Mechanism of {332}<113> Twinning Formation in Cold-Rolled Ti-Nb-Ta-Zr-O Alloy
Round 1
Reviewer 1 Report
This manuscript present a detailed report on the mechanism of {332}<113>twinning in Ti-35Nb-2Ta-3Zr-O(wt. %) 295 alloy. The experimental section was carried out using scanning electron microscopy coupled with the EBSD technique. The post-processed crystallographic information was used for the calculation of the deformation energy of the {332}<113>twinning in the propagation stage. Results were compared with results in previous studies.
The findings are, in general, interesting and worth publishing, the manuscript is well written, and the methods are clearly presented. I would recommend the paper ‘Mechanism of {332}<113>Twinning Formation in Cold-Rolled Ti-Nb-Zr-Ta-O Alloy’ for publication in Materials after minor corrections:
Line 102-103: Plastic deformation was attained through the rotation of grains to the<111>orientation. This is seen for regions (2) to (4) and yet, not for (1) as it represents an area which is far away from deformation zone. Please modify in the text.
Line 112+174: Please correct to 50um and 35.7um..
Line 140: type and not tape..
Line 160: Please insert tau to the equation..
Line 193: Authors estimated the constant k using the partial dislocation model which as stated in the manuscript is dedicated to nanocrystalline grains or nanoscale twins. The twinning, in their propagation and growth stages, are thicker (?) and therefore, the usage of this model is questionable.
Author Response
1.We are sorry for our incorrect writing, and we have made correction according to the Reviewer’ suggestion as follows:
Line 102-103: “… and it is indicated that the grains are approximately rotated to the<111>orientation from location 2 to 4 in Figure. 1. …”
2.We are sorry for our incorrect writing, and we have made correction according to the Reviewer’ suggestion as follows:
Line 112: “… and an average grain size of approximately 50 mm while {332} twins are not observed. …”
Line174: “… thus, the results indicate that L=35.7 mm in grain G2-1. …”
3.We are very sorry for our incorrect writing, and we have made correction according to the Reviewer’ suggestion as follows:
Line 140: “… the Hall–Petch type relationship. …”
4.We are sorry for our incorrect writing, and we have made correction according to the Reviewer’ suggestion .
5.We are very sorry for our negligence of description of the reason for using partial dislocation model, as follows:
Model of Kawabata et al. for {332}<113>twinning included both shear and shuffle, meanwhile {332}<113>twinning accompanies some a″ and w phase, therefore this model is similar to nanoscale twins in some ways. In fact, the model of Kawabata et al. [12] described about twinning dislocation for {332}<113>twinning, while Christian et al.( Christian J W, et al. Progress in Materials Science, 1995, 39(1):1-157.) considered that the dissociation of a lattice dislocation into partial dislocations, and zonal dislocation which is a repeat step of the interface may be regarded as an extended dislocation comprising partial or non-repeat steps separated by "faults", i.e. by regions of higher energy interface. Therefore we have made supplementary specification:
Line 209: “…, Considering that effects of both w and a″ phase [9, 22, 24] on model of Kawabata [12], the constant k in Eq. (1) is…”
We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the manuscript. And here we did not list the changes but marked in red, underline or removal line in revised manuscript.
We appreciate for Editors and Reviewers’ warm work earnestly, and hope that the correction will meet with approval.
Once again, thank you very much for your comments and suggestions
Reviewer 2 Report
1. The introduction is very weak. The literature review should present specific results and findings with those reported in the literature (e.g., line 20-21, and line 29-30).
2. The paper is full of grammar errors.
Line 44: Lai et al [22].
Line 59 needs to add ‘.’ in the end of the sentence.
Line 102 Figure. 2
Line 140 Hall-Petch tape relationship
3. The authors should stress more the novelties of their work in the abstract and in the introduction. E.g. It should be mentioned mechanism and theory on how ⍺״ martensite effects the deformation energy of the twin formation.
4. In the section of materials and methods, it should be explained how to add oxygen in ingots, and present a composition of alloys processed in the study. How was the composition determined? Exact oxygen level is critical.
