The Method of Calculating Ploughshares Durability in Agricultural Machines Verified on Plasma-Hardened Parts
Round 1
Reviewer 1 Report
This paper developed a method for calculating the durability of a ploughshare for various types of soils. The tests of plasma hardening 65G-steel ploughshare confirmed the validity of the proposed methodology for predicting the durability of the tools of soil-cutting agricultural machines. This paper is useful to predict the service life of soil-cutting agricultural machines, and should be published after minor revision.
1. It is suggested to describe more clearly how to get the equations in the proposed model, since it is the most important contribution of this paper. It is not clear for me whether some of the empirical formulas are adopted from references or derived based on some assumptions in this paper. For example, are equations (10)(11) from references? What is the meaning of the numbers in the first brackets in these two equations?
2. It is suggested to modify Figure 3 to show the hardness values more clearly, instead of showing too much useless background.
3. There is no Figure 1.
Author Response
Dear Reviewer,
Thank you very much for taking the time to read our manuscript thoroughly and make recommendations for its correction and improvement. We have read the comments carefully and have responded to all your comments.
Remark 1
It is suggested to describe more clearly how to get the equations in the proposed model, since it is the most important contribution of this paper. It is not clear for me whether some of the empirical formulas are adopted from references or derived based on some assumptions in this paper. For example, are equations (10)(11) from references? What is the meaning of the numbers in the first brackets in these two equations?
Answer
Empirical dependencies 10 and 11 are taken from works 19 and 67. The dependencies were first mentioned in 1969 and are still used (authors 18,19,67) to calculate the total pressures acting on the toe and blade of the plowshare2.
Remark 2
It is suggested to modify Figure 3 to show the hardness values more clearly, instead of showing too much useless background.
Answer
The drawings were modified
Remark 3
There is no Figure 1.
Answer
This is a typo, the description has been corrected.
Reviewer 2 Report
The article “The Method of Calculating Ploughshares Durability in Agricultural Machines Verified on Plasma Hardened Parts” is devoted to a problem that can be generally formulated as an increase of parts and instruments wear resistance. Even taking into account the abundance of proposed methods and technologies that can increase the service life of various parts and tools, this task is still relevant.
There are a number of significant comments to the article that require paper major revision:
1. The introduction is not balanced. Much attention is paid to the role of MTU in increasing yields, reliability of tractor units, accounting for economic losses, etc. While the article is devoted to a specific processing technology (plasma hardening) and a specific method for calculating the service life. In this regard, part of the introduction should be devoted to an overview of modern surface hardening technologies and service life assessment methods. Several papers on this topic are only mentioned in the paper, and there is no analysis of them. In this regard, it is difficult to estimate a novelty of the service life assessment methodology used by the authors.
2. The paragraph (lines 151-154) is formulated not quite correctly from the point of view of materials science. For example, if we recall Hadfield steels, then the statement of the authors that manganese does not have a positive effect on the steels wear resistance looks very controversial. And the influence of alloying elements on the properties of complexly alloyed steels is determined not only by the presence of specific alloying elements, but also by their content and the nature of the interaction of these elements with iron, carbon and with each other.
3. The information in lines 248-250 looks unusually. Why are serial ploughshares made of 65G steel not subjected to any hardening technologies, if it is known in advance that they operate for wear?
4. The confirmation of the information presented in lines 270-272 is required, that the main reason for the limitation on the thickness of the hardened layer (1.0...1.8 mm) is a decrease in the tribotechnical characteristics.
5. The four photos showing the hardness test procedure (Figure 3) seem redundant. Either one or not at all is enough.
6. It is not clear why the photos of microstructures are presented in the paper (Figure 4). It is approximately clear what is depicted on them, but it is not clear what the authors wanted to explain, since there are no comments on these structures.
7. Table 4 should be shortened. Instead of 20 measurements, it is enough to specify the mean value and variance (or range of values). There is also an error - most likely, the HRC hardness values are indicated in the table, because such low Brinell hardness values cannot be obtained on the material under study. If these are still HRC hardness values, then it should be taken into account that the device allows reliable measurements only in the range of 20...70 HRC.
8. It is not indicated whether surface preparation was carried out before hardness measurements? What was the thickness of the part being measured? These parameters can greatly affect the accuracy of hardness measurements with this device.
9. After reading the entire article, there is no understanding of the relationship between service life calculation (Section 2) and plasma hardening results (Sections 3 and 4). If we are talking about the fact that according to the increased value of hardness, determined experimentally, the service life was calculated, and it increased (according to calculations) by 2...3 times, then such a conclusion requires proof in practice.
