Effect of Different Thermal Schedules on Ductility of Microalloyed Steel Slabs during Continuous Casting
Round 1
Reviewer 1 Report
The English needs a fine polishing. Please re-work the whole paper regarding the English.
The following corrections contain some hints in which way the English should be inproved.
line 24: delete 'yet'
line 28: rephrase the sentence
line 34: do you mean 'final'?
line 40: 'avoids'
line 43: 'and thus avoid'
line 81: 'were simulated'
line 86: 'were drawn'
line 87: the citation should be no superscript. Please also correct this in the following.
line 92: 'can ensure'
line 100: 'after etching'
line 107-109: rephrase the sentence
line 113-114: rephrase the sentence
line 142: 'are shown'
line 147: '-3' as superscript
line 153-154: rephrase the sentence
line 168: 'characteristics'
line 181: '800 °C'
line 190-191: rephrase the sentence
line 205: 'work of grain boundry nucleation is'
line 208: 'presented'
line 230: 'dispersively precipitated'
Author Response
Dear Reviewer:
Thank you very much for your careful revision of the paper. We have revised the manuscript carefully addressing all the issues raised by the reviewers’ and included point-by-point reply (file attached) as well as included in the manuscript accordingly (highlighted in yellow).
Yours sincerely,
Yang Li
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Dear authors. Your subject is very interesting but also well known. Many publications have been published from this subject. You say that this SSC concept is not widely applied in industry, but I have never heart that it is used in industry. if you know, it is used It would be good if you say more accurately this point. I know that some companies has tested it anyhow, but I have heart that it is difficult to control. Sometimes the results are excellent, sometimes very poor. Do you know why? It also would also be good if you very clearly explain the concept in the paper. You explain it but not very clearly. As I understand your concept, it is: 1) rapid cooling below mould to 600 degrees. 10 C/s. 600 C is still in the austenite region. What happens during that. We have austenite grains formed in the mould but during fast cooling the grain growing is prevented, or what? 2) Holding 2 minutes -> according to TTT curves austenite to ferrite phase transformation is going on. It would be good to have TTT curve too for your steel grade. The ferrite is now distributed randomly, we do not have film-like ferrite. We have acicular or granular ferrite but not film-like. It is good. So the question is how we can get acicular or granular ferrite, not film-like. Maybe we need a fast cooling rate and then stopping and holding as you describe. The precipitates are also forming more randomly because they are forming in the ferrite. Because of high cooling rate, no time to precipitate in the austenite grain size during cooling? Then reheating and so on. I think you should more clearly write the phenomena behind or for different steps in SSC cooling pattern. One question: could it be possible to have slower cooling rate just below Ar3 temperature and then hold it here for 1-2 minutes. How sensitive is the cooling rate? One more thing: you are using reheating not in-situ remelting. Are you used as-cast samples or rolled samples. You need to explain this more, because it is quite different if you use reheated sample or in-situ remelted sample.The grain size and particle behavior are different. One paper says that in SSC control the reason is that the precipitates are forming in the austenite grain boundary and in the film-like ferrite but during reheating the austenite are forming around the precipitates from the film-like ferrite and so the grain boundary is more ductile and more strong, no cracking. Maybe that might happen too? So there are two or more phenomena which could prevent cracking? One question is also are the Gleeble results similar to what are the conditions in casting machine. In the tensile testings the reduction is so big compared to continuous casting and maybe crystallization phenomena are different too. I also wonder why the results in Fig 1 seems to be different than in Fig 2 for example? And you say that austenite to ferrite phase transformation takes place in 700 to 500 C and then austenite to bainite in 600 to 400. So do you mean that we have during 600-500 two reactions in the same time? I also hope that you discuss more widely about this SSC process. Now you have studied only one steel grade and have discussed only about that. I hope you discuss more generally about SSC and how it should be applied in industry, so in general. And in the introduction part you should make more wide review and explain the physical phenomena in the concept more clearly. Now it is abit unclear, at least for me. I hope you continue your work and send this paper again.
Author Response
Dear Reviewer:
Thank you very much for your careful revision of the paper. We
have revised the manuscript carefully addressing all the issues raised
by the reviewers’ and included point-by-point reply (file attached) as
well as included in the manuscript accordingly (highlighted in yellow).
Yours sincerely,
Yang Li
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Dear authors. Your answers are good for my comments. This subject is very interesting and I hope you will continue the research. This method is not so much used in industry mainly because the subject is not known so well. You say that the cooling rate should be as high as about 10 degrees/second to avoid film-like ferrite. This might be so high that it is difficult to manage in industry and could it lead to cracking too? What about vertical-bending casters. They are very popular today. How we should organize this concept for these kind of casters? Do we have time to do this before bending? Bt you have made a good work and I am waiting for your next papers. It is good to have more fundamental information about this phenomenon. Two comments: 1) page 2 - you have cooling rate 10 degrees but the unit should be 10 degrees/second. 2) In the experiments you have started the cooling rate from 1350 degrees. Why so high temperature? After mould, in casting, the slab corner temperatures are much less.
