Proceedings of the International conference on Applied Research in Engineering,Science and Technology
Year: 2018 | Page No:18-28
Investigation of Microstructures and Mechanical Properties of the Joints Which Welded by the Pinless Tool and the Designed Tool to Reduce the Keyhole in the Friction Stir Spot Welding
Fatih Kahraman , Ayça Demirer Kahraman , Coşkun Yolcu , Gökçe Mehmet Gençer and Muammet Tüm
To eliminate or minimize the keyhole in the friction stir spot welded (FSSW) joints, a new FSSW tool was designed for minimum notch effect in the thick AA6063-T6 sheets. The designed FSSW tool and the pinless tool were manufactured AISI H13 hot work tool steel and then were heat-treated. The hardness of the hardened tools were 54–56 HRC. Lap joint welding was made with a dwell time of 3s and with a different rotational speed for every spot weld. After the welding procedures, microstructure and mechanical properties of welded with the pinless tool and designed tool were investigated. Characteristic fine grain in the stirring zone has formed in the welded samples with the designed tool as a result of the deformation, unlike the pinless tool. The amount of material flow out in the contact zone increased with increasing the rotational speed in both of the tool geometries. The highest shear/tensile strength are obtained at the lap welded samples with 1200 rpm in the designed tool. The increase in welding rotational speed causes welding distortion. The distortion of the welded joints with the designed tool is more apparent.
Keywords: FSSW, pinhole, tool design, AA6063, lap shear/tensile strength.