Influence of Different Annealing Atmospheres on the Mechanical Properties of Freestanding MCrAlY Bond Coats Investigated by Micro-Tensile Creep Tests

Round  1

Reviewer 1 Report

Dear Aurhors,

you present very large dataset, however, your conclusions are limeted to an empirical simple model. Discussion of the results assuming material effecs  (phase composition and  morphology effects  not only grain size) could give  more general  significance  of your work.

Additionally, please  correct some figure captions ( e.g. Figs. 2,4,5,6, 4%H2O?+2%H2O) 

Author Response

Submission of manuscript: Influence of Different Annealing Atmospheres on the Mechanical Properties of Freestanding MCrAlY Bond Coats Investigated by Micro-Tensile Creep Tests

Dear Professor Lopez,

We would like to thank the reviewers for their comments and suggestions. We have improved the paper based on their helpful suggestions. We are pleased to submit a revision of the manuscript entitled “Influence of Different Annealing Atmospheres on the Mechanical Properties of Freestanding MCrAlY Bond Coats Investigated by Micro-Tensile Creep Tests,” by Sven Giese, Steffen Neumeier, Jan Bergholz, Dmitry Naumenko, Willem J. Quaddakkers, Robert Vaßen and Mathias Göken. A discussion of the specific changes made based on the reviewer’s comments follows. Any changes to the text or captions are highlighted in yellow in the submitted document.

Reviewer 1

You present very large dataset, however, your conclusions are limeted to an empirical simple model. Discussion of the results assuming material effecs  (phase composition and  morphology effects  not only grain size) could give  more general  significance  of your work.

Additionally, please  correct some figure captions ( e.g. Figs. 2,4,5,6, 4%H2O?+2%H2O)

Author Comment:

Material effects like phase composition, area fraction of the individual phases as well as grain size without the influence of different annealing atmospheres were studied in more detail in a former study [1]. All these material properties were not significantly influenced by oxygen, water vapor or hydrogen additions during the annealing. Figure captions are corrected in the paper.

Thank you again for your comments and feedback. Please contact us if any additional information is necessary to facilitate the review process. We look forward to a favorable decision on this manuscript.

Sincerely,

Sven Giese

Department of Materials Science

Friedrich-Alexander University

[email protected]

Literature:

1.         Giese, S.; Neumeier, S.; Amberger-Matschkal, D.; Bergholz, J.; Vaßen, R.; Göken, M. Micro-tensile creep testing of freestanding MCrAlY bond coats. J. Mater. Res. 2019.

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper deals with investigation of mechanical properties of low-pressure plasma sprayed (LPPS) MCrAlY (M=Ni, Co) 16 bond coats, Amdry 386, Amdry 9954 and ODS (oxide dispersion strengthened) Amdry 9954 (named 17 Amdry 9954 + ODS)  after annealing in three atmospheres, Ar-O2, Ar-H2O and Ar18 H2-H2O. 

The paper is of interest for the journal and present interesting experimental results for the development of Single Cristal Superalloys for application in power plants.

Some minor remarks

1) Could  be useful to give:

- an indication about the reason for which the limited range of temperature 900-950 ° has been considered.

- an indication about the relevance of the stress level considered for the creep tests;

2) Use a space after text and before the reference "xxx [yy]"

3) check the caption of Figure 2 according the sequence of the images a-c, d-f, g-i;

4) Please use "minimum strain rate" instead of "creep minimum" and "creep strain" instead of "plastic strain"

Author Response

Submission of manuscript: Influence of Different Annealing Atmospheres on the Mechanical Properties of Freestanding MCrAlY Bond Coats Investigated by Micro-Tensile Creep Tests

Dear Professor Lopez,

We would like to thank the reviewers for their comments and suggestions. We have improved the paper based on their helpful suggestions. We are pleased to submit a revision of the manuscript entitled “Influence of Different Annealing Atmospheres on the Mechanical Properties of Freestanding MCrAlY Bond Coats Investigated by Micro-Tensile Creep Tests,” by Sven Giese, Steffen Neumeier, Jan Bergholz, Dmitry Naumenko, Willem J. Quaddakkers, Robert Vaßen and Mathias Göken. A discussion of the specific changes made based on the reviewer’s comments follows. Any changes to the text or captions are highlighted in yellow in the submitted document.

