Dissimilar friction stir welds in AA5083-AA6082. Part I: Process parameter effects on thermal history and weld properties

The aim of this study was to explore the so-called processing window, within which good-quality welds can be produced, for the friction stir welding of AA5083 to AA6082. To that end a systematic set of nine instrumented welds were made using rotation speeds of 280, 560, and 840 rpm and traverse speeds of 100, 200, and 300 mm/min with AA5083 on the advancing side and another nine with the materials reversed. For comparison a smaller series of AA5083-AA5083 and AA6082-AA6082 welds were also made. Thermocouple measurements, tool torque, extent of material mixing, and macrostructural observations all indicate that the temperature under the tool is more strongly dependent on the rotation than the traverse speed. It was found that in the current case, the power (energy/s) and heat input (energy/mm) do not correlate simply with the weld temperature. As a result, such metrics may not be suitable for characterizing the conditions under which welds are produced.