Fatigue Life and Residual Stress of Flat Stainless Steel Specimens Laser-Cladded with a Cobalt-Based Alloy and Postprocessed with Laser Shock Peening

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Authors investigate the influence of the laser shock peening on fatigue life of 304 stainless steel flat specimens with a cobalt-based alloy (Stellite 6) coating applied by LC. The author has done lots of work, the article is well organized and giving some new findings. But it has some problems. Some comments but not all are as follows:

1.        The abstract should be refined.

2.        There are some text errors, please check them carefully.

3.        The quality of images and charts should be improved.

4.        The authors described the influence law of postprocessed with laser shock peening to fatigue life and residual stress of flat stainless steel specimens laser cladded with a cobalt-based alloy. However, the discussion was not deep.

5.        The influence of laser shock peening on microstructures should also be discussed.

Comments on the Quality of English Language

The quality of English Language should be improved.

Author Response

Reviewer #1: Authors investigate the influence of the laser shock peening on fatigue life of 304 stainless steel flat specimens with a cobalt-based alloy (Stellite 6) coating applied by LC. The author has done lots of work, the article is well organized and giving some new findings. But it has some problems. Some comments but not all are as follows:

Comment 1: The abstract should be refined

Response: Thank you for the valuable observation. The abstract was revised.

Comment 2: There are some text errors, please check them carefully

Response: Thank you for this important observation. Errors were fixed.

Comment 3: The quality of images and charts should be improved

Response: We appreciate this valuable observation. Images were revised.

Comment 4: The authors described the influence law of postprocessed with laser shock peening to fatigue life and residual stress of flat stainless steel specimens laser cladded with a cobalt-based alloy. However, the discussion was not deep

Response: Thank you for the important observation. Discussion was improved, particularly in section 3.3

Comment 5: The influence of laser shock peening on microstructures should also be discussed

Response: Thank you for the important observation. Discussion was improved, particularly in section 3.3

Comment 6: The quality of English Language should be improved.

Response: We appreciate this valuable observation. English was revised.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Interesting manuscript with relevant data for this journal. However, some changes must be made before it can be published.

In the introduction, the question of why is stainless steel important, is left unanswered.

Line 66: “certain accuracy” avoid this type of terms, specify.

Lines 93 - 104: This should be in the Materials and Methods section.

Lines 112 - 116: The compositions would be more explicit in a table, than written in the text.

Line 115: Why was 304 stainless steel selected as the base material?

Line 129 – Argon gas purity? Specify.

Line 153: 2500 pules/cm^2 or pulses/cm^2 ? Check the units.

Figure 2 (b): The sample seems to be distorted from the laser process. Could this affect the results?

Lines 255 – 256: “This has been observed in specimens of a single material and processed with conventional manufacturing.” Specify, add references.

Line 272: “SS 304” should be mentioned in the text before calling it as short for 304 stainless steel. The first time 304 stainless steel is mentioned it should appear: “304 stainless steel (SS 304)”.

Figure 5: Scale is too small and cannot be easily perceived. (a), (b), (c) and (d) should be on top and not underneath each image.

Figure 7: Use Scientific notation for the scale in the “fatigue life axis”.

Figure 8: Scale is too small. (a), (b), (c) and (d) should be on top and not underneath each image.

Figure 9: Smal scale in (a) and (b).

Figure 10: Y and X-axis scale should be improved. The values ​​of the axes at the extremes are not obvious.

Why is Additive manufacturing mentioned in the Introduction? No connection is made throughout the extent of the manuscript. Either remove it from the introduction or make the link to it in the results and discussion and conclusions, by explaining why are the results important to it.

Figure 13 is placed after the conclusions. Should be placed near the text, right after its mentioned.

Overall, the manuscript is interesting, but the images are disorganized. They should appear in the text when mentioned. As it is, they are placed randomly. This makes it hard for a reader to analyze the data exposed in the text and compare it with the Figures.

Comments on the Quality of English Language

English is good, minor changes can be done to improove it.

Author Response

Reviewer #2: Interesting manuscript with relevant data for this journal. However, some changes must be made before it can be published.

Response. We greatly appreciate your kind comments. Your suggestions and observations have been addressed. An answer to each is given below.

