A Novel Design to Eliminate Lüders Band in Medium-Mn Steel and Its Microstructure-Property Relationship

Round 1

Reviewer 1 Report

Very interesting work. When the results obtained through the use of multiple test methods can be connected and clarified, then the conclusions are easily drawn and have weight.

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Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

MS Crystals_2429574-v1

"A novel design to eliminate Lüders band in a cold-rolled medium-Mn steel and its microstructure-property relationship" by R. Liu, Z. Hu, C. Lin, D. Yang, X. Gu, X. Xu, J. Guo

The paper proposes a novel medium-Mn steel composition and an associated thermal treatment which successfully maximize the combination of strength and ductility and, at the same time, eliminate Lüders bands.

The structure of the work is clear, the arguments are well presented in a logical sequence, the experimental work is good and well documented and explained.

Minor revisions are needed.

1) A first recommendation is concerned with the English style which needs to be revised throughout the whole text and especially the Abstract, which gives the reader the first impression about the work. There are also some misprints that should be amended.

2) A second recommendation for improving the readability of the tensile data is to collect all them (both for #1 and #2 treatments) in a table instead of listing them in the text. This permits an easier comparison when the comments and observations are read from the text.

 

3) A general question: what about the microstructure of the hot strip coiled at 650°C before cold rolling? Could it be useful to add some detail on it?

 

 

Below some specific observations:

line 42-43: The acronyms UTS and TE should be defined in the introduction for the sake of completeness

line 57 J/cm² instead of J/cm2

line 177: caption of fig. 5 - #2 annealing (instead of #1)

line 138: all thermal treatments-> it is better to add a table with YS UTS EL YPE vol fract austenite for both the #1 and #2 tensile tests (see point 2 above).

line 191 Fig. 6b: one of the curves in the plot, perhaps 1#IA790, is not labeled

lines 216 and 217:  nm instead of µm

line 226: 2#Q810 instead of 2#810

line 237 and caption of Fig. 8: the reference to the IPF direction in Fig. 8 (presumably ND) is missing

Line 237: regarding the observed randomness in the orientation of austenite grains in the microstructures, it would be useful to specify that the evaluation is only qualitative and based on the IPF maps. 

Line 302 - Fig. 9d: for the sake of clarity it would be useful to add a label "ferrite" and "austenite" in the range of Mn concentration points 1 to 5 and 6 to 10, respectively

Line 320: "Due to"

Line 363 Fig. 10a: the label of the horizontal axis should be "True strain" instead of "Ture strain"

Line 391: the absence of Lüders bands in the 2#Q910-IA730 specimen could be also explained, besides the effects of morphology and austenite stability, also from the observation that before the tempering treatment at 730°C the steel has been fully austenitized and quenched to a lath-like microstructure composed of martensite and austenite. The subsequent (partial) tempering of the lath-like martensite leaves in the resulting ferrite a dislocation density which is sufficient to eliminate the Lüders bands. On the contrary, in the case of intercritical treatment (2#Q810-IA730) the block-like ferrite has a much lower dislocation density since it is not originated by a tempered martensite.

Line 414 "strain" (not stain)

Line 418 "intercritical"

Lines 424-426: point #5 of conclusions - the sentence is not clear and needs to be rewritten.

The English style which needs to be revised throughout the whole text and especially the Abstract, which gives the reader the first impression about the work.

There are also some misprints that should be amended.

Please improve the clarity of some sentences that may appear confusing

 

Author Response

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Reviewer 3 Report

A.        Work title In my opinion, the title of the work should be changed. As it stands, it refers to cold rolling. And the research results indicate that the scope of work is much larger. B.         Abstracct:

-            In my opinion, in the summary it would be good to clearly emphasize what was the main goal of the work.

C.      Introduction

-        The introduction is well developed. In my opinion, it would be good to supplement with information from 2-3 publications from the last 4 years, e.g.: https://doi.org/10.3390/met10101375, https://doi.org/10.3390/ma15062013

D.      Materials and Methods

-          The chemical composition of the tested material along with the designation should be given in the table. -          In my opinion, Fig. 1 should be transferred to the results. In the description of Fig. 1, cold rolling was used (“Dilatometric results of cold-rolled steel during the heat treatments….”), and the figures show temperatures in the range of 500-1000C. Please clarify or correct. It is assumed that above 04T of melting, it is a hot rolling process. -          It would be good at this point to include a view of the batch material samples to be tested on the batch material samples.. E.      Results and Discussion -        I would suggest to combine point 3 and 4 and call it "Results and Discussion" because in point 3 and 4 the research results and their analysis are presented. I have no comments on the results of the research and analysis. I would like to know what impact the rolling process itself had. Please also specify the influence of annealing processes on microstructural changes. F.       Conclusions Regarding the conclusions, I believe that they should also be corrected in accordance with the directions given above for the work.  

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Dear authors.

Thank you very much for the additions and corrections made. In my opinion, the article in its current version is suitable for publication. Congratulations.