On the Unique Microstructure and Properties of Ultra-High Carbon Bearing Steel Alloyed with Different Aluminum Contents
Round 1
Reviewer 1 Report
This paper is valuable to reader who want to understand bearing steel. This paper has abundant results related to mechanical properties of bearing steel. I think this paper could be accepted in publication. Before acceptance the following items should be revised.
- In keyword, there are two words such as tempering stability and temperature resistance. It is better to add the definition of tempering stability and temperature resistance in introduction or experiment part.
- In conclusion, the author described that the addition of Al significantly reduced the density of steel. Therefore it needs to provide the density data in this study.
- In Figure 1, Temperature/oC in Y-axis should be changed in direction.
- Other things: select 2 hours or 2 h, of martensite in line 18, Ultra-high Carbon steels in line 77, etc.
Author Response
Dear Editor,
First of all, we would like to thank you and the reviewers of our paper (Manuscript Number: Metals-1283346) for the constructive and informative comments and suggestions. We have carefully considered the reviewers’ comments and suggestions and have modified our manuscript accordingly. The following is our detailed response to the reviewers’ comments and suggestions. For clarity, we have listed the reviewers’ comments below and have addressed them one by one.
Response to Reviewer 1 Comments
Point 1: In keyword, there are two words such as tempering stability and temperature resistance. It is better to add the definition of tempering stability and temperature resistance in introduction or experiment part.：
Response 1: Thank for your carefully work. Considering the reviewer’s suggestion, we have added the definition of these two words in the introduction：
Tempering stability --- When quenched steel is tempered, the ability to resist the decrease in strength and hardness is called tempering stability.
Temperature resistance--- The temperature resistance refers to the properties of a substance that can maintain its excellent mechanical properties under heated conditions. (see section 1, line113 to 115)
Point 2: In conclusion, the author described that the addition of Al significantly reduced the density of steel. Therefore it needs to provide the density data in this study.
Response 2: Thank for your constructive suggestion, we have checked the relevant literature and the results are as follow [23]. With the addition of Al, the density of UHCS-6Al steel (7.10 g/cm3) is 9% lighter than GCr15 steel (7.81 g/cm3), while maintaining high hardness and good wear resistance. (see section 2, line135)
[23] Wang, H.; Chen, Q.M; Zhang. W.L.; et al. Continuous cooling transformation of an ultrahigh carbon steel. Heat Treatment of Metals. 2017, 42, 24-28.
Point 3：In Figure 1, Temperature/oC in Y-axis should be changed in direction.
Response 3： Thank for your carefully work, the direction of Temperature/℃ in Fig. 1 has been revised. (see section 2, Fig. 1)
Point 4：Other things: select 2 hours or 2 h, of martensite in line 18, Ultra-high Carbon steels in line 77, etc.
Response 4：Considering the reviewer’s suggestion, all similar errors in the article have been revised. Use h for all hour, and Ultra-high instead of Ultrahigh.
Finally, thank you for giving us a chance to revise our manuscript. Certainly, we also thank the review’s comments and suggestions. At last, we hope this revised manuscript could bring more to reader.
Yours sincerely,
Wenquan Cao,
Ph. D.
Corresponding author
College of Materials Science and Engineering,
Chongqing University,
Chongqing 400044, China
E-mail: [email protected]
Reviewer 2 Report
Reviewer’s comments Metals-1283346
- Written language can be improved.
- Page 2, line 49:
“However, at present time no detailed study has been demonstrated in literature on the microstructure evolution during temperature…”
What do you mean by “during temperature”?
- “..hardness in each case was obtained using a Rockwell hardness tester. In addition, the hardness of the samples tempered at 160 ï‚°C was tested after heating for 30 min in the range 200–500 °C using a high temperature hardness tester.”
Give manufacturer and model of the hardness tester. What was Rockwell scale?
How many indentations did you make?
SEM and TEM: give manufacturer and model of the SEM and TEM instruments.
- Page 3, line 88: “…potential polarization curve was measured at a scanning speed 88 of 1.5 mV/s in the scanning interval from −750 mV to 2500 mV.”
The correct is “potentiodynamic polarization curve”.
What were the counter-electrode and reference electrode used for the polarization tests?
How many specimens did you test?
