Friction Stir Welding of AA5754-H24: Impact of Tool Pin Eccentricity and Welding Speed on Grain Structure, Crystallographic Texture, and Mechanical Properties

Mohamed M Z Ahmed; Ahmed R S Essa; Sabbah Ataya; Mohamed M El-Sayed Seleman; Ali Abd El-Aty; Bandar Alzahrani; Kamel Touileb; Ashraf Bakkar; Joffin J Ponnore; Abdelkarim Y A Mohamed

doi:10.3390/ma16052031

Friction Stir Welding of AA5754-H24: Impact of Tool Pin Eccentricity and Welding Speed on Grain Structure, Crystallographic Texture, and Mechanical Properties

Materials (Basel). 2023 Mar 1;16(5):2031. doi: 10.3390/ma16052031.

Authors

Affiliations

¹ Department of Mechanical Engineering, College of Engineering at Al Kharj, Prince Sattam bin Abdulaziz University, Al Kharj 11942, Saudi Arabia.
² Department of Metallurgical and Materials Engineering, Faculty of Petroleum and Mining Engineering, Suez University, Suez 43512, Egypt.
³ Mechanical Department, Faculty of Technology and Education, Suez University, Suez 43512, Egypt.
⁴ Faculty of Engineering, King Salman International University, El-Tor 45615, Egypt.
⁵ Department of Mechanical Engineering, College of Engineering, Imam Mohammad Ibn Saud Islamic University, Riyadh 11432, Saudi Arabia.
⁶ Mechanical Engineering Department, Faculty of Engineering-Helwan, Helwan University, Cairo 11795, Egypt.
⁷ Department of Environmental Engineering, College of Engineering at Al-Leith, Um Al-Qura University, Al-Lith 28434, Saudi Arabia.

Abstract

This study investigates the effect of tool pin eccentricity and welding speed on the grain structure, crystallographic texture, and mechanical properties of friction stir welded (FSWed) AA5754-H24. Three tool pin eccentricities of 0, 0.2, and 0.8 mm at different welding speeds ranging from 100 mm/min to 500 mm/min and a constant tool rotation rate of 600 rpm were investigated. High-resolution electron backscattering diffraction (EBSD) data were acquired from each weld's center of the nugget zone (NG) and processed to analyze the grain structure and texture. In terms of mechanical properties, both hardness and tensile properties were investigated. The grain structure in the NG of the joints produced at 100 mm/min, 600 rpm, and different tool pin eccentricities showed significant grain refining due to dynamic recrystallization with average grain sizes of 18, 15, and 18 µm at 0, 0.2, and 0.8 mm pin eccentricities, respectively. Increasing the welding speed from 100 to 500 mm/min further reduced the average grain size of the NG zone to 12.4, 10, and 11 µm at 0, 0.2, and 0.8 mm eccentricity, respectively. The simple shear texture dominates the crystallographic texture with both B¯/B texture component with the C component at their ideal positions after rotating the data to align the shear reference frame with the FSW reference frame in both the PFs and ODF sections. The tensile properties of the welded joints were slightly lower than the base material due to the hardness reduction in the weld zone. However, the ultimate tensile strength and the yield stress for all welded joints increased by increasing the friction stir welding (FSW) speed from 100 to 500 mm/min. Welding using the pin eccentricity of 0.2 mm resulted in the highest tensile strength; at a welding speed of 500 mm/min, it reached 97% of the base material strength. The hardness profile showed the typical W shape with a reduction in the hardness of the weld zone and a slight recovery of the hardness in the NG zone.

Keywords: AA5754-H24 aluminum alloy; crystallographic texture; friction stir welding; mechanical properties; microstructure; tool pin eccentricity; welding speeds.

Grants and funding

IF2-PSAU-2022/01/20939/Deputyship for Research & Innovation, Ministry of Education in Saudi Arabia