Based on the conclusions, it turns out that the hardness has increased by 2-3 times (line 372-373), which means that the service life has increased by 2-3 times (line 390). Is this the whole conclusion?
Minor errors noticed during the review:
1. Abstract (line 10): In the first sentence, the word “reliability” appears twice (obviously, in different meanings).
2. The sentence (lines 290-291) is obviously missing a word.
3. The sentence (lines 356-358) is misspelled.
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The article needs to be revised in accordance with the comments.
Author Response
Dear Reviewer,
Thank you very much for taking the time to read our manuscript thoroughly and make recommendations for its correction and improvement. We have read the comments carefully and have responded to all your comments.
Remark 1
The introduction is not balanced. Much attention is paid to the role of MTU in increasing yields, reliability of tractor units, accounting for economic losses, etc. While the article is devoted to a specific processing technology (plasma hardening) and a specific method for calculating the service life. In this regard, part of the introduction should be devoted to an overview of modern surface hardening technologies and service life assessment methods. Several papers on this topic are only mentioned in the paper, and there is no analysis of them. In this regard, it is difficult to estimate a novelty of the service life assessment methodology used by the authors.
Answer
The article has been supplemented and revised lines 61-110. The introduction is structured into 3 key sections: relevance, durability calculation method and plasma hardening method. The shortcomings of existing methods and methods of hardening are listed, the relevance of the presented methodology for calculating durability and the method of plasma hardening is substantiated.
Remark 2
The paragraph (lines 151-154) is formulated not quite correctly from the point of view of materials science. For example, if we recall Hadfield steels, then the statement of the authors that manganese does not have a positive effect on the steels wear resistance looks very controversial. And the influence of alloying elements on the properties of complexly alloyed steels is determined not only by the presence of specific alloying elements, but also by their content and the nature of the interaction of these elements with iron, carbon and with each other.
Answer
Thank you for your attention. We agree. We have made some corrections in the text
Remark 3
The information in lines 248-250 looks unusually. Why are serial ploughshares made of 65G steel not subjected to any hardening technologies, if it is known in advance that they operate for wear?
Anser
When the part is hardened, it will lose its flexibility and ductility, chips and chipping will appear. Various surfacing and spraying are used, but they make the part thicker and increase the load on the machine. The article is supplemented.
Remark 4
The confirmation of the information presented in lines 270-272 is required, that the main reason for the limitation on the thickness of the hardened layer (1.0...1.8 mm) is a decrease in the tribotechnical characteristics.
Answer
The article is supplemented. Since only the friction surface is subject to wear, while, as mentioned above, hardening of the entire part or an unreasonable increase in the thickness of the hardened layer will increase the brittleness of the part, in addition, this is not economically feasible. The depth of the hardened layer turned out to be sufficient; this was confirmed by field tests.
Remark 5
The four photos showing the hardness test procedure (Figure 3) seem redundant. Either one or not at all is enough.
Answer
It was corrected in the article
Remark 6
It is not clear why the photos of microstructures are presented in the paper (Figure 4). It is approximately clear what is depicted on them, but it is not clear what the authors wanted to explain, since there are no comments on these structures.
Answer
We have added explanations from our previous work to the article
- Kanaev, A. T.; Gulyarenko, A. A.; Sarsembaeva, T. E.; Ayazbaeva, A. B. Structure Formation under Plasma-Assisted Hardening of Thin-Walled Low-Weight Parts. Steel in Translation 2021, 51 (8), 582–586. https://doi.org/10.3103/s0967091221080064
Remark 7
Table 4 should be shortened. Instead of 20 measurements, it is enough to specify the mean value and variance (or range of values). There is also an error - most likely, the HRC hardness values are indicated in the table, because such low Brinell hardness values cannot be obtained on the material under study. If these are still HRC hardness values, then it should be taken into account that the device allows reliable measurements only in the range of 20...70 HRC.
Answer
Agree with the reviewer, the values are indeed indicated on the HRC scale, a typo has been corrected. The table was corrected
Remark 8
It is not indicated whether surface preparation was carried out before hardness measurements? What was the thickness of the part being measured? These parameters can greatly affect the accuracy of hardness measurements with this device.
Answer
The article was supplemented with lines 379-382: “Pre-treatment of the surface after hardening before ultrasonic hardness testing was not carried out, since with the correct choice of the hardening mode, there is no surface damage. At the same time, the thickness of the plow share in the section was 8-12 mm.) In addition, having obtained such This remark became interesting to us and we carried out additional measurements on thick (10-30 mm) and thin parts 1-2 mm, which show that the thickness of the part does not affect the readings of the ultrasonic hardness tester.”
