Feasibility of using coal as reinforcement in dissimilar welded joints: Comparative analysis

¹ Cape Peninsula University of Technology, Faculty of Engineering and the Built Environment, Mechanical and Mechatronic Engineering, Bellville, 7535, South Africa.
² University of South Africa, College of Science, Technology, and Engineering, School of Engineering, Department of Mechanical Engineering, Florida Campus, South Africa.
³ Durban University of Technology, Faculty of Engineering and the Built Environment, Mechanical and Mechatronic Engineering, Steve Biko Campus, Durban, 4000, South Africa.

^* Corresponding author: msomiv@gmail.com

Abstract

This study explores the possibility of using coal as reinforcement in dissimilar welded joints. The study involved joints of AA5083 and AA6082 alloys, which underwent friction stir welding (FSW), friction stir processing (FSP), and FSP with added coal powder (FSP+Coal). Microstructure analysis, microhardness testing, tensile tests, and fracture surface analysis were evaluated. The results indicated that FSP+Coal joints exhibited promising mechanical properties, with failure initiation at 130 MPa and a tensile strain of 6%, and complete failure at an ultimate tensile stress (UTS) of 144 MPa and a tensile strain of 9.5%. In comparison, FSP joints showed failure initiation at 130 MPa and a strain of 8.5%, and complete failure at 90 MPa and a strain of 14%. Additionally, FSP+Coal joints demonstrated a higher average hardness (8.3% higher than FSW joints and 4% higher than FSP joints), supported by fracture surface and microstructural analyses indicating a finer grain size of 13.15 μm in FSP+Coal joints, compared to 12.79 μm in FSP joints and 39.74 μm in FSW joints.