Wear Performance of Metal Materials Fabricated by Powder Bed Fusion: A Literature Review
Round 1
Reviewer 1 Report
Dear Authors,
The work has significantly improved from previous submission. Despite the choice of mixing polymer and metal wear makes it complex to fit everything in a single review, the text has gained in coherence with the changes.
Nevertheless, the text is still too much of a mix and it is difficult to follow where the authors are wiling to get. The choice of materials, testing techniques and assessed variables is too heterogenous to proceed with sufficient objectiveness in comparisons between papers, what gives a sensation of "compilation" rather than "review". Tribology is so material and condition dependent that makes it difficult take a clear vision of the review as a whole. It would be really helpful if this could me ammended. Despite I am aware that it is not easy given the dispersion of works in the field, it is worth a try since it will increase the visibility of the work.
Regarding specific comments:
Line 126. The explanation on the metallic powders should be improved and referenced. Please add examples of each case.
Line 137. Please explain the relevance of Figure 3 or remove it.
Figure 1, Figure 2, Figure 3, Figure 10, Figure 11, Figure 12. Quality and readability should be improved.
Figure 5. Scales are missing.
Line 210,Table 1, Line 216. Please check the names of the authors, some have typing mistakes.
Line 384. This sentence goes against Line 16 (Abstract). Please address.
I hope this helps further improve the paper.
Author Response
Responses to comments on metals-665626
We are very grateful for the valuable comments and suggestions of the reviewer.
Q1: The work has significantly improved from previous submission. Despite the choice of mixing polymer and metal wear makes it complex to fit everything in a single review, the text has gained in coherence with the changes.
Nevertheless, the text is still too much of a mix and it is difficult to follow where the authors are wiling to get. The choice of materials, testing techniques and assessed variables is too heterogenous to proceed with sufficient objectiveness in comparisons between papers, what gives a sensation of "compilation" rather than "review". Tribology is so material and condition dependent that makes it difficult take a clear vision of the review as a whole. It would be really helpful if this could me ammended. Despite I am aware that it is not easy given the dispersion of works in the field, it is worth a try since it will increase the visibility of the work.
.
Answer: Thank you for your advice. Because metal and polymer have significant differences in material properties, their friction and wear behaviors show significant differences. We re-examined the full text and found that the article was difficult to integrate metals and polymers. In order to better complete this work, we have described the friction and wear behavior of metals in this paper in more detail and accurately. At the same times we removed the polymer part. We will describe one aspect more precisely in future work.
Q2: Line 126. The explanation on the metallic powders should be improved and referenced. Please add examples of each case.
Answer: Thank you for your advice. We refer to more references to express this part more accurately. At the same times we added more examples to prove.
Q3: Line 137. Please explain the relevance of Figure 3 or remove it.
Answer: Thank you for your advice. The effect of powder size on the properties of materials is discussed. At the same time, Fig.3 is replaced by the figure of the effect of powder size on the density of the material.
Q4: Figure 2, Figure 3, Figure 10, Figure 11, Figure 12. Quality and readability should be improved.
Answer: Thank you for your advice. We changed it.
Q5: Figure 5. Scales are missing
Answer: Thank you for your advice. We changed this mistake.
Q6: Line 210, Table 1, Line 216. Please check the names of the authors, some have typing mistakes.
Answer: Thank you for your advice. We changed this mistake.
Q7: Line 384. This sentence goes against Line 16 (Abstract). Please address.
Answer: Thank you for your advice. At present, there are few studies on the friction and wear characteristics of LSed parts, but the contact conditions in the friction and wear test are more extensive.
Reviewer 2 Report
The authors have made all necessary revisions to the manuscript based on my previous comments. The content is well outlined, however, I would suggest a more logical flow in the sections of the manuscript. Moreover, the overall manuscript requires a thorough English check to enhance comprehensability.
Author Response
Responses to comments on metals-665626
We are very grateful for the valuable comments and suggestions of the reviewer.
Q1: The authors have made all necessary revisions to the manuscript based on my previous comments. The content is well outlined, however, I would suggest a more logical flow in the sections of the manuscript. Moreover, the overall manuscript requires a thorough English check to enhance comprehensability;
Answer: Thank you for your advice. Considering the readability of the article, we removed the worn part of the polymer. We also have asked two colleagues who are skilled authors of English language papers to check the manuscript.
