Effect of Heat Treatment on the Microstructure and Hardness of Ni-Based Alloy 718 in a Variable Thickness Geometry Deposited by Powder Fed Directed Energy Deposition
, Haize Galarraga 1, Anabel Pérez-Checa 1, Mikel Ortiz 1, Amaia Alberdi 1, Trunal Bhujangrao 1, Elena Morales 1 and Eneko Ukar 2Round 1
Reviewer 1 Report
This paper presents good interest. In the paper, the authors presented the microstructure and hardness of Inconel 718 in a variable thickness geometry produced by Powder-fed Directed Energy Deposition. They also compared these properties after heat treatment. The article is informative and suitable for publication, but the following changes need to be made to improve the article.
1. The full form of DED should be mentioned in the first line of the abstract.
2. The full form of AMS should be mentioned in line number 21.
3. It is suggested to add the references in the first two paragraphs of the introduction section.
4. This paragraph (in lines 199 to 204) is somewhat difficult to understand. Rephrasing the paragraph is needed.
5. The following sentences should be rephrased to make them easier to understand.
“Kirka et al. [30] deposited a squared structure by Electron Beam Melting (EBM) at 60 kV with a preheat temperature of 975°C during the additive process, followed by a HIP treatment and solution treatment at 1066°C hold 1 hour, resulting in a remain of the columnar structure with yield and ultimate strength within ASTM F-3055 standard.”
“In the works of Zaharia et al. and Zhang et al. the structure after homogenization presented uneven overall recrystallized grains and hardly partial recrystallization with-out this heat treatment.”
“Although there are differences in the use, temperature and holding time of the homogenization treatment, both the solution and aging treatments (STA) showed in Table 3 are Inconel 718 standard heat treatments conforming to Aerospace Material Specifications (AMS)”
“Due to the large grain size obtained at high laser power conditions, common heat treatments do not produce recrystallization of the deposited material, excluding an uneven overall crystallization in the dilution zone and the first deposited layer due to the initial lower grain size obtained in that zone when depositing.”
6. Here 'or' in line 325 should be 'and'.
Author Response
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Author Response.pdf
Reviewer 2 Report
The paper is very well written, clear and understandable. It puts its observations into the context of the relevant old and new literature. I like very much that the authors used a hardness profile to reveal the hardness direct on the samples in Fig. 8 and 9, which shows the transition of the hardness on the entail sample clearly.
Author Response
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Author Response File: Author Response.pdf
