SILALAHI JOSE JAN FILDER, . (2025) PENGARUH KONSENTRASI GARAM (NaCl) SEBAGAI MEDIA QUECHING TERHADAP STRUKTUR MIKRO, KEKERASAN DAN LAJU KOROSI BAJA AISI 4140. Sarjana thesis, UNIVERSITAS NEGERI JAKARTA.
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Abstract
Penelitian ini membahas pengaruh variasi media pendingin terhadap transformasi fasa, peningkatan kekerasan, serta penurunan ketahanan material pada baja paduan AISI 4140. Spesimen diproses melalui perlakuan panas dengan metode pendinginan cepat menggunakan larutan natrium klorida pada tiga konsentrasi berbeda, yaitu 3,5%, 7%, dan 10,5% dengan suhu 1000°C kemudian ditahan selama 15 menit. Proses ini bertujuan memacu pembentukan struktur martensit yang rapat sehingga meningkatkan kekerasan. Pengamatan struktur mikro dilakukan menggunakan mikroskop optik, sedangkan uji kekerasan menggunakan metode vickers. Laju korosi diuji dengan metode weight loss dalam media korosif untuk mensimulasikan ketahanan material pada lingkungan agresif. Hasil penelitian menunjukkan konsentrasi garam yang lebih tinggi menghasilkan struktur martensit lebih halus, meningkatkan nilai kekerasan tetapi juga memicu tegangan sisa yang memperburuk daya tahan korosi. Dengan demikian, penentuan konsentrasi larutan pendingin yang tepat menjadi penting untuk menjaga keseimbangan antara peningkatan kekerasan dan penurunan laju kerusakan akibat korosi. Kata kunci: ketahanan material, martensit, pendinginan cepat, tegangan sisa. ***** This research discusses the effect of cooling media variation on phase transformation, hardness improvement, and material resistance reduction in AISI 4140 alloy steel, Specimens were processed through heat treatment with rapid cooling method using sodium chloride solution at three different concentrations, 3,5%, 7%, and 10,5% at 1000°C temperature and held for 15 minutes. This process aims to promote the formation of dense martensite structure to increase hardness. Microstructure observation was conducted using optical microscopy, while hardness testing used the Vickers method, Corrosion rate was tested using the weight loss method in corrosive media to simulate material resistance in aggressive environments. Research results. showed that higher salt concentrations produced finer martensite structure, increasing hardness values but also inducing residual stress that deteriorates corrosion resistance. Therefore, determining the appropriate cooling solution concentration becomes important to maintain balance between hardness improvement and reduction of corrosion-induced damage rate. Keywords: material resistance, martensite, quenching, residual stress
| Item Type: | Thesis (Sarjana) |
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| Additional Information: | 1). Dr. Ferry Budhi Susetyo, M.T., M.Si. ; 2). Dr. H. Syamsuir, M.T. |
| Subjects: | Teknologi dan Ilmu Terapan > Manufaktur |
| Divisions: | FT > D IV Teknologi Rekayasa Manufaktur |
| Depositing User: | Users 30733 not found. |
| Date Deposited: | 14 Aug 2025 06:24 |
| Last Modified: | 14 Aug 2025 06:24 |
| URI: | http://repository.unj.ac.id/id/eprint/61066 |
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