5. Line 83-84: What does it mean ‘However, a solution heat-treatment part in the same sample was…. i.e., interrupt cold-rolled plate.’ It should be explained clearly with a specific reason.
6. I do not see any misorientation data in figure 2. It should be explained how to get misorientation data mentioned in line 104-105, with reasonable data.
7. In figure 2, how can it possibly include more deformation bands in position 3 than that in position 4. Basically, twinning is continuously activated during plastic deformation. Therefore, it is hard to understand a smaller fraction of deformation bands in fully deformed area (position 4) when compared to that of the area with the relatively small amount of strain (position 3).
8. Line 114, ‘The {332}<113>twinning forms at the early stage of deformation.’ How is ‘the early stage of deformation defined?’ It should be presented with a specific amount of strain.
9. With the data presented in the result, I cannot assume that the deformation bands formed in microstructure are {332}<113>twinning. One must provide specific data to support the author’s explanation on the twin system.
10. Line 136-137 ‘The mechanism of {332}<113>twinning is not clarified today [22],’ I don’t understand this sentence. Clarification of these types of comments with specifics is required.
11. Line 140 ‘the Hall-Petch type relationship(?) is suitable for twinning direction since {332}<113>twinning ….’ It is not true. Hall-Petch relation is about the correlation between grain size and yield strength of materials.
12. Line 144-147, ‘The present study focuses on ….’ This should be mentioned in Abstract or introduction.
13. Line 212-214, ‘Their results [36] was less than our results although the relationship …..’ I do not understand this part. It must be corrected clearly.
14. Line 258-273, ‘Metastable beta-type Ti-Nb base….’ I do not see any reason why the author mentions literature reviews in the section of discussion.
This paper could very well be suited for this journal, but not without major revisions. In its present form is is weak due to the poor writing quality, lack of proof reading, and a general lack of detail in many statements critical to the paper’s impact. The topic is of interest for the readers. However, it is not easy to understand what the authors are trying to explain, due to lots of grammatical errors in their writing. Furthermore, they need to provide specific data to support a formation of twin and to verify their explanation on it.
Author Response
1.Thank you for your comments. The correction was follows:
Line 20-23: “…since the alloys exhibit low Young’s modulus (30-40Gpa) [1, 4, 6] and an optimal combination of strength (more than 500MPa roughly) and ductility (more than 15%) [6, 7]. …”
Line 30-31: “…The {332}<113>twinning exhibits superior mechanical properties such as high elongation percentage (40% in Ti-Mo alloy) [14]) and high strength(yield strength 750MPa roughly in Ti-Mo alloy) [15]. …”
2.It is our negligence and we are sorry about this. According to comment, the corrections have been made as follows:
Line 45: “Recently, Lai et al. [22]. proposed …”
Line60: “Plastic deformation energy is usually applied to investigate the material processing [28, 29]. Recently, …”.
Line 102 Figure. 2 was corrected.
3.We have added this part according to the Reviewer’s suggestion as follows:
Line 15-17: “…It was first time to discuss mechanism of {332}<113>twinning formation based on deformation energy using Hall-Petch type relationship.”
Line 77-79: “…. This paper attempts to analyze the mechanism of {332}<113>twinning formation from deformation energy using Hall-Petch type relationship for the first time.”
4.Thank you for this comments, and we have re-written this part according to the Reviewer’s suggestion as follows:
Line 78-8: “… and prepared in a vacuum arc furnace, oxygen content was controlled through addition of TiO2. And the oxygen content was determined by inert gas fusion-infrared absorption method. Subsequently, …”
5.Thank you for comments. According to comment, related content have re-written them as follows:
Line 86-87: “…And operation of rolling was interrupted, then the cold rolling bite zone was obtained, where was measured. …”
6.The explains about misorientation data was as follows:
Line 111-113: “…and the misorientation along the white arrow lines denoted as 1, 2, and 3 in Figure. 2 (i-k) are close to 50.4°, and this characterizes the boundaries of {332}<113>twins. …”
7.It is our negligence. According to comment, explains have been made as follows:
Line 116-121:”… Compared Figure. 2 (e) with Figure. 2 (g), it was seen that the numbers of lamellars in Figure.1 (e) was less than that of lamellars in Figure. 2. (g). The main causation was that Figure. 1 (g) lied by the center of thickness, meanwhile Figure. 2 (e) lied by surface of thickness. Besides, there are ternary {332}<113>twinning in white dot line box and imprints of coalescence of twins (or vanishing of twin boundaries) in grain marked G4-1 in Figure.2 (g). …”
8.It was our negligence and we are sorry about this. According to comment, the improvement have been made as follows:
Line 126-127: The {332}<113>twinning forms at the rolling initial stage.
