The Effect of Hot Oscillatory Pressing Temperature on Microstructure and Tensile Behavior of Powder Metallurgy Superalloy
, Dejian Sun 1,2,*, Jiachen Kang 1,2, Yang Gao 1,2, Xuewei Yan 3, Qiancheng Gao 1,2 and Ka Gao 4,*
Round 1
Reviewer 1 Report
The manuscript describes the effect of hot oscillatory pressing temperature on the microstructure and tensile properties of PM superalloy. They have claimed that the HOP process stands superior to the HP process in terms of enhanced mechanical properties. The authors have corroborated the data using SEM, EBSD and tensile tests. The HOP at 1160 C gives the best properties. Overall, the manuscript is well written and can be considered for publication after minor corrections. Fig. 3b shows a few more XRD peaks in the 1160-HOP sample. It would be good if the authors could index those peaks. Also, a standard XRD pattern should be given. Better quality SEM images in Fig. 9 should be given.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper is presented in a concise and scientific manner which positively contributes to the field. It fulfils the requirements of a scientific article. However, the following suggestions must be considered to publish this paper. The English language is understandable, but sometimes the sentences are used in the past tense. Usually, the tense of the paper presentation of graphs/figures is written in the present tense, and the lab work is presented in the past tense. Revision of the English language is advised.
1- The overall structure of the abstract is fine. Some words are repeated (for example, the tensile behaviour is mentioned two times in a sentence). Small grammatical mistakes must be eliminated before submission.
2- A brief introduction or literature review of the materials used in this study can be given. For example, the influence of HOP on the FGH4096 or the usage of this material for various applications must be provided.
3- It would be highly recommended to schematically present the HOP setup in graphs(to show increasing or oscillating temperature cures) or in the shape of the experimental setup. So that the reader could understand what types of processing methods/approach is being used. (page 2, line 57)
4- The author has extensively used past sentences in the results parts of the paper. I suggest using the present sentence where it says Figure xyz shows the xyz properties etc., instead of Figure xyz showed properties etc.
5- The white background around the text in Figure 8 has assisted in understanding the tags of th fracture modes much more clearly. Similar background must be added in Figure 6 to show the gamma prime phases.
6- Additional information about the sample preparation sample nature/size gauge length must be given for the tensile tests. Was the sample circular, rod, bar etc and if any standards were followed for tensile loading characterizations?
7- in Figure 11. How is the grain size measured? The question is not about the technical method or the philosophy behind the mapped grains and their texturing orientations. The jury member asks whether these grain sizes present the grain sizes within the particles? or if the particles shown in Figure 9, Figure 1 are considered individual grains? Additionally, how is the texture of the particles influenced as shown with the inverse pole figure in Figure 11 due to different temperatures?
10- For Figure 1 and 2. The magnification of the Figure 1 and 2 is same. They also belong to same samples, why do the interparticle boundaries disappear? from images shown in Figure 2? what is the difference in these two figure.
12- For Figure 12. Some foreign language titles must be translated into Englihs in the image.
13- The materials and methods part of the paper is not given in sufficient details. Specially the manufacturing methods and manufacturing parameters must be added. For example, a graph or schematic to show the oscillating mechanisms of the treatment profile should be given. Additionally, treatment durations must be added for HOP and HP.
14- Figure 4 tagged as 1, shows the presence of boride phases. But the XRD analysis indicates the absence of borides in Figure 3. What could be the reason? Additionally the XRD is characterized by only the presence of TÄ°C and Y/Y’ phases. Did any other phase not form in the superalloy despite high temperature treatment.
15- at row number 87-
‘method proposed by Ingesten N. et al. [33], the PPBs scales of the samples HOPed at 1120 87
ï‚°C, 1160 ï‚°C, and 1200 ï‚°C were 3, 2, and 1, respectively, and that of the 1200 °C-HP sample 88
was 2.’ What is PPBs scale? Maybe ref. 33 has defined but it must also be added in this paper. At least the definition of the PP boundary scales. Reader must understand what it means to be a higher scale or lower scale value.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The paper is interesting and should be published after meeting my comments.
1. The manuscript should be written in a more self-explaining way. E.g. the HOPing description deserves writing one sentence.
2. It should be shortly described in which stages of HOPing the primary, secondary and tertiary gamma’ particles are nucleated and grown, so that the reader will understand the physics behind.
3. Fig. 2 does not bring any reasonable information – it should be omitted.
4. It seems to me that the presence of borides is not welcome. Why the boron content is not reduced just to avoid precipitation?
5. The authors should try to explain the positive effect of HOPing. The effect could be pronounced in the initial stage to enhance the densification process due to powder particle rearrangement provoked by stress oscillations. To support or disprove this hypothesis, the authors could apply the HOPing only during first one minute of the consolidation and then continue with HPing in their following work.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The manuscript can be accepted in this state.
