Ahmad, Husain Syah (2026) Pengaruh Arus Dan Flow-rate Gas Pelindung Pada Gas Metal Arc Welding Terhadap Sifat Mekanik Dan Struktur Mikro JIS G3101 SS400 Untuk Aplikasi Underframe Kereta. Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Di zaman sekarang, dengan berkembangnya transportasi lokomotif, dibutuhkan kualitas lasan yang baik untuk menghasilkan fabrikasi yang optimal, khususnya pada center-sill kereta yang mendapat beban tarik dan tekan. Penelitian ini bertujuan untuk menganalisis pengaruh variasi arus dan laju aliran gas pelindung terhadap sifat mekanik dan struktur mikro sambungan baja SS400 menggunakan proses Gas Metal Arc Welding (GMAW). Material SS400 dipilih karena memiliki sifat mampu las yang baik, kekuatan sedang, dan banyak digunakan dalam konstruksi maupun industri transportasi. Parameter pengelasan yang divariasikan adalah arus 200, 250, dan 300 A serta laju aliran gas 15 dan 20L/menit, dengan gas pelindung campuran Argon–CO₂ (82% Ar dan 18% CO₂) dan filler metal ER80S-G. Hasil penelitian menunjukkan bahwa peningkatan arus pengelasan meningkatkan heat input sehingga memengaruhi transformasi struktur mikro pada daerah weld metal (WM), heat-affected zone (HAZ), dan base metal (BM). Struktur mikro weld metal didominasi oleh acicular ferrite dan bainitic ferrite, sedangkan HAZ didominasi oleh polygonal ferrite dan bainitic ferrite, serta base metal terdiri atas polygonal ferrite dan pearlite. Peningkatan arus menghasilkan pertumbuhan butir akibat laju pendinginan yang lebih lambat, namun keberadaan acicular ferrite pada weld metal tetap memberikan peningkatan kekerasan. Variasi arus 200A menghasilkan nilai kekerasan tertinggi pada weld metal sebesar 251 HV, sedangkan variasi 250A 20L/menit memberikan kombinasi sifat mekanik terbaik dengan nilai ultimate tensile strength (UTS) tertinggi sebesar 630,5 MPa. Peningkatan flow rate gas pelindung dari 15L/menit menjadi 20L/menit mampu mencegah masuknya pengotor pada lasan, sehingga mengurangi potensi cacat.
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With the advancement of railway transportation, high-quality welded joints are essential to ensure optimal fabrication, particularly for railway center sills, which are subjected to both tensile and compressive loads. This study aims to analyze the effects of welding current and shielding gas flow rate on the mechanical properties and microstructure of SS400 steel welded joints produced using the Gas Metal Arc Welding (GMAW) process. SS400 steel was selected due to its excellent weldability, moderate strength, and widespread application in construction and transportation industries. The welding parameters investigated were currents of 200 A, 250 A, and 300 A, combined with shielding gas flow rates of 15 and 20 L/min. An Ar–CO₂ shielding gas mixture (82% Ar and 18% CO₂) and ER80S-G filler metal were employed throughout the welding process. The results indicate that increasing the welding current increases the heat input, thereby influencing the microstructural transformations in the weld metal (WM), heat-affected zone (HAZ), and base metal (BM). The weld metal was predominantly composed of acicular ferrite and bainitic ferrite, whereas the HAZ was mainly characterized by polygonal ferrite and bainitic ferrite. The base metal consisted primarily of polygonal ferrite and pearlite. Higher welding currents promoted grain growth due to the slower cooling rate; however, the presence of acicular ferrite in the weld metal continued to contribute to increased hardness. The highest weld metal hardness, reaching 251 HV, was obtained at a welding current of 200 A. Meanwhile, the combination of a 250 A welding current and a shielding gas flow rate of 20 L/min produced the best mechanical performance, achieving the highest ultimate tensile strength (UTS) of 630.5 MPa. Furthermore, increasing the shielding gas flow rate from 15 to 20 L/min effectively prevented atmospheric contamination during welding, thereby reducing the likelihood of welding defects
| Item Type: | Thesis (Other) |
|---|---|
| Uncontrolled Keywords: | GMAW, Gas Pelindung, SS400, Sifat Mekanik, Struktur Mikro GMAW, SS400, shielding gas, mechanical properties, microstructure |
| Subjects: | T Technology > TF Railroad engineering and operation T Technology > TS Manufactures > TS176 Manufacturing engineering. Process engineering (Including manufacturing planning, production planning) T Technology > TS Manufactures > TS183 Manufacturing processes. Lean manufacturing. T Technology > TS Manufactures > TS205 Metals--Heat treatment. T Technology > TS Manufactures > TS227 Welding. |
| Divisions: | Faculty of Industrial Technology and Systems Engineering (INDSYS) > Material & Metallurgical Engineering > 28201-(S1) Undergraduate Thesis |
| Depositing User: | Husain Syah Ahmad |
| Date Deposited: | 24 Jul 2026 01:11 |
| Last Modified: | 24 Jul 2026 01:11 |
| URI: | http://repository.its.ac.id/id/eprint/137374 |
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