Reviewer 3 Report
In the current manuscript “Wear performance of parts fabricated by laser sintering: a literature review” authors provided a brief review of the current progress in wear performance of alloys and composites fabricated using direct metal laser sintering. However there are major comments and manuscript cannot be considered for publication in the current version.
Manuscript is carelessly written and most parts of the manuscript need to be rewritten and rephrased to make better link between some paragraphs and sentences.Examples:
-Section 2.2, page 4, line 135-138: the authors should discuss the effect of particle size distribution and its importance in details and provide the results related to effect of particle size on properties or …. in Fig. 3 not just size distribution which has no meaning for review papers.
- Page 5, line 167-168, this paragraph is confusing and need to be rephrased. Materials and explanation pertaining to Fig. 6 is not cleared.
- Page 5, line 178-183: it should be clearly stated that whether or not the porosity is beneficial as well as advantages/disadvantages.
- Page 5, line 191-194 need to be rephrased.
- Page 5, line 186-187, “The effects of polymer sintered parts on mechanical properties, mechanical properties and processing properties were studied” does not make a sense.
- Page 12, line 294-295 need to be rephrased.
- Page 2, line 61-65, author needs to add reference(s).
- Page 2, line 95, please provide full description of CMC.
Page 2, Line 96, the sentence “Wear resistance is more dependent on application and operating conditions” is not correct. Wear resistance is mainly dependent on material properties and wear mechanism is more dependent on application and operating conditions. Table 1 missed the wear performance of materials and the wear rate need to be added to this table. If there is a high magnification image in reference 37, it would be helpful to be added to Fig.4. The word “wear” is missed in the caption of Fig. 10. Page 12, the sentence “This results in a higher hardness of the vertically constructed sample and better wear resistance under high stress, as shown in Fig.19” is not consistent with Fig. 19. All parameters in Table 2 need to be explained in text or caption. What are linear wear t1 and t2?Author Response
Responses to comments on metals-665626
We are very grateful for the valuable comments and suggestions of the reviewer.
Q1: Section 2.2, page 4, line 135-138: the authors should discuss the effect of particle size distribution and its importance in details and provide the results related to effect of particle size on properties or …. in Fig. 3 not just size distribution which has no meaning for review papers;
Answer: Thank you for your advice. The effect of powder size on the properties of materials is discussed. At the same time, Fig.3 is replaced by the figure of the effect of powder size on the density of the material.
Q2: Page 5, line 167-168, this paragraph is confusing and need to be rephrased. Materials and explanation pertaining to Fig. 6 is not cleared;
Answer: Thank you for your advice. We have rephrased this part more accurately.
Q3: Page 5, line 178-183: it should be clearly stated that whether or not the porosity is beneficial as well as advantages/disadvantages.
Answer:Thank you for your advice. The internal porosity of the part is disadvantageous. The internal porosity of the part will reduce the density of the workpiece and damage the mechanical properties of the part. The pores on the surface of the part can improve the lubrication state of the contact interface to a certain extent under lubricating conditions, which has certain advantages. We re-expressed this sentence.
Q4: Page 5, line 191-194 need to be rephrased.
Answer: Thank you for your advice. In order to better state the friction and wear behavior of laser sintered metal materials, we have removed the polymer part. At the same time, we deleted this sentence.
Q5: Page 5, line 186-187, “The effects of polymer sintered parts on mechanical properties, mechanical properties and processing properties were studied” does not make a sense.
Answer: Thank you for your advice. In order to better state the friction and wear behavior of laser sintered metal materials, we have removed the polymer part. At the same time, we deleted this sentence.
Q6: Page 12, line 294-295 need to be rephrased.
Answer: Thank you for your advice. We rephrase this sentence.
Q7: Page 2, line 61-65, author needs to add reference(s).
Answer: Thank you for your advice. We added the references.
Q8: Page 2, line 95, please provide full description of CMC.
Answer: Thank you for your advice. We describe carboxymethyl cellulose sodium salt medium viscosity (CMC) in detail.
