Effect of Cyclic Loading on the Surface Microstructure Evolution in the Pearlitic Rail
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript with a title “Effect of Cyclic Loading on the Surface Microstructure Evolution in the Pearlitic Rail” presents a study on the effects of cyclic loading on the surface microstructure evolution of different contact locations in a used pearlitic rail. The authors used SEM and EBSD to examine the microstructures of different contact locations on a used rail. They also calculated the wheel-rail contact probabilities and forces by using the rail profiles. The authors found that cDRX occurred in the wear and RCF regions during cycling rolling contact loading, resulting in ultra-fine grains with more HAGBs, lower KAM values, and more REX. The authors, also observed that the grain orientations along [111] parallel to the vertical direction were influenced by the normal force in the wear region, while grains in the RCF region were non-oriented. The topic is relevant and important.
However, the manuscript also has some limitations and weaknesses that need to be addressed and improved. Here are some specific recommendations and suggestions for each section of the manuscript:
Abstract
1. The abstract could be improved by adding a quantitative summary of the main findings.
Introduction
2. The references may not reflect the most recent developments and findings in the field of rail materials and engineering. Therefore, it may be advisable to update some of the references with newer ones, if possible.
3. The main research question from the aims section in the introduction, is not explicitly stated. The authors do not formulate a clear and concise question that guides their research.
Materials and Methods
4. The authors could provide more information on how they conducted the dynamic simulation.
5. The authors could provide some references to support their choice of methods.
6. The authors should check the numbering of “Figure 43.1”.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsRemarks: There are a number of comments about the article:
1) In the “Abstract” section, we can recommend deciphering the abbreviations KAM and REX.
2) The correct term is “Inverse pole figure”, not “Inverse polar figure”.
3) The statement on page 2 in lines 47-46 “the presence of a dominant crystallographic orientation can significantly slow down the formation and spread of fatigue cracks” is not entirely correct and justified. It's better to remove it. In particular, the <111> orientation is the direction with the minimum Schmid factor and maximum elastic modulus, but how this will affect fatigue crack growth rates requires separate studies.
4) The texture, even under tension, never coincides with the Burgers vector ½<111> (Section 2.3., p. 6), since several shear systems are always in effect, which give a compromise resulting orientation; during compression (wear), the reorientation of the lattice is carried out by rotating the normal to sliding plane towards the compression axis.
5) The EBSD method, with all its advantages, has a significant drawback in relation to the X-ray method of texture measurement, namely significantly lower statistical reliability, therefore in the future it is desirable to supplement the data from EBSD with OPF obtained by the X-ray method.
6) Future authors may also be encouraged to consider using texture data, given its unique sensitivity to the technological history of the rail material. These data can provide results no less important than the interpretation of structural changes in different areas of the rail.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsPaper No.: coatings-2614161
Title: Effect of Cyclic Loading on the Surface Microstructure Evolution in the Pearlitic Rail
The subject and the experimental results are good; however, the numerical and analytical calculation and results are unclear. The calculation and simulation steps and parameters should be clear to the extent that it can be reproduceable by the reader.
Abstract
1- Please use defined abbreviations in the abstract “KAM , and REX”.
Introduction
2- Can SEM equipped with Electron Backscatter Diffraction (EBSD) investigate dislocations in materials? Please revise.
3- Please change “Crystal grains” into “grains”.
4- “It is worth noting that the presence of a dominant crystallographic orientation can significantly slow down the formation and spread of fatigue cracks”. Please revise this statement. In the preceding lines you have mentioned: “It is reported that a dominant {110} crystallographic texture near the rail surface could inhibit crack formation and enhance wear resistance”. It means that no any dominant crystallographic planes can help resisting fatigue crack.
5- In line 62, the authors are talking about the obtained results. At this situation the authors are usually presenting the aim of the work.
Materials and Methods
6- Figure 1.b is not clear for the reader. In Fig. 1.c it is clear that the samples 1, 2 and 3 were cut from the side, corner and top of the rail head; respectively. These are not clear on Fig. 1.b.
7- The sample is taken from a curved segment of the rail road, which make the study just applied for certain this form of curved rails. It was better if additional samples from straight rail have been investigated.
8- In lines 68-70 the authors have mentioned the cause of fatigue cracking before starting the investigation, which is unusual.
9- Please reword “we” in line 70 the third person.
10- Are the chemical compositions and mechanical properties in Table 1 experimentally tested by the authors or taken from literature? If taken from literature, please mention the reference.
11- Eq 1 & 2 need references.
12- “Additionally, the lateral and vertical forces for samples 1#, 2#, and 3# were calculated using dynamic simulation, based on the rail's actual tested profile data”. Please mention the details of simulation (idealization, calculation and the results).
13- Please mention the values of the whole used parameters in eq 1&2. The calculation and simulation processes and parameters should be clear to the extent that it can be reproduceable by the reader.
Results
14- What is given limit to the SEM to differentiate between HAGB and LAGB.
15- Please explain to the reader what is the significance of the Kernel Average Misorientation (KAM)?
16- In Figs. 2 & 3, I suggest to add a column to the right side containing 1#, 2# and 3#.
The calculations of the results of the last three figures are unclear.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsAccept in present form
Author Response
Thanks for your comments and suggestions.
Reviewer 3 Report
Comments and Suggestions for AuthorsPlease present a table containing the values of the parameters used in calculation of the results in Table 3. and Fig. 6.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
