**4. Conclusions**

The authors showed that it is reasonable to use exploratory data analysis for the evaluation of the properties of RE oxide modified pad welds. In order to optimise the results, it is advisable to perform a number of additional experiments to expand the database. The expanded database will be used to predict the optimal parameters (chemical composition, percentage of rare Earth elements, padding method, etc.) while maintaining the best wear resistance. The results obtained so far indicate dependency between geometry indices and mechanical properties (friction coefficient, instrumental hardness).

Exploratory data analysis allowed determining directly proportional (positive correlations) and inversely proportional (negative correlations) dependencies. A significant dependency was observed for the "C" index, i.e., the effect of carbon on hardness, friction coefficient, and geometry indices (track area, track depth), which may result from the change in the pad weld morphology after introducing RE oxides. This issue will be addressed by the authors in their next work.

The study and analyses demonstrate that exploratory methods capture non-trivial dependencies of the obtained results.

The analysis of the results of tribological tests is the basis for the development of new techniques of forming surface layers and coatings with increased wear resistance. The wear indicators analysed in this study indicate further direction of surface modification research. The EDA results contributed to the knowledge on the influence of surface modification with rare Earth oxides on wear resistance. The study presented in this article offers a guidance to continue work on the technology of the surfacing process, selection of modifiers, and welding materials for surface layers.

**Author Contributions:** Conceptualization, J.K. and P.M.; methodology P.M. and J.K.; software, P.M.; validation, J.K., P.M. and M.M.; formal analysis, J.K., P.M., and M.M.; resources, S.R., J.K. and M.M.; data curation, S.R. and P.M.; writing—original draft preparation, J.K. and P.M.; writing—review and editing, J.K., P.M. and M.M.; visualization, P.M. and J.K.; supervision, J.K. and M.M. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Data sharing not applicable, all the data created for this study are already displayed in the article.

**Conflicts of Interest:** The authors declare no conflict of interest.