Q9: Page 2, Line 96, the sentence “Wear resistance is more dependent on application and operating conditions” is not correct. Wear resistance is mainly dependent on material properties and wear mechanism is more dependent on application and operating conditions. Table 1 missed the wear performance of materials and the wear rate need to be added to this table. If there is a high magnification image in reference 37, it would be helpful to be added to Fig.4. The word “wear” is missed in the caption of Fig. 10. Page 12, the sentence “This results in a higher hardness of the vertically constructed sample and better wear resistance under high stress, as shown in Fig.19” is not consistent with Fig. 19. All parameters in Table 2 need to be explained in text or caption. What are linear wear t1 and t2?
Answer: Thank you for your advice. Wear resistance is mainly related to material properties, but also to the application environment. We changed this sentence. We added the wear rate of the material in Table 1. We've replaced Fig.4 with a higher resolution image. We changed the mistake in Fig.10. We removed the part of polymer.
Reviewer 4 Report
The topic of the manuscript is timely and it is worth publishing a review article. But the authors have not done justice in presenting the literature and explaining their viewpoint.
Figures are not explained and discussed with sufficient details for a reader to follow. For example, Figure 3- what do the axes represent, what does K value means should be mentioned in the manuscript.
Figure 11 is poorly discussed, SEM and EDS are not even mentioned in the manuscript.
Most figures show details that are not even talked about in the main manuscript.
Example Figure 9 - Unmelt powder?
The manuscript should be thoroughly revised and more carefully rewritten explaining the presented data.
Author Response
We are very grateful for the valuable comments and suggestions of the editors and reviewers. Our responses to all the comments are outlined below and the corresponding revisions are highlighted in grey in the revised manuscript.
Q1: Figures are not explained and discussed with sufficient details for a reader to follow. For example, Figure 3- what do the axes represent, what does K value means should be mentioned in the manuscript.
Answer: Thank you for your advice. We have explained the meaning of the coordinate system in Fig.3. The meaning of K value is also explained. Please see page 4-5.
Q2: Figure 11 is poorly discussed, SEM and EDS are not even mentioned in the manuscript.
Answer: Thank you for your advice. The meaning of the SEM and EDS data in Fig.11 is explained in detail. Please see page 10.
Q3: Most figures show details that are not even talked about in the main manuscript.
Example Figure 9 - Unmelt powder?
Answer: Thank you for your advice. We have described the data presented in this article in more detail, including Figures 7, 8, 9, 14, 16, and 17. The unmelted powder in Figure 9 is to show that the single-component iron will cause pores in the material due to the appearance of unmelted powder particles during sintering. The uniform distribution of SiC in the material can improve the density of the material to a certain extent.
Reviewer 5 Report
This article presents review of wear resistant alloys fabricated by Selective Laser Sintering method. Authors listed groups of material and mainly described results of dry wear tests of them. The paper is written in logical way and quite good in English. However some of wear resistant AM alloys were omitted, e.g. cobalt based materials. Some of presented documentation is not representative (e.g. microstructure of titanium alloys produced by SLS technique and conventional way is similar both variants are characterized by α’ phase - moreover the magnification for both SEM images is different) and quality is too low (e.g. what does Fig.4a present?). The SLS is well-known process – section titled Laser Sintering is not needed any more. Besides nowadays SLS machines are equipped with fiber laser. You should also used full name of process – Laser Sintering is simplified name. The labeling of the samples must be clearly defined (e.g. what do VB, HT1-VB, HT2-VB mean?). Please carefully check Table 1 - there is some mistakes such as Laser Powder, Contact pressure given in N, slice thickness, etc. Finally the title of this review does not reflect the paper content – what metal parts were tested?
It is worth also mentioned that SLS methods belong to less attractive additive technology processes (especially for metal parts) than Selective Laser Melting. Due to the work scientific impact can be considered as medium.
Author Response
We are very grateful for the valuable comments and suggestions of the editors and reviewers. Our responses to all the comments are outlined below and the corresponding revisions are highlighted in grey in the revised manuscript.
Q1: Some of wear resistant AM alloys were omitted, e.g. cobalt based materials.
Answer: Thank you for your advice. Cobalt-based materials are widely used wear-resistant materials. However, more attention is currently being paid to the mechanical properties and shape structure of direct metal laser sintered cobalt-based alloys. At the same time, the tribological properties of the material are closely related to the contact environment. So we did not introduce these materials in the paper.
