Effect of Nb Content on High-Temperature Strength and Precipitates of Nb-Containing Steel
Round 1
Reviewer 1 Report
The author of the article "Research on the influence of Nb content on the high temperature strength and precipitates of Nb containing steel" analyzed the influence of Nb element on the high temperature strength and precipitates of slab.
In my opinion, this paper is relatively comprehensive. There are fewer grammatical errors, meeting the publishing requirements.
1) In the third chapter, you selected four samples to conduct experiments at 1100 ℃ and 1200 ℃. Why did you choose those temperatures?
2) In the conclusion part, add a summary sentence, and then describe the conclusion in sections.
3) Some of the references in the article are far away, so can they be replaced with newer ones? (It is better to quote more articles from MDPI)
Author Response
Dear Processes Editors and Reviewer 1:
Thank you for your useful comments and suggestions on the report of our manuscript. We have revised the paper, and would like to re-submit it for your consideration. We have modified the manuscript accordingly, and detailed corrections are listed below point by point.
Point 1: In the third chapter, you selected four samples to conduct experiments at 1100 ℃ and 1200 ℃. Why did you choose those temperatures?
Response 1: Thermodynamic calculation shows that the initial precipitation temperature of Nb containing carbonitride is 1200 ℃(1473 K)~1100 ℃(1373 K), so 1100 ℃(1373 K) and 1200 ℃(1473 K) are selected to observe the precipitation of Nb (C, N).
Point 2: In the conclusion part, add a summary sentence, and then describe the conclusion in sections.
Response 2: A paragraph has been added to the conclusion “The high temperature tensile strength and yield strength of four kinds of test steels with different Nb content were tested by Gleeble-3500 thermal simulation machine. The morphology and composition of Nb containing precipitates in the test steel were analyzed by transmission electron microscope, and the following conclusions were obtained through thermodynamic calculation.”
Point 3: Some of the references in the article are far away, so can they be replaced with newer ones? (It is better to quote more articles from MDPI)
Response 3: I have added two more recent references, which have been marked red.
Sincerely,
Jingyi Zhou.
Reviewer 2 Report
The paper is studying the impact of Nb content on the high-temperature mechanical response of steel. The authors prepared steel samples with various amount of Nb additions and conducted a series of characterization and mechanical testing to explore the high-temperature mechanical properties of the steel. The data reported can be useful in evaluating this type of steel as a building material. The language of the paper requires thorough and professional editing and proofreading to improve the clarity and readability. There are many major and minor issues needs to be addressed before the manuscript can be accepted.
Major issues:
1, Line 129, what is the reason for the low strength area for sample A? What makes it different from the other 3 samples? For sample B, is the high strength point a measuring error?
2, Line 134, proofs should be provided (such as SEM) to demonstrate that the grains of sample B is finer than that of the sample A.
3, Line 136, in my opinion, the tensile strength of sample C and D are not distinguishable, it may just be the measuring error. Actually, for samples BCD there seems be no difference considering the measuring error.
4, Can the authors add explanations about why the yield strength and tensile strength decrease with temperature?
5, Line 282, Since the paper is about the impact of Nb content, the calculation of Ti compounds here is confusing, the authors are recommended to explain this more clear
6, Line 323, it is somewhat confusing about the role of Ti here since the paper is about Nb. Please clarify.
7, For the conclusion section, the authors are recommended not to itemize the conclusion.
Minor issues:
1, Line 14, it should be more specific that the four steels mentioned here is the same steel with four different Nb contents.
2, Line 18, what does "it" mean here?
3, Line 26-27, "high-strength and low-alloy high-strength", this may be a duplication.
4, Line 29, missing "is".
5, Line 37-41, this sentence needs to be rephrased to make it clear.
6, Line 43-44, please add reference to this statement.
7, Line 48, "Nb Ti" missing "-" here.
8, Line 66, "IF", the full term of the abbreviatioin need to be provided at the first occurrence.
9, Line 73, "equal" should probably be replaced with "consistent" here.
10, Line 76, what does four furnaces of steel mean here?
11, Line 84, what does temperature interval mean here?
12, Line 92, try using passive voice to describe the experiments. A lot of sentences in the manuscript needs to be rephrased.
13, Line 97, why is 373 K/min equals to 274.65 K/s?
14, Line 131, it may be easier to read if the temperature range is expressed from low to high
15, Line 134, the authors are recommended to add references here to explain the Hall-Petch strengthening.
16, Line 176, the authors need to be more specific about which figure "In the figure" is referring to.