The potentials mentioned (−750 mV to 2500 mV) are given with respect to the OCP or the reference electrode? You must specify.
- Figure 4: Figure 4d-f seems to duplicate the results shown in Figures 4a-c. It is suggested to choose only one set of figures to be displayed in the text (maybe Figure 4d-f is more appropriate).
- When you describe the microstructures shown in Fig. 8, 9 and 10, it is recommended to clearly state in what Figure the reader can find the mentioned features.
- Any comments about figures 11 and 13?
- Corrosion analysis is very in poor in manuscript. It is not possible to infer anything about the influence of Al content on the corrosion resistance of the samples based on these results. The samples are not passive, they are typically active. The reduction of current densities at potentials close to 300 mV is rather due to a thick corrosion product layer formed at high current densities and not to a protective passive film.
The utility of evaluating the corrosion properties should be reconsidered by the authors (at least with this incomplete approach).
- Discussion should be enhanced, comparing your results with relevant literature.
- Conclusions: Conclusion (4) is not supported by the data with respect to the “corrosion resistant” bearing steels.
Author Response
Dear Editor,
First of all, we would like to thank you and the reviewers of our paper (Manuscript Number: Metals-1283346) for the constructive and informative comments and suggestions. We have carefully considered the reviewers’ comments and suggestions and have modified our manuscript accordingly. The following is our detailed response to the reviewers’ comments and suggestions. For clarity, we have listed the reviewers’ comments below and have addressed them one by one.
Response to Reviewer 2 Comments
Point 1：Written language can be improved.
Response 1: Considering the reviewer’s suggestion, we carefully revised the entire manuscript and tried to avoid any grammatical or grammatical errors. In addition, we also invited several colleagues who are proficient in English paper authors to check the English, believe that this language can now be used in the review process.
Point 2: Page 2, line 49:
“However, at present time no detailed study has been demonstrated in literature on the microstructure evolution during temperature…”
What do you mean by “during temperature”?
Response 2：Thank you for your careful work. This sentence wants to express is that during the tempering process, it has been modified to “during tempering process” (see section 1, paragraph 1, line 109)
Point 3“..hardness in each case was obtained using a Rockwell hardness tester. In addition, the hardness of the samples tempered at 160 °C was tested after heating for 30 min in the range 200–500 °C using a high temperature hardness tester.”
Give manufacturer and model of the hardness tester. What was Rockwell scale?
How many indentations did you make?
SEM and TEM: give manufacturer and model of the SEM and TEM instruments.
Response 3：Considering the reviewer’s suggestion, we have added the manufacturer and model of each instrument.
The hardness tester is TIME TH-300 Rockwell hardness tester, 8 indentations are measured for each sample, and the average value is taken as the measured value
TEM experiment equipment is Japan HITACHI H-800 transmission electron microscope, SEM experiment equipment is American FEI Quanta650 scanning electron microscope. (see section 2, paragraph 3, line 193-195)
Point 4: Page 3, line 88:“…potential polarization curve was measured at a scanning speed 88 of 1.5 mV/s in the scanning interval from −750 mV to 2500 mV.”
The correct is “potentiodynamic polarization curve”.
What were the counter-electrode and reference electrode used for the polarization tests?
How many specimens did you test?
The potentials mentioned (−750 mV to 2500 mV) are given with respect to the OCP or the reference electrode? You must specify. ?
Response 4: Thank you for your careful work, the following are answer to your question about corrosion resistance.
We have modified the “potential polarization curve” to “potentialiodynamic polarization curve”. The counter-electrode is platinum electrode and the reference electrode is saturated calomel electrode(SCE). We take 8 specimens for each sample.The potentials mentioned (−750 mV to 2500 mV) are given with respect to the reference electrode. (see section 2, paragraph 3, line 200-202)
Point 5: Figure 4: Figure 4d-f seems to duplicate the results shown in Figures 4a-c. It is suggested to choose only one set of figures to be displayed in the text (maybe Figure 4d-f is more appropriate).
Response 5：Considering the reviewer’s suggestion, we have retained Figure. 4 (d-f) in the text according to your opinion, which are the revised as Figure. 4 (a-c). ( see section 3, Fig. 4)
Point 6: When you describe the microstructures shown in Fig. 8, 9 and 10, it is recommended to clearly state in what Figure the reader can find the mentioned features.
