Effect of Thermal Fatigue on Microstructure and Mechanical Properties of H13 Tool Steel Processed by Selective Laser Surface Melting
Round 1
Reviewer 1 Report
1. Please elaborate on how we can use data since
"The thermal fatigue crack was not observed on each specimen surface after 1200 thermal cycles."
2. Figure 12 shows Finite Element results (von Mises stress contours). If this numerical analysis is considered an important component of this paper, more details are necessary.
Author Response
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Reviewer 2 Report
the Conclusion part can be improved.
Author Response
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Reviewer 3 Report
The authors investigated the relationship between mechanical properties and thermal fatigue behavior of materials processed by selective laser surface melting. Tensile properties at room temperature and elevated temperature of treated specimens and untreated specimens were compared after different thermal fatigue cycles. According to the authors the microhardness in the laser-melted zone gradually declines with increasing thermal fatigue cycles. At room temperature as well as at elevated temperature the strength of the specimens gradually decreases while the fracture elongation gradually increases with an increase in thermal fatigue cycles. Their microstructural examinations revealed that the grain size in the laser-melted zone is insensitive to thermal fatigue cycles. The percentage of LAGBs decreases with increasing number of thermal fatigue cycles. The finite element method was used to analyze the stress distribution on the specimen surface during tensile load with the result that stress transfer exists between laser-affected and untreated zone.
The authors present some interesting results and conclusions but sometimes it is not clear how they come to the conclusions and there still remain some open questions:
Figure 1: The image of the living prototype is not necessary because it is well known. In addition a magnification bar and a citation is missing. So, either remove the figure or add magnification or citation.
Figure 2: Inscription is too small.
Line 124 127: Are these statements supported by your results? In the microstructure (figure 4) no martensite is visible.
Figure 3: It would be better to use the same y-axis and add the height of the maximum peak. Otherwise the reduction of the peak intensity is difficult to see.
Figure 4 and related text: It would be better to use the same, and if possible a higher, magnification for figures 4 b-d. In the current figure some features of the microstructure are not visible and difficult to compare.
Figure 5 and related text: How can you be sure, that microstructural refinement and the formation of martensite in the laser-melted zone result in hardness increase? Can you show the martensite? What about precipitation hardening?
Figure 6 and related text: It would be better to use a higher magnification for figures 6 a-d because differences are difficult to see.
Figure 7 and related text: The magnification is much too small to see details. A representative section of the mapping would be better. Magnification and step size are not readable. The colour coding in 7b and 7d is missing. In 7e the two different bars are not distinguishable. Fewer grain size classes would be better.
Figure 12 and related text: The colour coding of the stress is not readable. In addition the maximum levels are different, thus, the two images are not comparable.
Conclusion: The conclusion does not adequately describe the content of the paper.
References to related work are given.
The English is poor and needs major revision.
Author Response
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Reviewer 4 Report
Review for metals-535404
Effect of Thermal Fatigue on Microstructure and Mechanical properties of H13 Tool Steel Processed by Selective Laser Surface Melting
The authors address an interesting research topic for the journal Metals. It is a rigorous and well-organized paper. Only one comment: Although the number and the selection of references is adequate, it would be advisable to include some papers from the journals of MDPI editorial (Metals, Coatings, Applied Sciences, Materials, etc.) related to the topic of the manuscript.
Author Response
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Round 2
Reviewer 3 Report
The authors present some interesting results and conclusions but despite some corrections there still remain some open questions:
Figure 1: is improved
Figure 2: Inscription is improved.
Line 124 127: section is rewritten
Figure 3: is improved
Figure 4 and related text: The authors did not want to use higher, magnification for figures 4 b-d. Some features of the microstructure are still not visible and difficult to compare but I can accept their point of view that it will be sufficient.
Figure 5 and related text: related text is improved
Figure 6 and related text: The authors did not want to use higher, magnification but I can accept their point of view that it will be sufficient.
Figure 7 and related text: The magnification is still much too small to see details. Please use only a representative section of the mapping.
Magnification is now readable but the step size is now missing.
7e is a little better now.
But the authors mixed the figures with respect to the former version: a) is now c)
Thus, the magnification is much too small to see anything!
Figure 12 and related text: The colour coding of the stress is improved.
I know, that the stress distributions are different. But you can adjust the colour coding to the same stress classes, for making the two images comparable. E.g. the red parts in the lower figure have to be orange.
Conclusion: The conclusion is still not a conclusion. A conclusion contains answers to the questions: - What was the intention?, - what has been done?, - what are the results?
References to related work are given.
The English is much better.
Author Response
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Author Response File: Author Response.pdf
Round 3
Reviewer 3 Report
All required improvements have been done.
Minor linguistic corrections of the conclusion are necessary.
Author Response
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Author Response File: Author Response.pdf
