Investigation on the effects of using Nano-size Al2O3 powder on the mechanical and microstructural in the multi-passes continuous friction stir welding of the 2024-T6

Nazari, Mohammad; Besharati Givi, Mohammad Kazem; Farahani, Mohammad Reza; Mollaei Milani, Javad; Mohammad Zadeh, Hassan

Investigation on the effects of using Nano-size Al2O3 powder on the mechanical and microstructural in the multi-passes continuous friction stir welding of the 2024-T6

Authors

Mohammad Nazari

Mohammad Kazem Besharati Givi

Mohammad Reza Farahani

Javad Mollaei Milani

Hassan Mohammad Zadeh

Abstract

The main aim of this experiment is to investigate the effects of Nano-size Al2O3 on the mechanical properties and microstructure of multi-passes friction stir welding of Al 2024 lap joint. Nano particles were added into the joint line. A combination of rotational speed and travelling speeds were performed. Optical microscopy and scanning electron microscope were used to investigate the microstructure and fracture surface of samples respectively. Optimum condition (sample) was selected due to highest ultimate tensile strength (UTS). It was seen that sample which included Nano particles and fabricated by 1400 rev/min rotational speed and 16 mm/min travelling speed in second pass of continues welding had improvement in UTS in comparison to one pass welded sample of particle free and after that increasing the number of passes reduce the UTS. The average micro hardness of the sample which was particle rich were increased in comparison to particle free sample in nugget zone. Increasing the number of passes was not effect average micro hardness in nugget zone significantly. Grain sizes were reduced by 2 passes welding and after that no significant reduction has been seen.

Keywords

Friction Stir Welding

Ultimate tensile strength

Micro-hardness

Nano-size Al2O3

Grain size