MUHAMAD RAIHAN, . (2026) ANALISIS VARIASI KUAT ARUS LAS SMAW TERHADAP JUMLAH CACAT LAS DAN LAJU KOROSI PADA PLAT SS400 6 MM UNTUK APLIKASI PLAT SHELL TANGKI SOLAR. Sarjana thesis, UNIVERSITAS NEGERI JAKARTA.
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Abstract
Penelitian ini bertujuan untuk menganalisis pengaruh variasi kuat arus pengelasan terhadap cacat las, laju korosi, nilai kekerasan, serta struktur mikro pada baja karbon rendah SS400 yang dilas menggunakan metode Shielded Metal Arc Welding (SMAW). Variasi arus yang digunakan adalah 70 A, 80 A, dan 90 A dengan kombinasi elektroda E7018 pada sambungan kampuh X sudut 60°. Pengujian dilakukan meliputi Magnetic Particle Test (MPT) untuk mendeteksi cacat permukaan dan bawah permukaan, uji laju korosi dengan metode weight loss dalam media Biosolar (B30) selama 168 jam, uji kekerasan menggunakan metode Vickers (HV), serta pengamatan struktur mikro melalui mikroskop optik. Hasil penelitian menunjukkan bahwa variasi arus pengelasan berpengaruh signifikan terhadap kualitas sambungan. Pada arus rendah (70 A), cacat yang terdeteksi lebih sedikit dan meliputi undercut, porositas, dan Crackssedangkan arus tinggi 80 dan 90 A menimbulkan cacat tambahan seperti Cracks permukaan akibat heat input berlebih. Laju korosi tertinggi diperoleh pada arus 90 A dengan nilai 0,084 mm/y, sedangkan laju korosi terendah terjadi pada arus 70 A sebesar 0,029 mm/y. Nilai kekerasan tertinggi ditemukan pada zona weld metal dengan arus 70 A sebesar 193,04 HV, dan terendah pada arus 90 A sebesar 174 HV. Analisis struktur mikro menunjukkan bahwa arus 70 A menghasilkan ukuran butir halus dengan distribusi ferrite–pearlite yang merata, sedangkan arus 90 A menyebabkan pertumbuhan butir kasar dan zona HAZ yang melebar. Dari hasil analisis keseluruhan dapat disimpulkan bahwa arus pengelasan 70 A memberikan hasil paling optimal dengan cacat minimal, struktur mikro halus, nilai kekerasan tinggi, serta ketahanan korosi terbaik terhadap paparan Biosolar (B30). Pengendalian parameter arus menjadi faktor utama dalam menjaga mutu dan keandalan sambungan las baja karbon rendah SS400, khususnya pada aplikasi tangki bahan bakar. Kata Kunci: Arus pengelasan, Kekerasan, Laju korosi, Magnetic Particle Test, Mikrostruktur, SMAW, SS400. ***** This study aims to analyze the effect of welding current variations on weld defects, corrosion rate, hardness value, and microstructure of low-carbon steel SS400 welded using the Shielded Metal Arc Welding (SMAW) method. The welding currents used were 70 A, 80 A, and 90 A, with E7018 electrodes applied to X-groove joints at a 60° bevel angle. The tests included the Magnetic Particle Test (MPT) for detecting surface and subsurface defects, corrosion testing using the weight loss method in Biosolar (B30) medium for 168 hours, hardness testing using the Vickers method (HV), and microstructural observations under an optical microscope. The results show that variations in welding current significantly affect weld quality. At a low current of 70 A, fewer defects were detected, mainly undercut, porosity, and spatter, whereas at 90 A, additional defects such as crater defects and surface cracks appeared due to excessive heat input. The highest corrosion rate occurred at 90 A with a value of 0.084 mm/y, while the lowest was at 70 A with 0.029 mm/y. The highest hardness value was recorded in the weld metal zone at 70 A (193 HV), and the lowest at 90 A (174 HV). Microstructural analysis revealed that welding at 70 A produced fine-grained structures with uniform ferrite–pearlite distribution, while higher current (90 A) caused coarse grain growth and a wider heat-affected zone (HAZ). Overall, the optimal welding current for SS400 steel was found to be 70 A, which resulted in minimal defects, finer microstructure, higher hardness, and superior corrosion resistance in the Biosolar (B30) environment. Therefore, controlling welding current is crucial to ensure mechanical integrity and corrosion resistance of low-carbon steel welds, especially in fuel tank applications.. Keywords: Corrosion rate, Hardness, Magnetic Particle Test, Microstructure, SMAW, SS400, Welding current
| Item Type: | Thesis (Sarjana) |
|---|---|
| Additional Information: | 1). Dr. Wardoyo, S.T., M.T. ; 2). Muhammad Fatihuddin, S.Pd., M.T. |
| Subjects: | Teknologi dan Ilmu Terapan > Teknik Pertambangan, Metalurgi Teknologi dan Ilmu Terapan > Teknik Energi Teknologi dan Ilmu Terapan > Manufaktur |
| Divisions: | FT > D IV Teknologi Rekayasa Manufaktur |
| Depositing User: | Muhamad Raihan |
| Date Deposited: | 04 Feb 2026 08:28 |
| Last Modified: | 04 Feb 2026 08:28 |
| URI: | http://repository.unj.ac.id/id/eprint/64018 |
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