Response 6：Considering the reviewer’s suggestion, we have given a detailed description of Fig. 8, 9 and 10. Different microstructure morphologies are marked with arrows or circles in different colors, readers can clearly combine the text with the Figure for easy understanding. (see section 3, Fig. 8,9 and 10)
Point 7: Any comments about figures 11 and 13?
Response 7: Through the microstructure evolution during tempering with two different Al contents, it can be seen that the more Al content, the higher temperature which metastable ε-carbide transforms into stable cementite. The higher the transition temperature, the better tempering stability of UHCSs.
Point 8: Corrosion analysis is very in poor in manuscript. It is not possible to infer anything about the influence of Al content on the corrosion resistance of the samples based on these results. The samples are not passive, they are typically active. The reduction of current densities at potentials close to 300 mV is rather due to a thick corrosion product layer formed at high current densities and not to a protective passive film.
The utility of evaluating the corrosion properties should be reconsidered by the authors (at least with this incomplete approach).
Response 8：Considering the reviewer’s suggestion, we have re-discussed this part, we think on the basis of the existing experiments, a conclusion can be drawn that the addition of Al element improves the corrosion resistance of UHCS, and the corrosion resistance increases with the increase of Al element, even UHCS-2Al with the lowest Al content, its corrosion resistance is better than GCr15, the purpose of this experiment has been achieved. (see section 3.4)
Point 9: Discussion should be enhanced, comparing your results with relevant literature.
Response 9: Considering the reviewer’s suggestion, through literature review [24], comparing with other researcher’s results, it has confirmed the correctness of my research results. It better explains the influence of Al on carbide transformation during tempering. (see section 3.4, line 706-712)
[24] Chen, W.; Li, L.F.; Yang, W.Y; et al. Effects of Aluminum on the microstructures of transformation during slow cooling and dynamic phase transformation of undercooled austenite of hypereutectoid steel. Acta metallurgica sinica 2008, 44, 1069-1975.
Point 10: Conclusions: Conclusion (4) is not supported by the data with respect to the “corrosion resistant” bearing steels.
Response 10：Considering the reviewer’s suggestion, we have made a modification of conclusion (4), which is consistent with the experimental results. The following is the revised conclusion (4)：
Conclusion (4): The addition of Al content and the increase of addition amount can significantly inhibit the precipitation of proeutectoid network carbides in ultra-high carbon steel, so that the microstructures of UHCSs after tempering at 160℃ and 320℃ are tempered martensite and ε -carbides, which greatly improve the corrosion resistance of UHCSs, are better than GCr15, and provide a useful idea for the future development of corrosion-resistant bearing steels.
Finally, thank you for giving us a chance to revise our manuscript. Certainly, we also thank the review’s comments and suggestions. At last, we hope this revised manuscript could bring more to reader. Thank you very much.
Yours Sincerely,
Wenquan Cao,
Ph. D.
Corresponding author
College of Materials Science and Engineering,
Chongqing University,
Chongqing 400044, China
E-mail: [email protected]
Reviewer 3 Report
- English proofreading is required. For example: line 18->the transition of martensite to ferrite of martensite; line 117->microstructure are; line 163->the tempering temperature range was; line 186 ->Fig.; line 192-> did not; line 220->the number...grew; line 248->yellow arrow; line 250->white arrow; line 268->"thus..." no conjunctions
- In abstract, the effect of different Al amount on UHCSs should be addressed.
- In introduction, the effect of different Al amount on UHCSs should be reviewed. Why did the authors choose 2%, 4%, and 6% Al?
- Fig. 1, no air cooling (AC) in stage 2. Cooling means that temperature decreases.
- Only Fig. 4(d) is discussed in the text. Please add the corresponding discussion for the other Figs. 4.
- What is the hardness of GCR15 at high temperature?
- Last paragraph in page 7 is unreadable and it should be rewritten.
- In conclusion, the author stated that the hardness is 65-68HRC after quenching and tempering. Please describe the corresponding temperatures.
- What are the microstructure and hardness of UHCS without Al addition? These should be compared with the results of UHCSs with Al addition.
Author Response
Dear Editor,
First of all, we would like to thank you and the reviewers of our paper (Manuscript Number: Metals-1283346) for the constructive and informative comments and suggestions. We have carefully considered the reviewers’ comments and suggestions and have modified our manuscript accordingly. The following is our detailed response to the reviewers’ comments and suggestions. For clarity, we have listed the comments below and have addressed them one by one.
