Evaluation of the Friction Coefficient for TRIP1000 Steel under Different Conditions of Lubrication, Contact Pressure, Sliding Speed and Working Temperature
, Luiz Gustavo Souza Zamorano 2 and Rodrigo Santiago Coelho 1,*
Round 1
Reviewer 1 Report
The manuscript entitled “Evaluation of the friction coefficient for TRIP1000 steel under different conditions of lubrication, contact pressure, sliding speed and working temperature” has investigated the effects of a series of test parameters on the friction behavior of TRIP1000 steel. The manuscript has done a lot of frictional experiments and has certain engineering value. However, I have several concerns and questions that need proper attention and should be well addressed.
1. In the experiment, the author of the manuscript adopts the pin-on-Disk friction experiment, the friction time is only 60 seconds, which seems too short to represent the friction coefficient of the TRIP1000 steel. The short time of friction may also be the reason why the friction coefficient does not change significantly after the author changes a large number of experimental parameters of friction.
2. The author did not provide the type of lubricating oil and grease. The author puts forward that machine oil and grease may evaporate at 60℃,100℃, which is a far-fetched explanation.
3. It can be seen from the SEM images before and after the friction that the friction is still in the running-in stage due to the short friction time, and the sample surface roughness has a great influence on the friction coefficient. The friction coefficient at this time does not reflect the friction coefficient of TRIP1000 Steel under this series condition. For example, in figure 8 the second SEM image, scratches in both directions can be clearly seen in the picture.
4. The serial number of the subgraphs (a), (b), (c) are not indicated in most of the Figure.
5. The latest articles which are related to your content can be quoted in the appropriate place. “Tribology International 2022, 171, 107529”, “ACS Applied Materials & Interfaces 2021, 13, 55712-55725”, “Acta Materialia 2022, 232, 117934” et al.
6. There should be error bars in Figures 4 and 6.
Author Response
The answers to the questions are attached.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this paper, tribological study was made on TRIP 1000, ultra-high strength steel, using a tribo-tester with and without lubricants at room temperature and in air at 60 and 100 oC.
English language should be reexamined and some parts should be made much more readable and understandable for readers. Long sentences without comma gave me confusion.　In some sentences, it may be better to use clauses.
As for the content, I wrote my comments in attached pdf. Please see the pdf.
Comments for author File: Comments.pdf
Author Response
The answers to the questions are attached.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
[1] line 144; "the contact metal-to-metal is removed"
Does this mean "the metal-to-metal contact is reduced" ?
[2] line 162; "The adhesive wear meaning"
Does this mean "The adhesive wear" ?
[3] lines 189-195;
According to Ghiotti and Bruschi [19], the hardness of DLC and CrN-DLC coatings is about 2000HV, which is much higher than that of 304SS and 1000TRIP. They did not mention about the change in the hardness of DLC-coated 304 SS. DLC coatings as well as CrN and TiAlN coatings are very brittle, and therefore their plastic deformation with strain hardening does not occur.
On the other hand, you can find some results on friction characteristics of high-strength-steel sheets in the following references 1) and 2).
1) Evaluation of friction characteristics for high-strength-steel sheets depending conditions, Transactions of Materials Processing, 24(6). pp. 381-385 (2015). (in Korean)
2) Effects of contact pressure, sliding velocity and sliding length on friction behavior of high-strength-steel sheets, Journal of the JSTE, 54(629), pp. 537-541 (2013). (in Japanese)
In 2), similar friction behaviors with and without lubricants are shown in steels of which tensile strength ranges from 305 MPa to 1079 MPa. A part of the results obtained for the steel with the lowest strength are shown in
3) FE forming analysis with nonlinear friction coefficient model considering contact pressure, sliding velocity and sliding length, Journals of Materials Processing Technology, 227, pp. 161-168(2016).
I still think that it is preferred to refer to references in which metal-to-metal friction tests were conducted, for the comparison with your results.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