Remark 9
After reading the entire article, there is no understanding of the relationship between service life calculation (Section 2) and plasma hardening results (Sections 3 and 4). If we are talking about the fact that according to the increased value of hardness, determined experimentally, the service life was calculated, and it increased (according to calculations) by 2...3 times, then such a conclusion requires proof in practice.
Based on the conclusions, it turns out that the hardness has increased by 2-3 times (line 372-373), which means that the service life has increased by 2-3 times (line 390). Is this the whole conclusion?
Answer
Yes, indeed, this is the conclusion of the study, and this is quite enough given the low cost and the possibility of hardening practically in the field. This is confirmed by the results of the 1st season of using hardened plows on 2 agricultural enterprises, the operating time was 20 hectares, these are primary data that only confirm the correctness of the calculations, while field trials are still ongoing and the results of comparing the actual durability of nominal and hardened plows will also be published , but this is a lot of work, the volume of the publication will not allow adding the results of measurements of changes in the geometry of the shares, depending on the operating time. This topic will be extended in the next publications.
Remark 10
Minor errors noticed during the review:
Answer
All the minor errors have been corrected.
Round 2
Reviewer 2 Report
Article “The Method of Calculating Ploughshares Durability in Agricultural Machines Verified on Plasma Hardened Parts”. Review of the revised version.
The authors took into account all the comments that were given in the previous review. At the same time, some issues require additional explanations and comments:
The description of the microstructure in Figure 4 is well done, but there is no designations (captions) of the structures (martensite, trostite, sorbite, etc.) in the figures. It is also hard to believe that in the initial state of 65G steel, the amount of ferrite and pearlite is about 50% each (line 408). The share of pearlite should be much higher, as confirmed by Figure 4a. Also, the scale bars in Figure 4 are in Russian – they should be translated into English.
Minor errors:
• Title of section 2: “methodes” to be replaced by “methods”. In general, there are misprints and errors in the text.
• In Table 4, the second column – “…HRC to hardening…” should be replaced by “…HRC before hardening…”.
• Year of last revision of GOST 14959 is 2016 (not 2009).
• The authors write that no additional surface preparation was carried out before the hardness measurement (line 376). At the same time, the instruction for the hardness tester UZIT-3 gives unambiguous recommendations for surface roughness (Ra). I hope this did not affect the accuracy of the measurements.
• It is necessary to specify the title of section 2.2.
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Author Response
Dear Reviewer
Thank you once again for all the comments and suggestions. We did our best to implement all the suggested changes.
Remark 1
The description of the microstructure in Figure 4 is well done, but there is no designations (captions) of the structures (martensite, trostite, sorbite, etc.) in the figures. It is also hard to believe that in the initial state of 65G steel, the amount of ferrite and pearlite is about 50% each (line 408). The share of pearlite should be much higher, as confirmed by Figure 4a. Also, the scale bars in Figure 4 are in Russian – they should be translated into English.
Answer
The signatures of the structures are added to the figure, and the scales are also translated into English. We agree with the remark that in Figure 4a the proportion of pearlite looks larger, but this is at a magnification of 50x, if you look at the same structure in Figure 4c (that is, at a magnification of 10x) then it is 50-50. Perhaps, when zoomed in, I came across an area with a larger proportion of pearlite, but in general, most of the photographs indicate that this is about 50-50 ferrite and pearlite. Minor errors:
Remark 2
Title of section 2: “methodes” to be replaced by “methods”. In general, there are misprints and errors in the text.
Answer
It was corrected in the text.
Remark 3
In Table 4, the second column – “…HRC to hardening…” should be replaced by “…HRC before hardening…”.
Answer
It was corrected in the text.
Remark 4
Year of last revision of GOST 14959 is 2016 (not 2009).
Answer
It was corrected in the text.
Remark 5
The authors write that no additional surface preparation was carried out before the hardness measurement (line 376). At the same time, the instruction for the hardness tester UZIT-3 gives unambiguous recommendations for surface roughness (Ra). I hope this did not affect the accuracy of the measurements.
Answer
We agree with the remark, we also thought so and repeated the experiment many times on different surfaces, including processed ones, while the average readings are identical. In addition, it was found that plasma hardening changes the surface roughness very slightly, and even if both surfaces on the same part are ground after hardening, the hardness indicators after grinding practically do not change. We are confident that the influence of this factor is insignificant in our case, since the roughness of the samples within the specified limits and among themselves is almost identical.
Remark 6
It is necessary to specify the title of section 2.2.
Answer
It was corrected in the text.
