Effect of Prior Cold Reduction of C–Si–Mn Hot-Rolled Sheet on Microstructures and Mechanical Properties after Quenching and Partitioning Treatment

Round 1

Reviewer 1 Report

Scientific work on 16 pages contains 9 figures, 2 tables and 33 literary references.

The article presents the results of studies of the microstructure and mechanical properties of samples from sheets of hot-rolled steel 0.2C-1.7Si-1.9Mn, obtained by cold reduction of 35% and 75% wt.% at an annealing temperature of 810°C. The samples were subjected to heat treatment "Quenching and partitioning (Q&P)", which is promising for high-strength steels.

 

1. The content of the work sufficiently corresponds to the subject and profile of the journal.
2. The originality and novelty of the material proposed by the authors of the article are at a satisfactory level. System steels 0.2C-1.7Si-1.9Mn and "Quenching and partitioning (Q&P)" heat treatment are known. At the same time, there are elements of scientific novelty, due to the fact that the effect of preliminary cold reduction on the microstructure and mechanical properties of steel after Q&P has not yet been studied enough. It was found that specimens with a cold reduction of 35%, compared with specimens with a reduction of 75%, have smaller grains of recrystallized ferrite, a smaller average grain size of retained austenite, and better mechanical properties.
3. The practical significance of the work is due to the possibility of using the results obtained in the article in the conduct of research and development related to improving the performance properties of modern high-strength steels by pressure treatment and heat treatment "Q&P".
4. The quality of the analysis of the problem and the validity of its relevance in the introductory part of the manuscript are at a satisfactory level.
5. The task has been completely solved.
6. The results obtained in the article are quite correct and their discussion was carried out in accordance with existing scientific concepts. Possible discussion points in the article do not go beyond the usual scope of scientific articles.
7. The sequence (logicality) of the presentation is generally satisfactory and fits the standard requirements of scientific journals.
8. The style of presentation corresponds to the scientific nature of the material.
9. The design of the article and its volume approximately correspond to accepted standards, figures and tables correspond to the topic being presented and are appropriate for illustrating the text, most of the literary sources are recent publications in specialized journals. The degree of self-citation is acceptable.

 

Notes:

There are no fundamental remarks on the content of the article. There are notes on the sequence of presentation:

1. In the caption to figure 3, the designation of figure 3b is missing. Replace "... 75%-Q&P sample" with "(b) 75%-Q&P sample".
2. The first paragraph of the section “5. Conclusions" is desirable to remove, as it repeats the information contained in the section "2. experimental procedure.

CONCLUSION: The article can be accepted for publication after the elimination of minor comments.

Author Response

Comment (1): In the caption to figure 3, the designation of figure 3b is missing. Replace "... 75%-Q&P sample" with "(b) 75%-Q&P sample".

Response: In the caption to figure 3, the designation of figure 3b has been changed to “Fig. 3. SEM micrographs of (a) 35%-Q&P sample and (b) 75%-Q&P sample. M₁, M₂/A, R-F, UR-F and RA in figures refer to primary martensite, secondary martensite/retained austenite, recrystallized ferrite, unrecrystallized ferrite and retained austenite, respectively.” (Line 3, page 7).

Comment (2): The first paragraph of the section “5. Conclusions" is desirable to remove, as it repeats the information contained in the section "2. experimental procedure.

Response: The sentence “This paper investigated the microstructures and mechanical properties of Q&P samples prepared with 35% and 75% cold reduction 0.2C-1.7Si-1.9Mn wt% sheets at the annealing temperature of 810°C. The conclusions are as follows:” has been deleted.

Reviewer 2 Report

The article highlights peculiarities of the microstructures and mechanical properties of quenching and partitioning samples prepared with 35% and 75% cold reduction of 0.2C-1.7Si-1.9Mn wt% steel sheets followed by annealing at a temperature of 810°C. The authors showed that the 35%-Q&P sample presented better total elongation and a higher product of strength and elongation (PSE) than the 75%-Q&P sample did. They assumed that the higher PSE of the 35%-Q&P sample may be related to the higher content and uneven size distribution of retained austenite.

 

The article is interesting, but a number of shortcomings need to be corrected:

1. It would be good to describe the state of residual austenite (thin-film retained austenite and blocky retained austenite) and its effect on the properties of steel.
2. Font size in Figures 1a, 4c, 7, 8 should be increased.
3. In F 5, it is impossible to see the magnification scale.
4. The authors should put the Figures so that they do not overlap (Fig. 1a and 1b, 3a and 3b, 5a and 5b, 5c and 5d, 9c and 9d overlap).
5. More new References (2019-2022) should be added. For example https://doi.org/10.15407/ufm.20.04.620

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors took into account the comments of the reviewer and made appropriate corrections to the manuscript.

But in Reference 34 there are a large number of co-authors so it should be added "Z.M. Rykavets, J. Bouquerel, J.B. Vogt, et al. ......."

Author Response

Comment (1): The authors took into account the comments of the reviewer and made appropriate corrections to the manuscript. But in Reference 34 there are a large number of co-authors so it should be added "Z.M. Rykavets, J. Bouquerel, J.B. Vogt, et al. ......."

Response: The reference [33] has been changed to:

[33] Z.M. Rykavets, J. Bouquerel, J.B. Vogt, et al. Investigation of the microstructure and properties of TRIP 800 steel subjected to low-cycle fatigues. Prog. Phys. Met., 20 (4) (2019): 620-633.