English:
Analysis of Data from Friction Stir Welds in Aluminum

Kevin Colligan, Concurrent Technologies Corporation Johnstown, PA, USA

In the present work, welding procedures for friction stir welding (FSW) of aluminum alloys were collected from published and unpublished welding procedures, permitting analysis with a diverse collection of alloys, material thickness, tool designs and machine parameters. Broad trends were observed with respect to tool design and flow stress in the weld zone. The data also gave insight into diversions from broad trends brought about by certain conditions.

Spindle torque is a key variable in FSW since it is directly related to heat generation. The compiled data set permitted analysis of spindle torque from a wide variety of welding conditions. To compare heat generation from diverse welding procedures, the torque data and welding tool geometries were used to calculate the average contact shear stress during welding, which was plotted against the average surface velocity of the tool surfaces. The results gave insight into the effects of welding speed, rotational speed and alloy on the average flow stress. The results also suggested evidence of the exhaustion of heat generation at high tool surface velocities and a possible effect of initial workpiece temper on conditions during welding.