Q2: Some of presented documentation is not representative (e.g. microstructure of titanium alloys produced by SLS technique and conventional way is similar both variants are characterized by α’ phase - moreover the magnification for both SEM images is different) and quality is too low (e.g. what does Fig.4a present?).
Answer: Thank you for your advice. We compared the microstructures of Ti6Al4V made using DMLS and traditional processes (wrough). The study found that Ti6Al4V alloy with DMLSed exhibits finer acicular α´-martensite phase. The wrough Ti-6Al-4V shows an equiaxed α/β mixture and some coarse, acicular α phases. Please see page 5. We replaced them with higher quality pictures.
Q3: The SLS is well-known process – section titled Laser Sintering is not needed any more. Besides nowadays SLS machines are equipped with fiber laser. You should also used full name of process – Laser Sintering is simplified name.
Answer: Thank you for your advice. We have modified the expression of laser sintering in the paper.
Q4: The labeling of the samples must be clearly defined (e.g. what do VB, HT1-VB, HT2-VB mean?). Please carefully check Table 1 - there is some mistakes such as Laser Powder, Contact pressure given in N, slice thickness, etc.
Answer: Thank you for your advice. We have described these brief descriptions in more detail, such as VB (vertical built), HB (horizontal built), HT (heat treatment). Please see page 14. We changed this error to replace contact stress with load and slice thickness with layer thickness. Please see page 7-8.
Q5: The title of this review does not reflect the paper content – what metal parts were tested?
Answer: Thank you for your advice. We changed the title to replace metal parts with metal materials.
Round 2
Reviewer 1 Report
Dear authors,
Thanks for taking into account my comments.
Regards,
Author Response
We are very grateful to the reviewer for your valuable comments and suggestions that allowed us to better improve the content of the article.
Reviewer 4 Report
The revised manuscript can be published.
Author Response
Thank you very much for your kindly editing and giving us the opportunity to revise it. We also deeply appreciate the great efforts and valuable comments of the reviewers about the manuscript. Their efforts and insights are a tremendous help to us during this revision.
Reviewer 5 Report
The article has been improved but some of suggested corrections have been omitted, i.e.:
Figure 4a still requires correction – the microstructure of 316L fabricated by conventional process is not visible !!! Please carefully check Table 1 again – what does “Laser powder” given in Watts mean?? In my opinion “Compare to traditional process” column does not make sense. Only one variant has been compared. Moreover should be "Comparison..." instead of "Compare...". The quality of Figure 17 (especially EDS spectra) must be strongly improved.Additionally I have a problem with SLM and DMLS – you use these acronyms synonymously. Generally samples were fabricated by Selective Laser Sintering. Direct Metal Laser Sintering name is used by EOS company. Are you sure that materials that are described as DMLS-ed samples were produced with EOS machines?
Please check also Keywords – additive manufacturing and 3D printing mean the same. First of all there is the lack of "Selective Laser Sintering" and "wear resistant materials" keywords.
Author Response
Responses to comments on metals-665626
We are very grateful for the valuable comments and suggestions of the reviewers. Our responses to all the comments are outlined below and the corresponding revisions are highlighted in grey in the revised manuscript.
Reviewer#1:
Q1: Figure 4a still requires correction – the microstructure of 316L fabricated by conventional process is not visible.
Answer: Thank you for your advice. Since no clearer picture was found in the paper, we re-contrast the microstructure of cast and direct metal sintered AlSi10Mg. Please see page 6.
Q2: Please carefully check Table 1 again – what does “Laser powder” given in Watts mean?? In my opinion “Compare to traditional process” column does not make sense. Only one variant has been compared. Moreover should be "Comparison..." instead of "Compare...". The quality of Figure 17 (especially EDS spectra) must be strongly improved.
Answer: Thank you for your advice. We changed Laser powder to laser power. We removed the comparison of wear between direct metal sintered materials and traditional process materials. Since no higher quality pictures are found in the reference, we delete Fig.17.
Q3: Additionally I have a problem with SLM and DMLS – you use these acronyms synonymously. Generally samples were fabricated by Selective Laser Sintering. Direct Metal Laser Sintering name is used by EOS company. Are you sure that materials that are described as DMLS-ed samples were produced with EOS machines?