Response to Reviewer 3 Comments
Point 1: English proofreading is required. For example: line 18->the transition of martensite to ferrite of martensite; line 117->microstructure are; line 163->the tempering temperature range was; line 186 ->Fig.; line 192-> did not; line 220->the number...grew; line 248->yellow arrow; line 250->white arrow; line 268->"thus..." no conjunctions
Response 1：Considering the reviewer’s suggestion, we have improved the manuscript carefully and have the entire manuscript been edited by a colleague whose native language is English and now it should be meet the review process of the paper.
Point 2: In abstract, the effect of different Al amount on UHCSs should be addressed.
Response 2: Considering the reviewer’s suggestion, the effect of Al content on UHCS has been added to the abstract. The addition of Al element makes the ultra-high carbon steel exhibit good tempering stability, the addition of Al also effectively enhanced the corrosion resistance and the higher the Al element content, the greater the effect. (see abstract)
Point 3: In introduction, the effect of different Al amount on UHCSs should be reviewed. Why did the authors choose 2%, 4%, and 6% Al?
Response 3: Considering the reviewer’s suggestion, in the introduction part, by combining with other research results, we can see that the addition of Al element can effectively inhibit the precipitation of pre-eutectoid network carbides in UHCSs, but excessive addition will cause graphitization to occur, and is detrimental to hot formability and hot workability. In the existing research, the Al content of ultra-high carbon steel is generally selected to be 1.6%~6%. In order to study the effect of Al element in ultra-high carbon steel, the addition amount of 2%, 4%, and 6% are selected. (see introduction, line 118-123)
Point 4: Fig. 1, no air cooling (AC) in stage 2. Cooling means that temperature decreases.
Response 4: Considering the reviewer’s suggestion, the AC curve in stage 2 has been removed. (see Fig. 1)
Point 5 : Only Fig. 4(d) is discussed in the text. Please add the corresponding discussion for the other Figs. 4
Response 5: Considering the reviewer’s suggestion, we have rediscussed Fig. 4 in the original article, Fig. 4 only retained Fig. 4 (d-f), which were revised to Fig. 4 (a-c). Each figure was discussed in the article. The original Fig. 4(d) is Fig. 4(a), after cryogenic treatment in Fig. 4 (b), each high-strength steel increases in hardness due to the decrease of retained austenite. After low-temperature tempering, it can be seen from Fig.4 (c) that the hardness of the three UHCSs are all obtained after low-temperature tempering, and the hardness of UHCS-6Al steel has increased the most.
Point 6: What is the hardness of GCR15 at high temperature?
Response 6: Considering the reviewer’s suggestion, I did not do this part of the experiment, but combined with Fig. 5 and Fig. 6, it can be seen that the hardness of UHCSs are higher than GCr15 regardless of whether it is tempered or after high temperature heating. The hardness of GCr15 after high temperature tempering is no longer sufficient for the bearing conditions. (see Fig.5 and Fig.6)
Point 7: Last paragraph in page 7 is unreadable and it should be rewritten.
Response 7: Considering the reviewer’s suggestion, we have improved the manuscript carefully and have the last paragraph in page 7 been edited by a colleague whose native language is English. (see section 3.3, line 524-554)
Point 8: In conclusion, the author stated that the hardness is 65-68HRC after quenching and tempering. Please describe the corresponding temperatures.
Response 8: Considering the reviewer’s suggestion, according to Fig. 4 (a-c), UHCS-2Al, UHCS-4Al and UHCS-6Al have austenitized at 825℃, 850℃, 875℃, and at the low tempered temperature (160℃) the hardness peaks are between 65-68HRC. (see Fig.4)
Point 9：What are the microstructure and hardness of UHCS without Al addition? These should be compared with the results of UHCSs with Al addition.
Response 9: Thank you for your valuable and thoughtful comments. In this experiment, there is no Al in GCr15, and this article is also a comparison between GCr15 without Al and ultra-high strength steel with Al. There has been a lot of research on the microstructure and mechanical properties of GCr15. The quenched microstructure of GCr15 is mainly composed of spherical carbides, retained austenite and martensite [1-2]. After low temperature tempering (160℃´2h), the hardness can reach 61HRC, but the hardness decreases faster at higher tempering temperatures. The mechanical properties of ultra-high-strength steel after Al addition is better than GCr15 after tempering at higher temperature.
