Microstructural Development of Ti-6Al-4V Alloy via Powder Metallurgy and Laser Powder Bed Fusion
, Heike Ebendorff-Heidepriem 3 and Reza Ghomashchi 1,3Round 1
Reviewer 1 Report
This paper studied the microstructural differences between Ti-6Al-4V parts fabricated via the conventional powder metallurgy (PM) and the laser powder bed fusion. The author found that microhardness of L-PBF processed Ti6Al4V samples is remarkably higher than that of the PM samples, and the reason was discussed. This paper can be accepted after minor revision.
1. The “selective laser melting” in the keywords should be deleted, because it has the same mean with laser powder bed fusion.
2. In abstract, the author mentioned that with a large concentration of low angle boundaries of α′, but the evidence of low angle boundaries of α′ should be provided.
Author Response
We would like to convey our appreciations to both the editor and reviewers of our manuscript and the opportunity to enhance the quality of the article. We have carefully revised the manuscript according to the comments provided by the reviewers and have included our response to each comment in this document.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Ti-6Al-4V (Ti64) is a well-known Ti-based alloy and has been widely studied in previous research. This manuscript titled “Microstructural Development of Ti-6Al-4V Alloy via Powder Metallurgy and Laser Powder Bed Fusion” studied the differences between microstructures and mechanical properties of Ti-6Al-4V fabricated via powder metallurgy (PM) and laser powder bed fusion (L-PBF) 3D printing. The study tries to clarify the mechanisms of higher hardness observed in L-PBF sample by comparing the morphology and crystal structure with the PM samples. This has been associated with the laths morphology and refinement of single phase α′ in L-PBF parts, whereas another two phases α and β influence the micro-hardness in PM samples. The results are solid for understanding microstructures and mechanical behavior in different samples. The observations are significant for the potential development of TiAlV alloy engineering. Hereby, I suggest the publication of this paper in the journal “Metals” with minor revisions as below:
11. Page 3. Line 101.
The number of density (99.85 %) is a minor different with that of the cited ref. [21] as 99.86 %. Please consider and correct the parameter if necessary.
22. Page 4. Line 154.
Remove the text “one hundred and thirty” and parentheses.
33. Page 10.
The figure 8(b) should be modified accordingly.
44. Page 10. Line 271 - 272.
“However as previously explained, the sintering temperature seems to be more effective in lowering the level of porosity than the compacting pressure.” There is no evidence to verify this sentence since only two parameters has been selected for both temperature and compact pressure in this study. O the other hand, the porosity could be lowered either by increasing sintering temperature or compacting pressure.
55. Page 10. Line 277 - 278.
The hardness parameters “304 ± 12 HV” cited from one unpublished paper should be treated carefully. On the other hand, it should be clarified why the special L-PBF sample hardness is taken into account instead of the number from as-printed L-PBF sample.
66. Page 11.
Please zoom out figure 9 so that all markers placed on the figure properly.
Author Response
We would like to convey our appreciations to both the editor and reviewers of our manuscript and the opportunity to enhance the quality of the article. We have carefully revised the manuscript according to the comments provided by the reviewers and have included our response to each comment in this document.
Author Response File: Author Response.pdf
