On the Superplastic Deformation in Vanadium-Alloyed High-Nitrogen Steel
, Valentina Moskvina, Marina Panchenko, Galina Maier, Eugene Melnikov, Kseniya Reunova, Nina Galchenko and Sergey Astafurov *Round 1
Reviewer 1 Report
The manuscript presents an excellent experimental work based on high-quality, up-to-date equipment and methods for characterization and mechanical testing. The contribution to the domain is novel and deserves publication. The authors demonstrate an excellent expertise on steels, on microscopic characterization methods (SEM, TEM, EBSD), and on mechanical testing methods. The manuscript may thus be accepted provided the correction of the flaws indicated to the authors.
Some language flaws need to be corrected
“intergranular” to be substituted everywhere by “intragranular” lines 106 and 108: delete “An” and “A” beginning the sentence lines 143, 145, 165, 172 : write “corresponding” instead of “corresponded” lines 233, 235: ratio
Author Response
Please see the attachment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
need to correct the degree of number in line: 23, 44, 51, 72, 240, 249
Line 143: what method determined that this is true tension and true elongation? You have to describe a method or make a link
Line 183: on what basis is it concluded that there was no grain-boundary sliding? the article did not conduct a focused study of this mechanism. Describe more about this in more detail.
it would be good if the author separately dwells on the influence of the precipitated phase on the superplasticity of the alloy
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 3 Report
This paper reports achievement of superplastic elongation in V-alloyed high-N steel. The elongation itself is a rigid result, though, the discussion is not considered deeply and soundly. The following points should be reconsidered:
1) The reviewer understand that the sample were recrystallized in the early stage of superplastic deformation. If it is the case,
a) Flow stress usually drops after such dynamic recrystallization, though we cannot recognize such drop in the true stress-true strain curves in Fig.4a insert.
b) Recrystallization behavior in different deformation condition (temperature and strain rate) is different from each other, i.e., different grain size is obtained. The log stigma-log epsilon dot plot shall not be drawn using such different microstructures.
The followings are minor points:
1) After the second time, V-added, high nitrogen, HMS, etc are used in mix and to be unified.
2) grains are not "spherical shape" but "equiaxial shape".
3) Make clear either tensile tests in ambient and in vacuum were performed in the same equipment.
4) Describe how the true stress-true strain curves in Fig.4a insert were drawn.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 4 Report
The manuscript contains interesting results concerning superplastic behavior of vanadium alloyed high-nitrogen steel. The manuscript is well structured and results are clearly presented.
However there are some comments:
The caption of Fig. 1 requires editing. “Figure 1. … Step sizes are 8 μm (a,b) and 1 μm (c,d).“ But Figs. 1c,d show TEM figures not EBSD maps. The mean grain size after annealing Fig. 1e,f is 3 μm. The grain size was measured by EBSD with step size 1 μm. It means that the number of pixels for average grain is too low. Thus the values of mean grain size can be inaccurate. Figure 6 requires editing.Is not clear (Fig. 6b), from the text, for which direction IPF is made. Is it normal direction? Is the texture random also in the direction of the tensile stress (RD direction)?
The phase map (Fig. 6b) shows fine ferritic grains but the other phases (coarse VN, Cr2N) are not visible. Why? Have other phases not been identified due to insufficient spatial EBSD resolution?
Fig. 6c shows LAB (green line) and HAB (blue line) but in the Fig. 6c there are red lines. What do the red lines indicate? HAB?
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
The manuscript has been well revised according with the reviewer's authors comments.