[1] Li, H.; Yin, T.T.; Li, Y. Effect of Deep Cryogenic Treatment on Performances of Bearing Steel GCr15. 2015, 8, 41-44.
[2] Chen, Y. Q; Wu, Y. W; Qin, Z. W; et al. Effect of treatment on microstructure and mechanical properties of GCr15 bearing steel. 2018, 42, 55-58+62
Finally, thank you for giving us a chance to revise our manuscript. Certainly, we also thank the review’s comments and suggestions. At last, we hope this revised manuscript could bring more to reader. Thank you very much.
Sincerely Yours,
Wenquan Cao,
Ph. D.
Corresponding author
College of Materials Science and Engineering,
Chongqing University,
Chongqing 400044, China
E-mail: [email protected]
Round 2
Reviewer 2 Report
The interpretation of corrosion data is not correct. The samples are typically active, not passive. There is no "stable passivation region". Current density decreased at potentials that are almost 1.0 V above the corrosion potential and reached relatively high values (in the mA scale). The samples are not passive. The influence of Al content can't be realized from the results. There is not any electrochemical parameter that indicate a reduction of the anodic dissolution rate as the Al content increased.
If consistent conclusions are to made about the corrosion behavior of the different samples, additional experiments should be conducted: electrochemical impedance spectroscopy; surface analysis of the corrosion products; weight loss measurements. Evaluation of the corrosion morphology is also highly recommended.
Based on the results shown in section 3.4, the effect of Al on the corrosion resistance of the samples is not significant and the samples are all in the active state.
Author Response
Dear Editor,
First of all, we would like to thank you and the reviewers of our paper (Manuscript Number: Metals-1283346) for the constructive and informative comments and suggestions. We have carefully considered the reviewers’ comments and suggestions and have modified our manuscript accordingly. The following is our detailed response to the reviewers’ comments and suggestions. For clarity, we have listed the reviewers’ comments below and have addressed them one by one.
Response to Reviewer 2 Comments
Point 1：The interpretation of corrosion data is not correct. The samples are typically active, not passive. There is no "stable passivation region". Current density decreased at potentials that are almost 1.0 V above the corrosion potential and reached relatively high values (in the mA scale). The samples are not passive. The influence of Al content can't be realized from the results. There is not any electrochemical parameter that indicate a reduction of the anodic dissolution rate as the Al content increased.
If consistent conclusions are to made about the corrosion behavior of the different samples, additional experiments should be conducted: electrochemical impedance spectroscopy; surface analysis of the corrosion products; weight loss measurements. Evaluation of the corrosion morphology is also highly recommended.
Based on the results shown in section 3.4, the effect of Al on the corrosion resistance of the samples is not significant and the samples are all in the active state.
Response 1: Thank you for your careful work. In order to avoid misunderstanding of readers, we have deleted the content about this part, and we will have more sufficient data to discuss the effect of Al element on the corrosion resistance of ultra-high carbon steel. Corrosion resistance is not the main focus of this article. and the related work is underway. In the future, we will write articles about this part more systematically.Finally, thank you for giving us a chance to revise our manuscript. Certainly, we also thank the review’s comments and suggestions. At last, we hope this revised manuscript could bring more to reader. Thank you very much.
Yours Sincerely,
Wenquan Cao,
Ph. D.
Corresponding author
College of Materials Science and Engineering,
Chongqing University,
Chongqing 400044, China
E-mail: [email protected]
Reviewer 3 Report
Accept.
Author Response
Dear Editor,
Thank you for your careful work of our paper (Manuscript Number: Metals-1283346) for the constructive and informative comments and suggestions, we hope this revised manuscript could bring more to reader. Finally, we wish you good health and a better career!
Sincerely Yours,
Wenquan Cao,
Ph. D.
Corresponding author
College of Materials Science and Engineering,
Chongqing University,
Chongqing 400044, China
E-mail: [email protected]
Round 3
Reviewer 2 Report
If the part dedicated to corrosion is removed from the text, I don't have any objection to its publication, if the editor agrees.
