Optimization of Billet Tube Mold Designs for High-Speed Continuous Casting
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
This paper deals with the design of a copper mould for steel continuous casting. In particular, two type of materials, two different mould thicknesses and two cooling configurations were analysed by using a FEM approach.
The topic is surely of great interest for the journal readers (steelmaking environment) nevertheless the paper sounds more has a technical report than as a scientific paper, therefore some parts have to be improved accordingly to the following suggestions:
-Rows 250 and following. Fig. 5 and 6: these graphs can be put in only one figure.
Similarly Fig. 19 and 20.
-Rows 110-111: A three-dimensional finite element thermal-stress coupling model of the copper wall mould has been established by the Ansys simulation method.
The thermal analysis is followed by a mechanical analysis were the obtained temperatures are used as input, therefore the thermos-mechanical analysis is uncoupled.
Ansys is the trademark of a commercial software for FEM analysis; it is not a simulation method.
-Row 115: Research method
This title does not sound well,probaly material and methods is better
-Row 101: Tab. 1. Is temperature dependence of the listed physical quantities considered? If yes, please put a reference.
-Row 183: which plastic model was used? It seems a simple bilinear model. Please explain this better, in particular the values of E and Et versus temperature has to be reported or a reference has to be cited.
According to a durability analysis, it is well known (see Ref. 4 and 15) that the mould undergoes cyclic thermal loads, therefore in principle also the cyclic softening behaviour of the material (in the case of Cu Ag, please refer to: Benasciutti D. and al. , experimental characterization of a Cu Ag alloy for thermomechanical applications. Part I... Fatigue and Fracture of Engineering Materials and Structure,
-Row 208: Results analysis: also this title does not sound well, please rephrase.
Row 255: The equivalent stress cloud atlas of different material mould copper tubes....
What kind of equivalent stresses are reported? Probably the von Mises stress, nevertheless, as indicated in references 4 and 15 the failure of the mould is due to thermal fatigue and thus a correct approach should require to consider as a reference parameter the total or the plastic strain, as suggested in the cited papers. This aspect has to be discussed in the paper in detail and the final choice has to be justified..
Row 687: Figure 7: the figure is unclear, a zoom of the hottest part has to be added. the legend is simply a copy and past of the Ansys output please modify, enlarge and units MPa must be added.
Similarly, all the others figures reporting equivalent stressess output of Ansys.
-Rows 290 and 323: Fig. 9-12. It seems that a transient analysis was performed, this aspect was not described in Par. 2. Please explain it better.
Rows 208-414: Par. 2 describes the obtained results, without any discussions to interpretate them from a physical point of view or compare with other cases reported in literature. This aspect is particularly evident when a comparison in term of stresses and strain is presented (why different materials or thicknesses or water cooling design produce the reported stresss and strain varaiations?). But also in the case of the comparison in temperature the discussion has to be strengthen. This section has to be completely rearranged and extended to include such discussion, in order point out some more general guidelines helpful in designing similar components. Some of them must also be reported in the Conclusions.
-In all the paper, stress unit MPa and not Pa.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsReview of the manuscript Optimization of Billet Tube Mold Design for High-Speed Continuous Casting by Xiaokai Pang, Huirong Li, Jingqi Wang, Liguang Zhu, Ligen Sun.
In this work, a three-dimensional mold was used to design a mold for casting continuous castings.
There are a number of comments regarding the work:
1. The choice of material for the analyzed molds is not justified in any way. In the introduction there is a mention of molds with various coatings. And it is not clear why the authors chose the compositions given in Table 1. Why were such similar materials chosen?
2. The research methods are not very clearly stated. Lines 116, 123 and 141 say the same thing.
3. The physical meaning of formulas 1-3 is not clear. Authors should double-check them carefully. For example, it is stated that L is the perimeter of the mold cavity, but why is it measured in m2? h is the effective length, why in m2? The designations used are not clear: are h and hw the same thing?
4. Table 1 shows the chemical composition of the mold. However, it is not clear in mass or atomic percentages? Why is the total content of elements not equal to 100%?
5. What is the error of the calculations shown in Fig. 5, 6, 9,19, 20, 23? Doesn't it seem to the authors that all the results, taking into account the error, are identical?