17, Line 193, why is sample C here is tested at 1273 K, while the figure caption does not mention it? Is it a typo?
18, Figure 6, the caption should be self-explanatory and provides more details about each subplot, such as which sample it is. Also, the scale bars need to be replotted since they are small and blurry
19, Line 201, this paragraph needs to be moved to the experimental section.
20, Figure 7, the caption should be self-explanatory and provides more details about each subplot.
21, Line 233, this paragraph seems to be describing the same observation as the previous paragraph.
22, Line 271, "the change curves of the four samples are the same as a whole", the meaning of this sentence is not clear.
23, Line 276 and 280, the authors are recommended to use the same temperature unit as in the figure 9.
24, Figure 11, Why does sample D have a much smaller size of the precipitated phase?
Author Response
Dear Processes Editors and Reviewer 2:
Thank you for your useful comments and suggestions on the report of our manuscript. We have revised the paper, and would like to re-submit it for your consideration. We have modified the manuscript accordingly, and detailed corrections are listed below point by point.
Major Point 1: Line 129, what is the reason for the low strength area for sample A? What makes it different from the other 3 samples? For sample B, is the high strength point a measuring error?
Response 1: Because the content of Nb in sample A is the smallest, it can be approximately considered that it does not contain Nb. Therefore, its strength is the lowest, and there is no measurement error for the high strength point from sample B, which is the actual experimental result.
Major Point 2: Line 134, proofs should be provided (such as SEM) to demonstrate that the grains of sample B is finer than that of the sample A.
Response 2: Through the analysis of the metallographic picture in Figure 6, it can be seen that the grain of sample B is smaller than that of sample A.
Major Point 3: Line 136, in my opinion, the tensile strength of sample C and D are not distinguishable, it may just be the measuring error. Actually, for samples B, C, D there seems be no difference considering the measuring error.
Response 3: The tensile strength of samples B, C and D is really difficult to distinguish, because the content of Nb will not have a significant impact on the tensile strength after increasing to a certain amount. The result is the average value obtained through many experiments.
Major Point 4: Can the authors add explanations about why the yield strength and tensile strength decrease with temperature?
Response 4: The high temperature strength of continuous casting slab is one of the important indexes to measure the high temperature mechanical properties of the slab, which is usually expressed by the tensile strength and yield strength curves. The tensile strength of the continuous casting slab refers to the maximum stress of the slab against uniform plastic deformation, which is the criterion to judge whether the slab has cracks; The yield strength is the resistance of the slab to plastic deformation, and is an indicator of whether the slab is easy to plastic deformation.
Major Point 5: Line 282, Since the paper is about the impact of Nb content, the calculation of Ti compounds here is confusing, the authors are recommended to explain this more clear
Response 5: Because the sample steel contains Ti element, according to the research results of other researchers, the carbonitride of Ti is generated before the carbonitride of Nb, and finally forms a composite inclusion of (Ti, Nb) (C, N). Therefore, the thermodynamic calculation of Ti is very necessary.
Major Point 6: Line 323, it is somewhat confusing about the role of Ti here since the paper is about Nb. Please clarify.
Response 6:Because the sample steel contains Ti element, according to the research results of other researchers, the carbonitride of Ti is generated before the carbonitride of Nb, and finally forms a composite inclusion of (Ti, Nb) (C, N). Therefore, the thermodynamic calculation of Ti is very necessary.
Major Point 7: For the conclusion section, the authors are recommended not to itemize the conclusion.
Response 7: The conclusion listed item by item is more helpful for other readers to read and more clear.
Minor Point 1-24:
Response Minor Point: All minor issues have been revised in the manuscript and marked in red.
Sincerely,
Jingyi Zhou.
Reviewer 3 Report
The authors present well written manuscript on properties of Nb containing steel. The experiment is properly designed and the results are clearly presented. I would suggest to adjust the positioning of the Figures 3-5 and its font size
Author Response
Dear Processes Editors and Reviewer 3:
Thank you for your useful comments and suggestions on the report of our manuscript. We have revised the paper, and would like to re-submit it for your consideration. We have modified the manuscript accordingly, and detailed corrections are listed below point by point.
Point: I would suggest to adjust the positioning of the Figures 3-5 and its font size.
Response: We have modified the information in Figure 3-5.
Sincerely,
Jingyi Zhou.
Round 2
Reviewer 2 Report
After the revision, the quality of the manuscript has been greatly improved, I therefore recommend to accept the paper. One minor suggestion the authors can consider is that the scale bars in Figure 6 are too small to read currently, therefore the authors are recommended to enlarge them.
