PENGARUH INTERLAYER ZN DENGAN VARIASI LAP JOINT TERHADAP STRUKTUR MIKRO DAN SIFAT MEKANIK SAMBUNGAN FSSW AA 1100

ABSTRAK
Aluminium banyak digunakan di industri otomotif, aerospace dan manufaktur karena kekuatan spesifiknya yang tinggi. Penelitian ini mengkaji pengaruh interlayer Zn dengan variasi lap joint terhadap penurunan terbentuknya hook defect. Material plat Al AA1100 dengan dimensi 125 × 40 × 3 mm yang disambung dengan mesin frais Optimum Maschinen Germany MT 100 (daya motor 2,2 kW, kecepatan spindle 1600 rpm) tool pin Ø14 mm, kecepatan putar 1600 rpm, kedalaman penetrasi 5 mm, pada variasi lebar lap joint 6 mm, 8 mm, 10 mm, dan 12 mm; pengujian tarik-geser dengan Universal Testing Machine (UTM) standar SNI 8389:2017. pengujian struktur mikro dilakukan menggunakan mikroskop Holland microscope serta etsa menggunakan larutan Modified Poulton Reagent (30 mL HCl, 40 mL HNO³, 2,5 mL HF, 42,5 mL H²O, dan 12 gram CrO³); hasil pengujian menunjukkan variasi lap 6 mm menghasilkan kekuatan tarik-geser tertinggi 12,32 MPa dan terendah 3,54 Mpa pada lap 10 mm. Struktur mikro memperlihatkan lapisan Zn yang masih utuh dan batas antarmuka Al-Zn yang jelas tanpa cacat void, munculnya cacat void di sekitar interface Al-Zn akibat aliran material yang kurang sempurna selama proses FSSW. Penambahan interlayer Zn dengan konfigurasi lap joint terbukti mampu meaningkatkan kualitas sambungan dan dapat meangatasi hook defect

ABSTRACT
Aluminum is widely used in the automotive, aerospace, and manufacturing industries due to its high specific strength. This study examines the effect of Zn interlayer with lap joint variation on the reduction of hook defect formation. The material used was an AA1100 Al plate with dimensions of 125 × 40 × 3 mm, joined using an Optimum Maschinen Germany MT 100 milling machine (motor power of 2.2 kW, spindle speed of 1600 rpm), a pinless tool with a diameter of 14 mm, a rotational speed of 1000 rpm, and a plunge depth of 5 mm, at lap joint widths of 6 mm, 8 mm, 10 mm, and 12 mm; the tensile-shear test was carried out using a Universal Testing Machine (UTM) according to the SNI 8389:2017 standard, while the microstructure examination was performed using a Holland microscope with etching using Modified Poulton Reagent solution (30 mL HCl, 40 mL HNO₃, 2.5 mL HF, 42.5 mL H₂O, and 12 grams CrO₃); the test results showed that the 6 mm lap variation produced the highest tensile-shear strength of 12.32 MPa, while the lowest value of 3.54 MPa was obtained at the 10 mm lap. The microstructure showed that the Zn layer remained intact with a clear Al-Zn interface boundary and no void defects, whereas void defects appeared around the Al-Zn interface due to imperfect material flow during the FSSW process. The addition of Zn interlayer with lap joint configuration was proven to improve joint quality and effectively mitigate hook defect formation
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