**4. Conclusions**

In this study, the effect of defocusing and laser offset on the microstructures of dissimilar AA6061/Ti-6Al-4V joints, intermetallic layer size and intermetallic particles size and distribution were analyzed. Moreover, the tensile performances with and without the stress relief heat treatment at 530 ◦C for 2 h and ultrasonic peening treatment were studied and compared. The aim of this research is to provide an opportunity for researchers and the welding industry to overcome the low ductility of Al–Ti welds using mechanical treatment, since, to date, the research based on post-weld heat treatments on dissimilar joints has not been effective.

The main conclusions are the following:


**Author Contributions:** Conceptualization, P.L.; methodology, P.L.; validation, P.L.; formal analysis, P.L.; investigation, P.L., S.D., R.N., C.M., A.T.; resources, G.C.; data curation, P.L.; writing—original draft preparation, P.L.; writing—review and editing, P.L., R.N., C.M., S.D.; visualization, P.L.; supervision, P.L. 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:** The data presented in this study are available on request from the corresponding author.

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