PENGARUH KOMBINASI PERLAKUAN DC-LSND DAN PREHEATING TERHADAP SIFAT - SIFAT STATIS DAN MEKANIS PADA PENGELASAN FSW ALUMINIUM PADUAN SERI AA 5083-H116

Muhammad Irvan, Prof. M. Noer Ilman, S.T., M.Sc., Ph.d

2019 | Skripsi | S1 TEKNIK MESIN

Friction stir welding (FSW) merupakan proses pengelasan yang inovatif dikenal sebagai proses pengelasan kondisi padat (solid state). Proses pengelasan FSW ini tidak membutuhkan logam pengisi filler, sehingga komposisi hasil pengelasan yang didapatkan umumnya sama dengan komposisi logam induk, kecuali pengelasan pada logam yang berbeda. Penelitian ini bertujuan untuk mempelajari pengaruh perlakuan preheating, Dynamically Controlled - Low Stress No Distortion (DC-LSND), dan kombinasi perlakuan DC-LSND + preheating terhadap distorsi, sifat mekanis, dan sifat fatik sambungan las FSW. Bahan yang digunakan untuk pengelasan FSW adalah alumunium paduan seri AA5083-H116 dengan tebal 3 mm. Proses pengelasan dilakukan dengan variasi perlakuan preheating pada temperatur 200 derajat Celsius, DC-LSND, DC-LSND + preheating dan tanpa perlakuan. Kemudian pengujian dan pengamatan yang dilakukan meliputi data termal pengelasan, pengukuran distorsi, struktur mikro dan makro, pengukuran nilai kekerasan mikro Vickers, kekuatan tarik, dan perambatan retak fatik. Hasil penelitian menunjukkan bahwa perlakuan DC-LSND + preheating menunjukkan distorsi las yang lebih kecil dibandingkan perlakuan lain. Hasil kekuatan tarik paling tingi terdapat pada perlakuan DC-LSND. Perlakuan DC-LSND + preheating menunjukkan nilai kekerasan paling tinggi. Perlakuan DC-LSND + preheating juga terbukti menunjukkan laju perambatan retak fatik yang lebih rendah sehingga memiliki ketahanan fatik yang paling baik dibandingkan tanpa perlakuan.

Friction stir welding (FSW) is an innovative welding process known as a solid state welding process. This FSW welding process does not require filler material, so the final welding composition obtained is generally the same as the base metal composition, except when welding is carried out on two different metals. The aim of this study is to observe the effect of preheating treatment, Dynamically Controlled - Low Stress No Distortion (DC-LSND), and the combination of DC-LSND + preheating treatment on distortion, mechanical properties, and fatigue properties of FSW welded joints. The material used for FSW welding was aluminum alloy AA5083-H116 series with a thickness of 3 mm. The welding process was carried out with various preheating treatments at 200 degrees Celsius, DC-LSND, DC-LSND + preheating and without treatment. Then the tests and observations which were conducted include thermal welding data, measurement of distortion, micro and macro structure, measurement of Vickers micro hardness values, tensile strength, and fatigue crack propagation. The results showed that the DC-LSND + preheating treatment showed smaller weld distortion compared to other treatments. The result with highest tensile strength were found in the DC-LSND treatment. The DC-LSND + preheating treatment showed the highest hardness value. The DC-LSND + preheating treatment also showed a lower fatigue crack propagation rate so that it has the best fatigue resistance compared to the specimen without treatment.

Kata Kunci : friction stir welding (FSW), preheating, DC-LSND, laju perambatan retak fatik, AA5083-H116