Effect of Cold Rolling on the Microstructural Evolution and Mechanical Properties of Fe-25Mn-3Si-3Al-0.3Nb TWIP Steel

Round 1

Reviewer 1 Report

This manuscript presented the results of experimental rolling tests of a modified TWIP steel to predict Nb addition on the microstructure evolution, deformation mechanism and mechanical properties. The authors have done a valued research work, but to meet the standards of Coatings the paper should be improved. Authors should add some exploanation linked their researches with the journal topic. In the paper I found some inaccuracies that should be explained and corrected:

1. Introduction. After the sentences” “The diameter of solid expandable tubulars need to be expanded by ~15% even by 30% in the downhole through the action of hydraulic pressure or mechanical force, and then the precious inner diameter of the wellbore will be retained to maximum size.” and “After all, the strain-induced martensite has higher stress corrosion sensitivity in the oil and gas environment.” Authors should add an additional literature. Authors. Moreover, the authors did not test the corrosion resistance.
2. page 2, line 90: 20 mm thick sheet, page 3, line 98, is plate, should be sheet. It is not sheet (plate), it’s plate. Over 5 mm in thickness, i.e. plate, below sheet.
3. Authors should add information about rolling parameters: type of rolling mill, diameter of rolls, velocity of rolling, number of passes,
4. The deformation per pass was equal to 5%. That’s why, in the rolling band probably appear non-uniform distribution of strain on the sheet thickness. That’s why Authors should add an additional analysis of the deformation effect on the hardness distribution on the sheet thickness.
5. Poor quality of Figs. 1, 3 and 7.
6. Fig. 5. The elongation is low. What is the possibility of sheet bending?
7. Page 8, line 247, is stee, should be steel.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

A very well written piece of research.

A minor spelling check is required prior to resubmission.

Author Response

The spelling and language of the article has been checked and revised.

Reviewer 3 Report

The manuscript studies the effect of cold rolling on microstructure evolution and mechanical properties of Fe-25Mn-3Al-0.3Nb TWIP steel. While the topic has some interesting findings, it is not suitable for publication in the current version and content. following comments should be considered: 

1- The manuscript was not written in good language and style. Extensive revision is needed by a native English speaker. 

2- You should use the abbreviations in () on page 1: SET. All the abbreviations should be introduced. TWIP.

3- I could not see any twins in Fig. 4a. Please clarify your marking.

4- In figure 7, the quality of the micrograph is very poor. Precipitated particles are not easily distinguishable.

5- The discussion part should be improved extensively, for example, it is well known that twinning is the main deformation mechanism in TWIP steels. But you should explain how it can be affected in your alloys. How are there related together? (dislcoations and twinning) 

6- You did not explain the planes of twins and their effect of them on the properties.

7- The effect of stacking fault energy was not estimated and explained well. Please add the formula for SFE calculation from this reference, and add to the manuscript: https://doi.org/10.1002/srin.202000242

8- What is the mechanism of shear band formation? How we can relate that to dislocation and twin?

9- What is the meaning of fracture mechanics? This is a general expression. 'the fracture mechanism in the static tensile specimens with different rolling strains is always microporous aggregate fracture. '

10- About the role of Nb, you did not have a good discussion and conclusion. Please clarify the role of Nb in your discusison.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The paper is ready for publication

Author Response

Thank you very much for your suggestion.

Reviewer 3 Report

The revised version is better than the previous version. however, in some cases, there are some questions remaining. 

Point 3: Fig. 4: the discussion based on the observations is not enough. The twin indications and dislocation walls. About the dislocation wall, it seems that the indication in Fig. 4d is grain boundary. 

 

Point 7: The new discussion is very good fit to the obtained results. Please also add the equation for calculating SFE from the mentioned reference in the previous comments. Then, you will have a more meaningful comparison with the ranges of SFE you've mentioned to explain the behavior.

Point 10: As you've mentioned, it is already explained in another paper. However, you mentioned that The addition of niobium will not significantly change the plastic deformation mechanism of Fe-25Mn-3Si-3Al steel as long as the existing forms and relative content of carbon and niobium in the steel are well controlled. The reason and explanation about the Ni addition should've improved in view of the plastic deformation while you mentioned there are no significant changes. Some parts of your previously published paper should be cited and explained the reason why you did not see any changes in the plastic deformation mechanism.

 

Additional point: discussion part does not explain all the aspects of deformation. How about texture? What is the interplay of twins, dislcations and texture on the microstructural evolution and mechanical properties of the current cold-rolled Nb added TWIP steel? 

 

 

Author Response

Thank you very much for your careful work. And the manuscript has been revised again according the reviewer's comments.

Author Response File: Author Response.docx

Round 3

Reviewer 3 Report

The current status of the manuscript is appropriate to consider for publication.