Reduction of Residual Quenching Stresses in 2A14 Aluminum Alloy Tapered Cylinder Forgings via a Novel Cold Bulging Process
Round 1
Reviewer 1 Report
This paper suggested a method of relaxing the residual stress, which is hard to be removed from the material they studied. It is a well-known characteristics of the material and industrially important. The presented method is practical. The manuscript were properly organized and the schemes and/or approaches were evaluated to be well-organized. So I recommend that this paper be acceptable. However, we did not check the English.
Author Response
We thank you very much for giving us an opportunity to revise our manuscript. We are very sorry that the language of the article is not completely satisfactory. We have read the manuscript carefully and corrected the errors. Also, we have submitted our manuscript to Editage (app.editage.cn) for English language editing.We hope the language of our revised manuscript can meet the professional requirements.
Reviewer 2 Report
Several citations are used inappropriately. [11] and [12] describe magnetic methods of stress relaxation in ferromagnetic steels, while aimed material of paper are paramagnetic aluminum alloys! Moreover, authors of [11] conclude: "(...) This is proved bysome experiments performed by the authors in non-ferromagnetic material Al, in which no stress reduction occurs after magnetic treatment".
A photo of obtained real tapered cylinder forging is reqired.
What was the influence of the curvature of the sample surface on the residual stress results, measured using the strain gauge hole drilling method?
What character of residual stresses by hole drilling method was identified - compressive or tensile? It's not clearly shown in the article.
How was the direction of measured stresses - hoop or axial?
What about depth of measurement? The deep of the drilled hole was 2 mm, so stresses were measured as surface or sub-surface?
For better understanding, authors after describing which kind of stress were measured, should on the same graph to compare FEM and experimental streses in adequate points.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 3 Report
The authors investigated the residual stress of 2A14 aluminum alloy processed by cold bulging. Residual stress of quenched material is important engineering issue and the details of the residual stress associated with the quenching and subsequent mechanical processing was well documented.
Several suggestions from the reviewer were listed as bellow,
Comment 1.
The reviewer agree with the reduction of the residual stress after the bulging process. Regarding the residual stress analysis for the tapered cylinder as predicted by FEM, large magnitude of residual stress induced by quenching heat treatment was decreased by the cold bulging process. Considering the fact that the homogeneous thermal strain does not provide any residual stress inside the solid, inhomogeneous distribution of the thermal strain was introduced by quenching.
According to the author’s statement in Fig.14, “Assuming a uniform plastic strain acted on the material during the cold deformation process, the final residual stress distribution post cold deformation was denoted as 2S-2C-2S.”
As the reviewer mentioned in the above, plastic strain introduced by the bulging process should be inhomogeneous one since the thermal strain was inhomogeneous. If plastic strain by mechanical process was homogeneous, magnitude of plastic strain was much greater than that of thermal strain. Otherwise, resultant sum of thermal strain and plastic strain should be homogeneous eventually.
Comment 2.
Figure 16 clearly shows fine precipitates in nano-size. Judging from the zone axis of STEM images, there are a lots of small dots, which implies existence of needle type precipitates along [001] as the author mentioned. However, θ’ phase is usually known as the plate-shaped precipitate on {001} habit plane. Pls reconsider the phase analysis for the needle shaped precipitates, or explain the reason why the θ’ phase can be seen as the needle-shape.
Comment 3.
Units of length and stress magnitude are missing in schematic (Fig.1) and simulation results (Fig.7-9).
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Dear Authors
Thanks for experimental section improving, but indexes σmax /σmin in the Table 4 are used in the right order? Also ß parameter should be shortly explained.
In my opinion, in the introduction, you should find appropriate citations with methods of residual stress relaxation, instead of simply deleting the words "aluminium alloys"
Author Response
Thank you very much for your nice suggestion. I am sorry for the mistake of σmax /σmin in the Table 4. β parameter represents the principal stress direction angle. In our revised manuscript, re-select the cited documents to make the article more rigorous. Thank you again.
