Laser Powder Bed Fusion Processing of UNS C64200 Aluminum–Silicon–Bronze

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The exploration of the 3D printing of new materials is necessary. This article symmetrically investigates the 3D printing of aluminum silicon bronze and achieves good mechanical properties after heat treatment.

1.There are tons of research about the investigation of the 3D printing parameters, such as power, speed, hatch distance on the quality of printed parts. What is the difficulty for this bronze meterial? As mentioned in the introduction,there are several papers about bronze materials, what is the main progress of this article compared to the mentioned research works? What is the main difference of the paremeters compared to other materials such as Al, Ni, Ti alloys? 

2.hat is the main contentdifference between C64200and other similar alloys which were mentioned in the introduction? Why is new for investigation?

3. Geometry of the tensile bars? and their location in the printed parts?

4. Suggest to give the EDS results to check the distribution of elements.

5. In Fig. 18, what is the relationship between beita phase and beita prime phase?

6. In Fig.26, the cracks seem  rod like rather than crack, Why? The bigger cracks should have strong affect on ductility? It leads to the decrease of ductility.

7. The grains increases，which contributes to the decrease of ductility？

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors,
The manuscript is well written, and the introduction part is comprehensive enough to cite previous literature and link the hypothesis. The second half of the results section is excellently articulated with good details to explain the observations from relevant experiments. Some minor corrections are advised to the authors:
1. When citing an article, it is appropriate to mention the reference in chronological order. Currently it is like ABC et al. ... and no numeric link is shared for several references quoted in this manner.

2. Explain in the introduction segment how the presence of different phases, like alpha, beta-martensitic, and others, corresponds to the mechanical strengths or ductility of the system. How these phases develop and their origin in the microstructure should be presented to the understanding of all readers.

3. Explain in the text regarding your figures; for instance, Figure 2 was presented generally, and its captions (a & b) were not discussed. Which mode and what exact difference are presented by OM here, and why not BSE SEM mode instead?

4. The methodology part is lucid and neatly structured. Please mention the software utilized for DOE and statistical analysis, as shown in later figures.

5. Please elaborate on the explanation of Figure 12 from the perspective of the central composite DOE point of Figure 11; that is, how did regression analysis provide the best fit of parameters? From Figure 11, points in diagonal and vertical line from the midpoint, following the green-yellow gradient also impose suitability of processing parameters. How valid and statistically significant is the central point against the endpoints in Figure 11 (composite DOE), which demonstrated density reaching 7.7 g/cm³?

6. Please mention the reference cards with which the phases were matched in XRD. Try to refine Figure 17 in such a manner that the font size is not unclear. Highlight these alpha and martensitic phases in Figure 16. Also explain what is happening to phase transitions according to Figure 17 with heat treatment; simply presenting the figure is not enough.

7. Results section is excellently written from EBSD, IPF and BCI. A hint of explanation on microstructure refinement after LPBF as compared to wrought alloy must be discussed, as that shall translate to higher strength and hardness in the printed parts.

8. It is best to stack together as three figures for EBSD, BCI, Fracture Surface micrographs as it becomes easier to compare them instead of randomly formatted placement.

9. Besides this, I have reviewed the manuscript to be of very high quality with information and results relevant to the hypothesis, and the methodology was spot on. Following the changes requested above, I would recommend this manuscript be published in JMMP.
Good luck!

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Please give  the shapes,dimensions and scanning strategy of all the samples in fig.5a. What is the use of the samples with circle sections? And please give the photos of printed samples .
Suggest to discuss the difference of this copper alloy and other mentioned copper alloys in the introduction and what mainly makes their different printing parameters.

Author Response

Comment 1: Please give  the shapes,dimensions and scanning strategy of all the samples in fig.5a.
Response 1: Thank you for highlighting the missing detail, These have been added on Page 6 lines 178-184.

Comment 2: What is the use of the samples with circle sections?
Response 2: We appreciate the comment and see the lack of explanation, these went unused in our research and as such was left out of discussion, this has been remedied in the same addition as Comment 1.

Comment 3: And please give the photos of printed samples .
Response 3: No problem at all, a figure has been added and is now Figure 25, showing the builds.

Comment 4: Suggest to discuss the difference of this copper alloy and other mentioned copper alloys in the introduction and what mainly makes their different printing parameters.
Response 4: Thank you for the suggestion, a small addition has been made on page 3, lines 109-113. Highlighting that difference.