VHCF Behavior of Inconel 718 in Different Heat Treatment Conditions in a Hot Air Environment
and Martina Zimmermann 1,2
Round 1
Reviewer 1 Report
1. As described on page 2, line 90, “The gauge length 89 of batch 1 was 10 mm (test volume 126 mm²), while the gauge length of batch 2 was limited 90 to 5 mm (test volume 63 mm²)…” Please explain the effect of the size effect caused by the volume difference of the specimen on the fatigue performance.
2. On page 3, line 127, please explain the effect of different pulse times and pause time in ultra-high cycle fatigue testing. Please supplement the tensile properties of the material at high temperature.
3. Please describe the temperature distribution within the gauge length segment of the specimen.
4. It is well known that the fatigue crack initiation life in ultra-high cycle fatigue accounts for more than 90% of the total life. The analysis of fatigue crack growth behavior in this paper does not seem meaningful. What is the basis for the crack growth cycles indicated by the arrows in Figure 7.
5. Please explain the position of the observation area in Figure 8 and Figure 9 in the gauge length or fracture of the fatigue specimen.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper presents interesting results of research on the behavior of VHCF Inconel 718 under the influence of various heat treatments.
The detailed comments are as follows:
1. It would be nice to show the figure of the specimen and its dimensions.
2. Fig. 6 - please add units next to Nf.
3. It would be good to give the material properties of the tested material, e.g. material strength and others.
4. Were brittle or mixed cracks observed more often?
5. In conclusion, point 5 should be 6x10 to the 7th.
6. It would also be worthwhile to quote the following papers: 1) Fatigue behavior of metastable austenitic stainless steels in LCF, HCF and VHCF regimes at ambient and elevated temperatures. Metals 2019, 9, 704, 2) Study of the fatigue crack growth in long-term operated mild steel under mixed-mode (I+II, I+III) loading conditions, Materials Vol. 13, 160, 2020. doi:10.3390/ma13010160
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
A very interesting study. The material and methodology of the research was presented clearly and completely. The analysis and discussion of the results was carried out correctly and topped off with accurate conclusions.
Only small editorial mistakes (lines 75, 76, 313, and 316), were found, some problem with automatic reference I suppose. And one doubt needs to be solved: were both batches 1 and 2 had exactly the same chemical composition as that presented in Table 1 or is it only standard requirements?
However, I find the study very valuable and will undoubtedly interest the readers. I fully recommend the article submitted for review for publication.
Author Response
Response to Reviewer 3 Comments
The authors of this study would like to thank the reviewer for his kind and constructive comments and recommendation.
The problems with the automatic reference have been improved. Thank you for the very important comment.
The chemical composition shown in Table 1 is the material composition specified by the manufacturer. Both batches were manufactured from the same round material and therefore have the same composition. This confusion has been corrected in the text.