Reviewer 2

1) Could be useful to give:

- an indication about the reason for which the limited range of temperature 900-950 ° has been considered.

- an indication about the relevance of the stress level considered for the creep tests;

Author Comment:

Preliminary creep tests were performed with stresses of 10 - 26 MPa at 900°C. Lower stresses of 10 MPa resulted in a creep rate below 1x10^-8s^-1. These are very time consuming experiments for the TMA test setup. Stresses higher than 15 MPa lead to significantly higher strain rates of about 1x10^-3s^-1 - 1x10^-4s^-1. To compare different bond coats and testing temperatures a constant force of 2.37 N was chosen for all experiments. Further investigations will be performed at higher temperatures in combination with lower stresses. In this first study this temperature stress regime was chosen based on the preliminary tests before.

2-4)

·         Use a space after text and before the reference "xxx [yy]"

·         check the caption of Figure 2 according the sequence of the images a-c, d-f, g-i;

·         Please use "minimum strain rate" instead of "creep minimum" and "creep strain" instead of "plastic strain"

Author Comment:

Correction according to the reviewers comments were added in the paper.

Thank you again for your comments and feedback. Please contact us if any additional information is necessary to facilitate the review process. We look forward to a favorable decision on this manuscript.

Sincerely,

Sven Giese

Department of Materials Science

Friedrich-Alexander University

[email protected]

Author Response File: Author Response.pdf

Reviewer 3 Report

Excellent work, well written, well explained and obtaining sound results.

Just a few suggestions:

- A figure with the geometry of the specimens would be welcome, although the info is in the text.

- Review the text looking for (a few) tipos

- Present the results in the same order (e.g., Figure 5a and 5b changes the order and presents the results of H2O before than those of O2, whereas in Figure 4 and Table 2 is the other way round)

- the authors do not indicate the contributions of each one, something that (I think) is mandatory in this journal

Author Response

Submission of manuscript: Influence of Different Annealing Atmospheres on the Mechanical Properties of Freestanding MCrAlY Bond Coats Investigated by Micro-Tensile Creep Tests

Dear Professor Lopez,

We would like to thank the reviewers for their comments and suggestions. We have improved the paper based on their helpful suggestions. We are pleased to submit a revision of the manuscript entitled “Influence of Different Annealing Atmospheres on the Mechanical Properties of Freestanding MCrAlY Bond Coats Investigated by Micro-Tensile Creep Tests,” by Sven Giese, Steffen Neumeier, Jan Bergholz, Dmitry Naumenko, Willem J. Quaddakkers, Robert Vaßen and Mathias Göken. A discussion of the specific changes made based on the reviewer’s comments follows. Any changes to the text or captions are highlighted in yellow in the submitted document.

Reviewer 3

1)      Just a few suggestions:

- A figure with the geometry of the specimens would be welcome, although the info is in the text.

- Review the text looking for (a few) tipos

- Present the results in the same order (e.g., Figure 5a and 5b changes the order and presents the results of H2O before than those of O2, whereas in Figure 4 and Table 2 is the other way round)

- the authors do not indicate the contributions of each one, something that (I think) is mandatory in this journal

Author Comment:

The geometry of the specimen could be seen in figure 1 and is also described in the text. Information of the gauge length of 2500µm is added in the paper.

The order in figure 2 and 6 was changed so that it is H₂, H₂O, O₂.

The contribution of everyone who was contributing to this paper was clarified by uploading the manuscript and will if necessary added by the journal.

Thank you again for your comments and feedback. Please contact us if any additional information is necessary to facilitate the review process. We look forward to a favorable decision on this manuscript.

Sincerely,

Sven Giese

Department of Materials Science

Friedrich-Alexander University

[email protected]

Author Response File: Author Response.pdf