• In the introduction, the question of why is stainless steel important, is left unanswered. Response: a new paragraph was added in the Introduction to address this comment.
• Line 66: “certain accuracy” avoid this type of terms, specify. Response: this term has been modified.
• Lines 93 - 104: This should be in the Materials and Methods section. Response: this information has been moved as suggested.
• Lines 112 - 116: The compositions would be more explicit in a table, than written in the text. Response: a new Table has been inserted with this information.
• Line 115: Why was 304 stainless steel selected as the base material? Response: a new paragraph was added in the Introduction to address this comment.
• Line 129 – Argon gas purity? Specify. Response: argon purity was specified in section 2.2
• Line 153: 2500 pules/cm^2 or pulses/cm^2 ? Check the units. Response: this error was fixed
• Figure 2 (b): The sample seems to be distorted from the laser process. Could this affect the results? Response: there is slight distortion in the sample after LC; however, it was left like this so as not to alter the field of residual stresses produced by this process.
• Lines 255 – 256: “This has been observed in specimens of a single material and processed with conventional manufacturing.” Specify, add references. Response: a note was added to Section 3.1 to clarify this point.
• The introduction. Line 272: “SS 304” should be mentioned in the text before calling it as short for 304 stainless steel. The first time 304 stainless steel is mentioned it should appear: “304 stainless steel (SS 304)”. Response: Abbreviation SS 304 was defined and used for the first time in the Introduction.
• Figure 5: Scale is too small and cannot be easily perceived. (a), (b), (c) and (d) should be on top and not underneath each image. Response: Image size has been enlarged and the position of legends has been moved.
• Figure 7: Use Scientific notation for the scale in the “fatigue life axis”. Response: Notation has been corrected.
• Figure 8: Scale is too small. (a), (b), (c) and (d) should be on top and not underneath each image. Response: Image size has been enlarged and the position of legends has been moved.
• Figure 9: Smal scale in (a) and (b). Response: Image size has been enlarged.
• Figure 10: Y and X-axis scale should be improved. The values ​​of the axes at the extremes are not obvious. Response: Figure was revised.
• The introduction. Why is Additive manufacturing mentioned in the Introduction? No connection is made throughout the extent of the manuscript. Either remove it from the introduction or make the link to it in the results and discussion and conclusions, by explaining why are the results important to it. Response: We are considering laser cladding as a specific additive manufacturing process, as it has been mentioned at the end of page 2.

• The introduction. Figure 13 is placed after the conclusions. Should be placed near the text, right after its mentioned. Response: This Figure was placed correctly.
• The introduction. Overall, the manuscript is interesting, but the images are disorganized. They should appear in the text when mentioned. As it is, they are placed randomly. This makes it hard for a reader to analyze the data exposed in the text and compare it with the Figures. Response: We apologize for not placing the figures properly; they have been moved in the text as suggested.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Please find my comments in the attached pdf.

Comments for author File: Comments.pdf

Author Response

Reviewer #3: The paper,. Please find my comments in the attached pdf.

Comment 1: LSP has been proven to improve fatigue life via inducing compressive residual stresses on clad coatings. Please highlight the novelty of this particular study in the Abstract.

Response: We greatly appreciate your kind comment. A note has been added to the Abstract in accordance with your suggestion.

Comment 2: Showcase the importance of laser cladding stellite on stainless steel in this Introduction section.

Response: Thank you for this important observation. A comment has been added to the Introduction in accordance with your suggestion.

Comment 3: Please specify the difference in the specimen shown in Figure 3.

Response: Thank you for this important observation. An identification has been added to each specimen.

Comment 4: The. Please tabulate the fatigue life prediction and experimental values for ease-of-understanding.

Response: Thank you for this important suggestion. A new table has been included as recommended.  

Comment 5: The. The fractography is not well studied and anlalyzed. Please refer to the publication below and improve the fracture surface analysis section of the manuscript. https://doi.org/10.1016/j.ijfatigue.2020.106135

Response: Thank you for this important observation. Section 3.3 has been improved as suggested.

Comment 6: The. The crack initiation sites highlighted in Figure 13 appears to be incorrect. Please present high magnification images of the crack initiation sites to validate the theory.

Response: Thank you for this important observation. A revision of Figure 13 has been made.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

This article can be accepted.

Comments on the Quality of English Language

The quality of English language can be better.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors addressed all my coments. The manuscript has improoved.