AL FAREL, FANDI AHMAD (2023) PENGARUH TEMPERATUR DAN WAKTU PENAHANAN INTERCRITICAL ANNEALING TERHADAP SIFAT MEKANIK BAJA FASA GANDA PADA BAJA JIS G3101 SS400. S1 thesis, Fakultas Teknik Universitas Sultan Ageng Tirtayasa.
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Abstract
With the development of technology in the automotive industry, the competition among global automotive manufacturers has become increasingly intense. They strive to create products that can meet market demands and influence consumer decisions in purchasing automobiles. This has prompted the steel industry to respond to new challenges, particularly the rapid development of Advanced High Strength Steels (AHSS). AHSS encompasses the following genetic types: dual-phase (DP), transformation-induced plasticity (TRIP), complex phase (CP), and martensitic steel (MART). Dual-phase steel has a microstructure consisting of a soft ferrite matrix and 10-40% hard martensite particles or martensite-austenite (M-A) constituents. Intercritical annealing is a heat treatment process in which the material is heated in the dual-phase region (α+γ). After undergoing intercritical annealing, the material undergoes quenching. Quenching is performed to increase the hardness and tensile strength of the material, which is related to the substitution of pearlite and some ferrite by austenite. This study aims to investigate the effect of temperature and holding time during intercritical annealing on the mechanical properties of dual-phase steel in JIS G3101 SS400 steel. In this research, hot-rolled steel with a thickness of 6 mm was used. The initial material was characterized using Optical Emission Spectrometer (OES) before undergoing intercritical annealing heat treatment. Intercritical annealing was performed at various temperatures of 730, 765, and 800°C, with holding times of 5, 10, and 15 minutes. Subsequently, metallographic observation, hardness testing, and tensile testing were conducted on the samples subjected to intercritical annealing. The results of the study include the formation of ferrite and martensite phases. Higher temperatures and longer holding times increase the volume fraction of martensite formed, thereby affecting its mechanical properties. However, there is a decrease in the volume fraction of martensite at 800°C due to reversible transformation. The optimal mechanical properties from this study were achieved at a temperature of 765°C with a holding time of 15 minutes, resulting in a tensile strength of 601 MPa, a volume fraction of martensite of 20.006% (optimal martensite structure proportion), and a hardness value of 198.7 HV. The activation energy (Q) obtained was 6.252504 J/mol.
| Item Type: | Thesis (S1) | |||||||||
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| Additional Information: | Seiring dengan perkembangan teknologi dalam dunia industri otomotif saat ini kian tumbuh dengan pesat sehingga persaingan diantara produsen otomotif dunia terjadi sedemikian ketat dalam menciptakan produk yang dapat memenuhi selera pasar serta mampu mempengaruhi keputusan konsumen dalam melakukan pembelian otomotif. Hal itu membuat industri baja memberikan respon terhadap tantangan baru yaitu perkembangan pesat baja kekuatan tinggi yang biasa disebut Advanced High Strength Steels (AHSS). Kategori AHSS mencakup tipe genetik berikut: fasa ganda (DP), plastisitas terinduksi transformasi (TRIP), fase kompleks (CP) dan baja martensit (MART). Baja fasa ganda memiliki struktur mikro yang terdiri dari matriks ferit lunak dan 10-40% partikel martensit keras atau martensit-austenit (M-A). Intercritical annealing merupakan proses heat treatment yang mana material dipanaskan di daerah fasa ganda (α+γ). Setelah melalui proses intercritical annealing, dilakukan proses quenching. Proses quenching, dilakukan agar material mengalami peningkatan kekerasan dan kekuatan tarik yang berhubungan dengan substitusi perlit dan sejumlah ferit oleh austenite. Penelitian ini bertujuan untuk mengetahui pengaruh temperatur dan waktu penahanan Intercritical Annealing terhadap sifat mekanik baja fasa ganda pada baja JIS G3101 SS400. Dalam penelitian ini menggunakan baja canai panas dengan ketebalan 6 mm, kemudian material awal di karakterisasi menggunakan OES (Optical Emission Spectrometer) sebelum diberi perlakuan panas Intercritical Annealing. Proses Intercritical Annealing dilakukan menggunakan variasi temperatur 730, 765, dan 800°C, serta variasi waktu penahanan selama 5, 10, dan 15 menit. Setelah itu dilakukan pengamatan metalografi, pengujian kekerasan, dan pengujian tarik terhadap sampel yang telah dilakukan Intercritical Annealing. Hasil penelitian yang telah dilakukan antara lain seperti terbentuknya fasa ferit dan martensit, semakin tinggi temperatur dan waktu penahanan yang diberikan akan meningkatkan fraksi volume martensit yang terbentuk sehingga mempengaruhi sifat mekaniknya. Namun terjadi penurunan fraksi volume martensit pada temperatur 800°C akibat terjadinya transformasi reversibel. Hasil sifat mekanik yang optimal dari penelitian ini dihasilkan pada temperatur 765°C dengan waktu penahanan 15 menit dengan menghasilkan nilai tensile strength sebesar 601 MPa dan fraksi volume martensit sebesar 20,006% (struktur martensit proporsi optimal) serta nilai kekerasan 198,7 HV. Sedangkan untuk energi aktivasi (Q) yang dihasilkan sebesar 6,252504 J/mol. | |||||||||
| Subjects: | T Technology > TS Manufactures | |||||||||
| Divisions: | 03-Fakultas Teknik 03-Fakultas Teknik > 27201-Jurusan Teknik Metalurgi |
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| Depositing User: | Mr. Fandi Ahmad Al Farel | |||||||||
| Date Deposited: | 21 Jul 2023 10:34 | |||||||||
| Last Modified: | 21 Jul 2023 10:34 | |||||||||
| URI: | http://eprints.untirta.ac.id/id/eprint/27021 |
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