6. Fig. 17 it is not clear what difference the authors wanted to show. A and b are the same.
7. In the conclusions, the authors note the identified difference in temperature of 2.8 ° C. What is the error and how significant is this for the performance of the mold?
In general, I think that the work is presented at a low level and cannot be published in this form. I recommend that the authors completely rework the manuscript.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsAlthough the proposed manuscript is interesting, there are enough weaknesses that need to be improved. This based on the following:
· The authors should better review the title is very long
· The summary is very disorganized, the authors must address it to the topic where they include a brief background of the topic to be addressed, followed by the objective, methodology, results, etc. the abstract should be reviewed again because it is very general and the objective is not clear
· The scope of the study is not well defined, the authors could better express it in the abstract
· Authors in keywords must select WORDS and not phrases: high casting speed, water slots structure of mould
· The introduction is very poor, it must be enriched and the authors must integrate more up-to-date literature.
· Line 123: you must separate the numbers from the units
· Line 122: The word assumptions must be changed by another synonym that allows you to enrich your hypotheses.
· The images of the geometric model are of poor quality
· Line 148,152,157,163 etc: Change the word formula to equation
· The mechanical properties and chemical composition of the alloys are theoretical or how they were obtained, the authors must indicate or make reference.
· In Table 1, was the chemical composition reported in weight percentage? because the correct thing would be wt. %
· Figures 5 and 6 could be combined to observe in better detail when the surface is hot or cold in the molds.
· In figure 9 reference is made to a window but the image is too small that it is not adequately appreciated.
· All simulation figures are of low quality, the authors should review how to present better quality.
· The results only present description of the images and graphics. The results should be discussed with articles from the literature and see what the research is contributing.
· The conclusions are very poorly stated, it is not possible that the authors do not think of the reader. Putting conclusions in a paragraph is not correct, the conclusions must be specific and not extensive.
· The authors present 21 references. It is recommended that the authors review the requirements requested in this journal to make references; For example, the year is not in parentheses, the authors begin with their last name, the punctuations must be used appropriately, et al will not be used, nor will "pp" be used, the name of the journals is abbreviated, etc. Authors must enrich the number of references and most current preferences.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for Authors
Comments 1: Fig. 5 and 6: these graphs can be put in only one figure. Similarly Fig. 19 and 20.
Response 1: Thank you very much for your comments. We have combined Fig. 5 and 6 and
subsequent similar images according to your opinion.
OK
Comments 2: A three-dimensional finite element thermal-stress coupling model of the copper wall
mould has been established by the Ansys simulation method.
The thermal analysis is followed by a mechanical analysis were the obtained temperatures are used as
input, therefore the thermos-mechanical analysis is uncoupled.
Ansys is the trademark of a commercial software for FEM analysis; it is not a simulation method
Response 2: We have made modifications based on your comments. In this study, the mould has been
analysed by indirect coupled simulation in ansys software. The results of the modifications have been
shown in rows 126-128.
OK
Comments 3: Research method This title does not sound well,probaly material and methods is better.
2
Response 3: We have been replaced the research method with material and method according to your
opinions.
OK
Comments 4: Tab. 1. is temperature dependence of the listed physical quantities considered? If yes,
please put a reference.
Response 4: Tab. 1. has been compiled by referencing the relevant sources, and the specific references
have been indicated in the text.
THE REVIEWER DOES NOT SEE IN TAB 1 AND IN THE TEXT ANY COMMENT ON THE TEMPERATURE DEPEDENCE OF THE LISTED PARAMETERS.
Comments 5: which plastic model was used? It seems a simple bilinear model. Please explain this
better, in particular the values of E and Et versus temperature has to be reported or a reference has to
be cited.
According to a durability analysis, it is well known (see Ref. 4 and 15) that the mould undergoes
cyclic thermal loads, therefore in principle also the cyclic softening behaviour of the material (in the
case of Cu Ag, please refer to: Benasciutti D. and al., experimental characterization of a Cu Ag alloy
for thermomechanical applications. Part I... Fatigue and Fracture of Engineering Materials and
Structure, 2018, 41(6), pp. 1364–1377) (it is not necessary to cite this paper, but please read it).
