Effect of tool pin profile on the material flow characteristics of AA6061

• DOI: 10.1016/j.jmapro.2017.03.005
• Publication Date: 2017-03-19T03:46:47Z
• Authors: Arun Kumar Kadian; Pankaj Biswas
• Keywords: Material Flow; Weld line; Heat Generation

Abstract Friction stir welding is a well emerged solid state joining process for softer materials. It has numerous advantages over the conventional joining methods and requires continuous improvements to overcome few shortcomings of the process. Over the decade, a lot of different tools were proposed to meet the weldment requirements and to overcome the defects formed during the welding. Since, each tool moves the weld material in a different way, therefore the current study considered seven different types of tool pin geometries and studied their effects on the material flow. The temperature dependent material properties were considered to conduct the thermal analysis. The material flow analysis of AA6061 weld plates was performed in ANSYS Fluent 14.5. The backing plate heat loss was also considered along with the convective heat loss in the simulation. The analysis performed was based on the established Finite Volume Method which considered the transient laminar flow of the material. A swirling motion of the material was observed in all the cases but it took place at different positions according to different tool pin geometries. A better material mixing was observed with tool having circular pin profile in comparison to the flat pin profiles. The viscosity distributions were also studied based on strain rates and temperature value. It was observed from the viscosity distribution that the conical pins were unable to mix the material properly near the probe tip region. Experiments were performed using conical pin tool to validate the model. The comparisons of thermal profiles showed good agreement regarding rising and cooling rate on both sides of the welds.