heat and J to dissipate power. Therefore, as mentioned in section 3.2.2. Processing map, heat and friction are considered during high-temperature compression in this study.
Response 5: According to the Reviewer’s comment, we modified Figure 6. Thank you for your kind comment.
Response 6: According to the Reviewer’s comment, we marked and modified Figure 12.
High-temperature compression test has been done up to stain ε=1.2, but processing map was drawn about deformation behaviors at ε=0.6 condition. Because the strain ε=0.6 condition is maximum reduction ratio at high-temperature rolling process for forming parts, we selected the strain value and calculated the processing map.
Response 7: In the process of calculating the strain rate sensitivity coefficient through the polynomial equation, the change in slope in each strain rate region of the flow stress becomes the strain rate sensitivity coefficient. Therefore, although the efficiency is theoretically positive, the actual-calculated results can experimentally show a negative value due to the tendency which the strain rate sensitivity coefficient (m) decreases in the region between 0.1s and 1s at 800°C in Figure 6, as reported in various references.
Response 8: According to the Reviewer’s comment, we inserted the modified figures.
Figures 13(a~c) and 13(d~f) explain that there are microstructural differences by dividing the cross section area into a dead zone and severe plastic deformation area, respectively. In addition, in the case of Fig. 14, the difference between the dead zone and severe plastic deformation region was shown through comparison of the prior beta grain size in Fig. 15.
Response 9: We revised and modified the contents of manuscript according to the Reviewer’s comment. The quality of this manuscript can be improved by the Reviewer’s helpful comments. Thanks very much for your comments.
According to the Reviewer’s comments, the quality of this manuscript can be improved. Thanks for your comments.
Round 2
Reviewer 3 Report
The revised version of the paper “Microstructural Variation and Evaluation of Formability According to High-Temperature Compression Conditions of AMS4928 Alloy” were greatly improved and may be acceptance for publication.
