Pengaruh Geometri Tools Proses Friction Stir Welding (FSW) Terhadap Kekuatan Tarik, Struktur Makro Dan Kekerasan Pada Sambungan Butt Joint AA7075 = The Influence of Tool Geometry in the Friction Stir Welding (FSW) Proses on Tensile Strength, Macro Structure, and Hardness of AA7075 Butt Joints