Nur Syafiqah, Nor Sofian and Luqman Hakim, Ahmad Shah and Mahadzir, Ishak@Muhammad (2025) A parametric study on the effect of pilot hole diameter on the mechanical and microstructural properties of AA6061-AA7075 friction stir spot welding. Journal of Adhesion Science and Technology, 39 (14). pp. 2262-2279. ISSN 0169-4243. (Published)
![[img]](http://umpir.ump.edu.my/style/images/fileicons/other.png) |
Pdf
A parametric study on the effect of pilot hole diameter.pdf Restricted to Repository staff only Download (7MB) | Request a copy |
Abstract
This study investigates the impact of pilot holes and welding parameters, including pilot hole size, rotational speed, and dwell time on the mechanical and microstructural properties of dissimilar (7075-6061) aluminum joints using friction stir spot welding. Mechanical properties were assessed using shear and hardness tests, while microstructural analysis involved optical microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDX). The Taguchi approach determined optimal process parameters. Pilot hole size guidelines in welding were introduced, called pilot hole to keyhole (PTK) ratio. Results show that a specimen with a 4 mm pilot hole, 800 rpm rotational speed, and 5-s dwell time achieved a maximum ultimate shear strength (USS) of 89.29 MPa, closely matching the Taguchi-calculated value of 81 MPa with a 9% error. The HAZ has the lowest hardness, averaging at 76.3 ± 2 HV, while the SZ shows intermediate hardness, averaging at 83.8 ± 3 HV. Analysis of variance (ANOVA) results indicate that pilot hole size is the most significant factor, contributing 97%. Specimens with a 4 mm pilot hole size (0.7 PTK) ratio demonstrated the highest shear strength due to superior material mixing compared to those with 5 mm (0.8 PTK) ratio and 6 mm (1 PTK) ratio pilot hole’ size. SEM identified two distinct areas on the joint surface, and EDX confirmed AA7075 as the predominant joining material. These findings suggest pilot hole size affects the material’s mechanical and microstructural properties.
| Item Type: | Article |
|---|---|
| Additional Information: | Indexed by Scopus |
| Uncontrolled Keywords: | Dissimilar aluminum (AA6061-AA7075) joints; Friction stir spot welding (FSSW); Mechanical properties; Microstructural analysis; Pilot hole sizes; Shear strength; Taguchi method |
| Subjects: | T Technology > TJ Mechanical engineering and machinery |
| Faculty/Division: | Institute of Postgraduate Studies Faculty of Mechanical and Automotive Engineering Technology |
| Depositing User: | Mrs Norsaini Abdul Samat |
| Date Deposited: | 28 Jul 2025 03:14 |
| Last Modified: | 28 Jul 2025 03:14 |
| URI: | http://umpir.ump.edu.my/id/eprint/45189 |
| Download Statistic: | View Download Statistics |
Actions (login required)
 |
View Item |