Parametric Study of Fixtured Vibropeening
Round 1
Reviewer 1 Report
It can be recommended to arrange the literature in an appropriate manner: in order how the cites appear in the text, and the list of references should also be formatted according to one stadnard. It is also recommended to check the titles and numbers of sections, as well as some additional information about the conditions of the conducted experiment.
Author Response
The author has taken note of the reviewer comments to organize the literature in a more organized manner and cite as per appearance in the body of the paper. The references have thus been re-numbered and one standard formatting style as per endnote used.
Extra conditions of the conducted experiments such as details on XRD measurements have been added as highlighted in yellow. The sections particularly on the results and discussion has been checked again; however this section also has some part on the experimental variables used for the experiments; as these are specific to III A. Immersion Depth and III B. Process Time. So the authors strongly believe that these variables are emphasized in these sections rather than as a stand alone in the methodology section.
Reviewer 2 Report
The authors present an interesting research work on a vibropeening surface treatment of Inconel (IN) 718 alloy for arospace applications. In particular, they describe the experimental campaign conducted in order to evaluate the influence of process parameters, i.e. immersion depth and process time, on the Almen deflection, residual stresses and surface roughness. The reviewer suggests to accept the article after minor revisions, as reported in the following:
- The methodology is prevalently described in the next chapter of "Results and Discussions". The reviewer suggests to describe the methods in the "Methodology" chapter, leaving in the next one only the results with the appropriate discussions, for a more fluent reading. Moreover, the numbering of chapters is the same for "Methodology" and "Results and Discussions". Please, correct with a progressive numeration.
- In Fig. 4 and Fig. 5 the authors use different labels for the ordinates, please make uniform.
- In Fig. 4 the authors report the results only of few combinations of the process parameters presented in Table 1. Why did you choose only those combinations? Please, clarify such a choice.
- Line 174: the authors refer to a section "3.1" which is missing in the numbering of chapters and sections.
Author Response
The authors have taken note of the reviewer comments
-The sections particularly on the results and discussion has been checked again; however the authors believe that it is best for the experimental conditions that are specific to III A. Immersion Depth and III B. Process Time to be in this section itself - rather than as a stand alone in the methodology section. The methodology section describes the general setup of the trough and more details on the XRD have been included that have been highlighted in yellow
-As mentioned in the body of the paper,Figure 4 is an example from Electronics Inc on the saturation curve solver. Figure 5 is the plot of intensity v/s immersion depth as per the experiments conducted plotted on excel. Hence the difference in styles
-Three levels- at the surface of media, one at the center of the bulk of the media and the third at the lowest point of the media bulk at which the workpiece can be immersed without any interference from the trough lining, are the ideal levels for the study of immersion depth for the vibratory trough that was used in the experiments. Initial experiments however concluded that there is a point well within the center of the media bulk wherein the best position would be at- hence the selection of points at -60mm and -130mm as well in addition to 0mm(at the surface of media) and -200mm (at the lowest point of the trough where workpiece on fixture can be immersed).
-The authors cannot seem to address this comment . All chapters and sections have been appropriately checked and "3.1" is not found.
Reviewer 3 Report
This manuscript deals with vibropeening of nickel super alloy IN 718 and investigate influence of various peening parameters on the surface state after vibropeening. The study is quite weak and I have found a lot of issues being missing or debatable as follows:
- Some sentences are difficult to understand and so English should be improved,
- Literature sources are cited in the random order,
- Fig. 1 and Fig. 2 are quite idle,
- Indicate how Almen intensity was measured,
- Provide further details about XRD measurement,
- Provide full information about Inconel 718 – chemical composition, mechanical and other properties, microstructure image and especially information about samples history since the as received surfaces contain quite high magnitude of compressive stresses,
- Figure associated with the process kinematic which clearly present the meaning of the different peening parameters would be beneficial,
- Please provide information about the mutual relationship among the parameters indicated in Tab.1 (AL01 – provide specification),
- Fig. 4 is an example of Almen intensity versus peening time – please clearly indicate specifications (conditions of penning associated with this figure) and provide results for all parameters indicated in Tab.1,
- Red line in Fig. 4 shows nothing,
- Organization of the paper is poor – authors should clearly distinguish among experimental conditions, methodology, results of measurements and discussion of obtained results,
- Number of cited sources is very limited,
- Authors indicate longitudinal and transverse direction – clearly indicate samples history before peening as well as the way in which samples orientation was indicated with respect to the different directions,
- The differences among the different peening times with respect stresses is low and therefore peening time effect is only minor, authors indicated that the optimal peening conditions should be found but results in Fig.9-12 do not indicate remarkable differences,
- only ascending part of stress profiles indicate certain differences but such behaviour is less important since the reliable operation of Ni super alloys would be mostly depend on near subsurface layers – as we can see stresses in this region are nearly the same,
- author indicate stress relaxation after 2 hours of peening which is not true as Fig. 9 and 10 indicate,
The most essential aspects of my review is associated with the content of the manuscript – the main body is associated with stresses and FWHM. Vibropeening remarkably alters surface state; therefore the stress profiles represents only limited information about surface and information about microstructure alterations is fully missing. Being so, further observation have to be carried out such as metallographic observation, SEM observation, microhardness measurements and surface roughness measurements. Since such analyses are time consuming and would remarkably change appearance of the whole manuscript I recommend to reject the study, carry out the aforementioned analyses and edit a new version of the manuscript.