Answer: Thank you for your advice. We are sure that materials that are described as DMLS-ed samples were produced with EOS machines.
Q4: Please check also Keywords – additive manufacturing and 3D printing mean the same. First of all there is the lack of "Selective Laser Sintering" and "wear resistant materials" keywords.
Answer: Thank you for your advice. We replaced 3D printing with Powder Bed Fusion and added wear resistant materials.
.
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
Dear authors,
Summary: the paper reviews the wear behavior of laser sintered parts.
General comments: the review is well written and the explanations are clear. Nevertheless, it would require more depth and focus in the subject which is reviewed.
Being the title related to metal parts, the text also refers to polymer wear, what is misleading.
Despite wear is a broad discipline and LS technology allows facing the different mechanisms employing different metallurgical approaches, no discussion is presented regarding these points.
Wear testing technique, conditions and the tribopairs are major factors in the results. No details is given for comparison.
The information ordering is not clear, it is difficult to get an overall image of the reviewed field.
Regarding the reference collection of the review, it is surprising that there is few references to journals specialized in tribology and wear. Fixing this aspect would greatly help increase the soundness of the review.
Specific comments:
Line 23. Rephrasing the last two sentences could help readability.
Line 32. The sentence is misleading, WAAM, LMD, EBM are omitted despite they are relevant technologies in the field.
Line 36. Where it says "Additives" should say "Additive".
Line 40. Hot Isostatic Pressing should be mentioned provided the relevance of the technique for to ensure low porosity in SLS and DMLS parts.
Line 45. Please explain what is meant by "pre-diffused".
Line 48. A reference seems to be missing.
Line 50 Watts should be in capital letter.
Line 52. Please explain what is meant by "Baidu".
Line 64. More general references would fit better than the selected ones.
Line 75. The sentence "On the other..." is hard ot defend. Stronger arguments are required for such an affirmation or the specific cases should be mentioned. Remember e.g. porous copper bushing that take advantage from lubrication to show a better wear performance than fully dense alternatives with the same material.
Line 87. Sintering impplies that no melting of the powder happens (except for Liquid Phase Sintering). The sentence is misleading and doesn't fit with the materials that are mentioned (they are Solid Phase Sintered).
Line 93. A comment on the evolution of blue laser for copper laser sintering would be appropriate in this point.
Line 100. It is not clear why polymers are introduced. A polymer-metal mixture fits, but then ceramic-metal mixtures, which are very relevant in the field of wear resistance should be mentioned too.
Line 102. The sentence is only true for a set of sintering strategies. Can not be presented as general rule.
Line 103. Wrong units.
Line 108. A size distribution curve would fit better than a SEM image.
Line 115. Where it says "machining" it should say "machine".
Line 127. Where it says "traditional methods" the sentence should be more specific since it is not true for all cases.
Line 128. The equaxiality may not be true in all cases (e.g. wear against cold rolled bands).
Line 133. Defect description is rather general and their influence in wear behavior is important. This can be improved.
Line 142. Polymer don't fit with the title.
Line 168. Referencing style is not kept homogeneous across the paper.
Line 176. Despite Ti is a BCC Stabilizer, if it is bound to C this effect disappears.
Line 183. "highe r"
Line 188. The comparison of reinforced vs. non reinforced iron doesn't apply.
Figure 9. Except for LPS, the powder should not melt during SLS or DMLS.
Line 212. TiB2 is used for grain refinement. How does it interact with the wear and a hardening particle?
Line 233. Higher hardness doesn't always mean a better wear behavior. This should be supported by testing.
Line 236. "Studied" appears twice.
Line 240. Three body wear is a complex process, some more insight would be required to support the sentence.
Line 241. The sentence on the effect of HT should be supported with a reference.
Line 248. Polymers just don't fit.
Line 352. It is said earlier in the review that there are few works on SLS DMLS, the sentence affirms the other way round "has been extensively studied".
I would like to encourage you to go over the review and submit it after rework. The paper currently seems to be a good start, but requires further improvement to achieve an attractive impact.
Regards.
Reviewer 2 Report
Please find my comments in the attached pdf file.
Comments for author File: 
Comments.pdf