9.We have added three figures in Figure. 2 according to the Reviewer’s comments. In term of new figures shown in Figure. 2 (i-k) and results of literatures [22, 25], the deformation bands formed in microstructure are {332}<113>twinning.
10.We are very sorry about this. It was our negligence and the correction was follows:
Line 148: “…The mechanism of {332}<113>twinning formation is not clarified today [22]. …”
11.It was our negligence to explain it in detail and we are sorry about this. But “…the Hall–Petch-type relation…” is really true. In literature [30] ( Wang, S., et al. Variant selection criterion for twin variants in titanium alloys deformed by rolling. Acta Mater. 2012, 60, 3912-3919.), it was names “the Hall–Petch–type relation” in its abstract. For my poor English, the detailed deduction of original text is as follows in [30] (page number:3-5) :
“To calculate this plastic deformation energy in a grain, some assumptions were made: the material is an ideal (i.e., no strain hardening) rigid-plastic body. The material obeys the Von Mises (VM) yield criterion (here, each type of twin has its own yield stress (denoted by sy) expressed in the sample frame): the stress applied to a grain is the same as that applied to the sample (Sachs assumption). The width of the sheet is assumed large compared with the length of the arc of contact between the metal sheet and the rolls so that one can assume that rolling corresponds to material flow in plane strain in the principal axes 1 rolling direction (RD) and 3 normal direction (ND), and the sample coordinate frame was shown in Figure .1. The components of the stress tensor are supposed to remain constant in the thickness. the calculations are made at the neutral fiber.
12.It was our negligence and we are sorry about this. And it was corrected as follows:
Line 156 “… The next mission was elucidating …”
13.It was our negligence and we are sorry about this. And it was re-written as follows:
Line 225-229: ”… Although the values of deformation energy in [36] was less than our results of deformation energy, the method of calculation for deformation energy was similar to our method. …”
14. It was our negligence. These reviews can support our conclusions. And it was corrected according to comments as follows:
Line 273-274:
“From above reviews, it was seen that there were obvious difference between deformation energy of “deformation bands” [58] and that of “α″ phase” formation [57]. The speculation is as follows.”
We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and framework of the paper. And here we marked in red in revised manuscript.
Round 2
Reviewer 2 Report
Minor revisions
Comments for author File: 
Comments.pdf
Author Response
Point 1: Line 16: ‘It was first time to discuss mechanism…’ : It has been investigated on the formation of [332]<113>type twinning in several studies, but it is not clear to explain the mechanism.
Response 1: Thank you for your careful work, we have corrected this as follows:
Remove this sentence (line15-17), and add a new sentence:
lin17: ‘… This can help clarifying the mechanism of {332}<113>twinning formation further.’
Point 2: All figure captions must be corrected (ex, Fig.1 or Figure 1) .
Response 2: It was my negligence. Thank you for careful work. These fault have been corrected as follows:
Line92: ‘… shown in Figure 1. …’
Line144: ‘… as G2-1 in Figure 2. (c). …’
Line174: ‘… Figures 2. (b) and 2. (c) … ’
Line178: ‘… shown in Figure 1. …’
Line190: ‘… is illustrated in Figure 3. (a). ’
Line201: ‘… and G3-1 (as shown in Figure 2.) are …’
Line202: ‘… as shown in Figure 3. (b).’
Line207: ‘… Figure 3. Schematic illustration …’
Author Response File: Author Response.pdf
