# Influence of Cutting Parameters and MQL on Surface Finish and Work Hardening of Inconel 617
## 5 Conclusions and Future Directions
### Future Work  
Although this paper was able to address the gaps found in the literature on the machining of Inconel 617, there were still many limitations in the experiments that could be used to enhance future studies in this field. From the results of this paper, these are the experimental directions that are recommended for future studies:  
* When conducting MQL trials, it is recommended to include more than one deposition nozzle to lubricate the entire cutting surface as much as possible. This would include at least one nozzle for each cutting face on the tool--the rake face and the flank face--where the points of highest temperature occur. This would allow a better analysis on the total effects of MQL on tool wear.
* Study the effects of varying the air pressure delivered to the nozzles. This was not possible with the available MQL equipment as it only provided a constant air pressure.  
Studying the variation in air pressure may give a better understanding of the full breadth of the impact of MQL in machining Inconel 617.
* Test the effectiveness of advanced coatings in machining Inconel 617. Self-lubricating or ultra-soft coatings may be considered as candidates to improve the machinability of this material and has yet been tested extensively.
* Residual stress analysis performed through X-ray diffraction (XRD) can give a better understanding of how the Inconel 617 subsurface is affected by the machining process and provide insights as to how the machined components could perform under intense environments such as those in a nuclear reactor.
* Perform an in-depth assessment of the cutting parameters' interactions with MQL and flood coolant deposition to determine the impact the interactions between the cutting parameters and coolant deposition techniques have on the surface finish of machined Inconel 617.
* Study the influence of the surface deformation layer on the corrosion and oxidation resistance properties, as well as chemical composition of Inconel 617. While the high resistance properties of this alloy are largely known, it is insightful to understand how the manufacturing of this metal generates a deformation layer and how it will impact its properties in nuclear applications.
* Chip morphology analysis can provide further insight into the impact of MQL and flood coolants on the quality of the machined surface and its influence on tool wear. It is recommended to perform chip analyses to determine the cutting modes in machining Inconel 617.  
Conceptualization, R.L.; methodology, R.L.; formal analysis, R.L.; investigation, R.L.; data curation, R.L.; writing--original draft preparation, R.L.; writing--review and editing, R.L., J.M.D. and A.H.C.; visualization, J.M.D. and A.H.C.; supervision, S.C.V.; project administration, S.C.V.; funding acquisition, S.C.V. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) under their Discovery Research Grant Program RGPIN-2019-07096.  
Not applicable.  
The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.  
The authors declare that they have no financial interest or personal relationships that can inappropriately bias this work.  
The following abbreviations are used in this manuscript:  
ASME American Society of Mechanical Engineers  
BPVC Boiler and Pressure Vessel Code  
BUE Built-up edge  
LPBF Laser Powder Bed Fusion  
MAF Magnetic Field-Assisted Finishing  
MQL Minimum Quantity Lubrication  
MRR Material removal rate  
MSR Molten Salt Reactor  
SMR Small Modular Reactor  
VHTR Very-High-Temperature Reactor  
XRD X-ray diffraction