Authors area asked to explain better way the choose to model the material with a more simple and less
realistic approach.
Response 5: In this paper, E and Et have been calculated by JMatpro software according to the model
components. In the article, rows 222-223 have been explained. 2) Currently in the continuous casting
production process, the main material of billet mould is deoxidised phosphorus copper, the main
material of bloom mould is Cu-Ag and the main material of slab is Cu-Cr-Zr. Because Cu-Cr-Zr
material strength is higher; Cu-Ag material has high strength and good thermal conductivity. With
the development of high casting speed, the requirements for the strength and thermal conductivity of
the mould are getting higher and higher. Therefore, this paper selects deoxidized phosphorus copper
and Cu-Ag materials for simulation analysis. The explanation has been given in rows 132-140.
THE REVIEWER SUGGESTED THE AUTHOR TO READ AND STUDY THE ABOVE MENTIONED PAPER WHERE IT WAS OBSERVED THAT IS IMPORTANT TO CHOOSE A SUITABLE MATERIAL MODEL IN ORDER TO PERFORM A RELIABLE DURABILITY ANALYSIS. READING THEIR ANSWER IT SEEMS THAT THE AUTHORS DID NOT READ THE PAPER OR DID NOT UNDERSTAND IT. WHY A MATERIL MODEL OF THE CYCLIC PLASTICITY BEHAVIOUR OF THE MATERIAL WAS NOT USED?
Comments 6: Results analysis: also this title does not sound well, please rephrase.
Response 6: We have modified the results analysis to the results and discussion according to your
opinion, and displayed it in yellow.
OK
Comments 7: What kind of equivalent stresses are reported? Probably the von Mises stress,
nevertheless, as indicated in references 4 and 15 the failure of the mould is due to thermal fatigue and
thus a correct approach should require to consider as a reference parameter the total or the plastic
strain, as suggested in the cited papers. This aspect has to be discussed in the paper in detail and the
final choice has to be justified.
Response 7: The equivalent stress reported in this paper is von-Mises equivalent stress, which has
been modified in this paper, and the comparative analysis and detailed discussion have been carried
out.
AUTHORS DID NOT ANSWER TO THE REVIEWER COMMENT. WHY TOTAL OR PLASTIC STRAIN WAS NOT USED?VON MISES STRESS IS NOT THE SUITABLE PARAMETER TO ASSESS THE COMPONENT DURABILITY, UNLESS IT IS USED ONLY TO PERFORM A PRELIMINARY COMPARISON , THAT HAS TO BE FOLLOWED BY A MORE ACCURATE ANALYSIS WHERE SEVERAL HEATS ARE SIMULATED UP TO STABILIZATION OF THE MATERIAL.
Comments 8: the figure is unclear, a zoom of the hottest part has to be added. the legend is simply a
copy and past of the Ansys output please modify, enlarge and units MPa must be added. Similarly, all
the others figures reporting equivalent stressess output of Ansys.
Response 8: According to your opinion, we have added a local enlarged image to Fig.7 and similar
pictures, and have changed the pressure unit to Mpa.
OK
Comments 9: Fig. 9-12. It seems that a transient analysis was performed, this aspect was not
described in Par. 2. Please explain it better.
Response 9: Thank you very much for your comments. We have explained and analyzed the
3
transient analysis according to what you said, and marked it yellow in the text.
I AM NOT ABLE TO FIND THIS EXPLANATION
Comments 10: Par. 2 describes the obtained results, without any discussions to interpretate them
from a physical point of view or compare with other cases reported in literature. This aspect is
particularly evident when a comparison in term of stresses and strain is presented (why different
materials or thicknesses or water cooling design produce the reported stresss and strain varaiations?).
But also in the case of the comparison in temperature the discussion has to be strengthen. This section
has to be completely rearranged and extended to include such discussion, in order point out
some more general guidelines helpful in designing similar components. Some of them must also be
reported in the Conclusions.
Response 10: According to your opinions, we have analysed and explained the temperature field,
stress field and longitudinal displacement from a physical point of view, and discuss them with
reference. In the conclusion, the mould design criteria suitable for high-speed continuous casting have
been summarized. In the paper, it has been yellowed.