Author Response
- The authors have ensured due diligence and revised English wherever need be
- The authors have taken into consideration the reviewers comments and now the references are in order as they appear in the body of the text
- Figure 1 and 2 illustrate the Walther Trowal vibratory trough used and the steel satellite media used for experiments
- This is mentioned in Section II methodology and highlighted in yellow
- This has been included in Section II methodology and highlighted in yellow
-As mentioned in Section II on methodology, this Inconel alloy IN718 is similar as high pressure compressors (HPC) blisk condition, which is degreased, heat treated and anodized. The heat treatment steps are Rolls-Royce proprietary information and hence will not be listed down in this paper
- The authors believe that literature on vibratory finishing has well established the different processing parameters and the relationship; as can be found in the Gillespie's handbook on mass finishing. Hence the authors did not include the fine details on the relationship between parameters. However, for the purpose of the study, used a set of operating parameters that were fixed and studied the effect of immersion depth and process time.
As far as AL01, this is a compound from Walther Trowal that is commonly used to treat aerospace components. The information remains proprietary of Walther Trowal. The authors have included the trademark symbol TM to highlight this in the paper.
- Figure 4 is an example from electronics inc on saturation curve solver and for illustration purposes only.
-Figure 4 as mentioned in the previous pointer is an example from electronics inc for saturation curve solver.
- As mentioned to the other reviewers as well, the authors believe that the experimental conditions as stated in Section III A on immersion depth and Section III B on process time should be in this section itself to emphasize on the operating parameters that were used specific to the study. The section on methodology contains details about the trough used and more on the measurement methodology. The authors have ensured due diligence to ensure good flow of the paper for easy reading.
- The authors have ensured due diligence and ensured that relevant and sufficient references in the context of the paper have been cited. There are limited papers on vibropeening process study due to the proprietary new process.
-As presented in section on process time, the authors ascertain that the best peening is obtained between 2 and 4 hours as the stress profiles are comparable. At 8 hours, the stresses decrease as can be inferred from the plots, as well as from the FWHM. Typically, Almen strips are used to plot saturation curves and study process saturation time. The authors used a different concept of studying saturation with respect to Residual Stress on IN718 flat work pieces.
-The authors agree with the reviewer- however this is a hypothesis that the authors make due to the observed differences in stress profiles and degree of cold work from FWHM plots.
- The authors have taken the view of the reviewer and believe that the studies recommended by the reviewer are worth conducting and will be done as part of future work. This has thus been included in future work section of the paper. The focus on this paper is typically on Almen intensity, Residual Stress and plastic deformation that is typically used to quantify any peening process of aerospace components, which can be seen from most of the literature related to vibropeening.
Round 2
Reviewer 3 Report
Comparing the first and revised version of the manuscript, authors did nearly nothing essential considering the manuscript quality. The study does not fill the aim to find optimized conditions for peening process since stress profiles as well as FWHM do not exhibit remarkable difference. The peening studies should be mostly focused on the surface state and authors provide information from XRD technique only. Moreover, the results of stresses and FWHM are contradictory. Evaluation of metallographic observation, microhardness, SEM observation, ect. are mandatory a must be included in the manuscript. Authors indicate that such observation should be carried out in the near future. I accept it but current version of the study is absolutely unacceptable and the manuscript should be rejected. This study is very poor, contains author data interpretations which are not true as well as conclusions.
My final decision - I strongly recommend to reject the study.
Author Response
The authors have studied two key important parameters concerning Vibropeening: Immersion Depth and Process Time. The study aims to create a sense of awareness among researchers and experts in this field that for every given experimental setup, there is an optimum depth at which the best peening action takes place (and this is at the centre of the bulk of media) and not necessarily at the bottommost point of the vibratory container (as in the case of vibropolishing). As with process time, it is for the first time, that the authors have proposed the study of using flat coupons as a means to calculate saturation time as Almen strip may not necessarily be the best means to quantify vibropeening process. The authors through this study aim to bring to light that there is an optimal time for every experimental setup, and more time does not necessarily mean better peening, but there maybe a saturation that may come about. This is particularly useful for industries to peen at the desired process time and save costs accordingly by avoiding higher cycle times as well as the adverse effects that may come about by over peening.
The authors have ensured due diligence that relevant results supported by references from previous studies have also been included in the results and discussions section to support the work conducted. This has been enhanced with plausible reasoning putforth by the authors, backed by the physics of the process as well as references from previous work in this area.
The authors agree that residual stress and FWHM are just not the only output parameters to quantify vibropeening. However, like with most research in this field, residual stress and FWHM remains the most important parameter and hence the focus of this work. The authors have included in future work additional work such as micro structure analyses as reccomended by the reviewer.
Lastly, as mentioned in the body of the paper, some information is proprietary as this work was done in conjunction with Rolls-Royce. As such, the paper has gone through the relevant industry check in terms of the results and analyses presented. The interpretation of data and the conclusions made are therefore after due diligence and supported through the references and various industry experts.
