Hot Deformation Characteristics of 18Cr-5Ni-4Cu-N Stainless Steel Using Constitutive Equation and Processing Map

Round 1

Reviewer 1 Report

The strength of the article is the experimental part, especially regarding structural analysis (including SEM and TEM). However, the use of the results is considerably unbalanced. The overall impression is somewhat confused. The article should be treated more carefully and unambiguously (in terms of description of results).

Rather, the title should be:Effect of Nitrogen on Deformation Behavior and ... ; workability/formability data from the comprossion testing are not sufficiently meaningful.

The effect of nitrogen has to be studied in more details compared to a "nitrogen-free" steel (not only using a single literary data about its activation energy).

The chapter describing the flow stress model could be substantially shortened (and the final equation better explained - see the Conclusions). On the contrary, the energy disipation diagram should be presented in more detail.

How can you explain the shape of some flow stress curves in Figure 4 (sharp stress increase at high strains and strain rates)?

The Q-value was calculated using the peak stress (Chapter 3.3), sigma_s stress (?), or flow stress data with a strue strain of 0.5 (conclusions)?

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript “Effect of Nitrogen on the Hot Deformation, Hot Workability and Microstructure of 18Cr-5Ni-4Cu Austenitic Stainless Steel” study the hot deformation characteristics of the Cu-bearing N-alloyed stainless steel at different temperatures and strain rate ranges.

In my point of view, the paper is well structured. The introduction provides an interesting information, with a extensive bibliographic review, the methods and experimental part is well explained and described, and the results are clear. The conclusions resumes the work accomplished during the investigation, and them are supported by the work made previously by others authors.

I would like to recommend it for publication with the following minor considerations:

Some editorial errors must be corrected, for example in equation 13

Lines 142-146. The paragraph should be revised to conform to what is seen in Figure 4:

“The strain rate is 10 s-1, and the stress-strain curve is a dynamic recrystallization type. At the beginning of the stress-strain curve, the stress increases sharply with increasing strain, decreases after reaching the peak value, and finally stabilizes. When the strain rate is less than 1 s-1, the stress-strain curves are a dynamic recovery type, and the stress increases sharply with increasing strain. When the strain reaches a certain value, the stress increases”.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

My comments were mostly not reflected in the manuscript. The explanations from the coverletter were also little reflected in manuscript. Moreover, they are sometimes questionable (eg the effect of precipitation at the highest strain rate on stress-strain curves).

Response 1: The main purpose of this thesis is to explain the effect of the precipitation of nitrogen-containing steel on the relative thermal compression. What "relative thermal compression" means?

Most of my requirements were "resolved" by referring to the results of the experimental papers published in the next paper.

Improvement of the clarity of the text is insufficient - see eg the selection of data for the Q value calculation (no explanation).

Some equations even worsened (illegible strain rate symbol).

Author Response

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Author Response File: Author Response.pdf

Round 3

Reviewer 1 Report

I appreciate the modified title.

Problems with the stress-stress curves' shape were explained in a complicated way. According to my experiences, the effect of barelling of the sample at high strains is often decisive, but it's a matter of opinion.

Illegible strain rate symbols were corrected.

Thermal compression - I recommend the common term "hot compression".