OK
Comments on the Quality of English LanguageI am not too qualified to give a comment, nevertheless in my opinion the quality of the English is poor, expecially in the modified text.
Author Response
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Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThanks to the authors for revising the manuscript.
But I still have questions. The authors carry out mathematical modeling in which the basic equations on which the model is based play a decisive role.
1. Equation (1), used by the authors with reference to the source [22]. The source itself [22] does not contain this equation. The equation includes two coefficients A0 and B0. The unit of which are not specified. But, even if we assume that the coefficient A0 is measured in MW /m2, it is not clear how q (is the heat flux density between casting) has the dimension MW /m2 if the second term is in MW /m2 s1/2?
2. Dimension and equation (2) itself have no physical meaning.
3. The unit of the hw is not specified (Equation 3).
4. When using equation (4), the authors refer to two works. Work 23 is from one of the co-authors, but it does not contain this equation. The second work [24] is not publicly available.
I still think that the work in this form cannot be published.
Author Response
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Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors have attended to most of the observations, but in the discussions section the information is weak, they should correct this section by supporting it with bibliographical references.
The references must be reviewed, they only have 26 references, the punctuation and format of the references must be corrected as indicated in the journal. The name of the magazines must be abbreviated.
In the conclusion section the first paragraph should be eliminated.
After this the article could be published in the journal.
Author Response
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Author Response File: Author Response.pdf
Round 3
Reviewer 1 Report
Comments and Suggestions for AuthorsIt is opinion of the reviewer that for a correct thermomechanical simulation the temperature dependence of the material parameters has to considered and clearly documented, moreover a strength analysis has to be performed considering the total strain and not the von Mises stress, unless only a preliminary comparative analysis is performed. This aspects have not been yet clarified in the paper.
Author Response
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Reviewer 2 Report
Comments and Suggestions for AuthorsAccept in present form
Author Response
Thank you very much for your acceptance.
Reviewer 3 Report
Comments and Suggestions for AuthorsAfter reviewing the observations of the authors. the manuscript can be accepted for publication
Author Response
Thank you very much for your acceptance.
Round 4
Reviewer 1 Report
Comments and Suggestions for Authors
We have obtained the thermal-physical performance parameters of the model by reference.
The chemical composition and thermal-physical performance parameters of different materials for the copper wall of moulds have been given in Table 1[25].
Table 1 reports only constant values of the thermo-physical parameters, without any variation with the temperature, moreover the reference [25] is an auto-citation.
and the mechanical performance parameters of the model by Jmatpro software.
In Figure 4 the negligeable variation of the Poisson ratio with temperature is reported, nevertheless it well known that this parameter does not vary significantly with temperature. On the other hand the variation with temperature of the most important parameter, the yield tress, is not reported. Please add it and put it together with the Young’ modulus and CTE in a single figure with three different scales.
When the mould works in continuous casting, the working time of the mould ends with the stop
of the casting. It is not always in a continuous working state. Therefore, it is not appropriate to use
total strain or plastic strain to study this behavior. In addition, this paper focuses on the design and
analysis of the mould, which is currently in the design stage and has not been applied in practice.
Therefore, in this paper, the von Mises equivalent stress has been investigated.
In the introductions the authors have written:
Zhu N et al. [15] optimized and improved the taper of the mould copper plate, the performance of the flux powder, and the superheat of the molten steel for Nanjing Iron and Steel Co., Ltd. After the improvement, the service life of the mould copper plate had been doubled, the life of the wide side copper plate had been increased by 295 heats, and the life of the narrow side copper plate had been increased by 349 heats.
Thus they are aware of the fact that the service life of a mould it is not constituted by one heating, but by several heatings, thus a thermal fatigue approach is necessary.
The same authors cite Ref. 4 (Park JK and al., 2002); in this paper it is pointed out that the mould undergoes a cyclic thermal loading, due to the metal oscillation (high frequency micro-cycles), superimposed to the low frequency macro-thermal cycle due to the subsequent heatings. Please notice that in that paper durability is evaluated in terms of plastic strains (i.e. see Tab.IV).
Author Response
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