PENGARUH PROSES PEMANASAN DENGAN VARIASI MEDIA PENDINGIN TERHADAPNILAI KEKERASAN DAN STRUKTUR MIKRO PADA BAJA KARBON SEDANG (EFFECT PROCESS OF HEATING WITH VARIATIONS OF COOLING MEDIA TO THE VALUE OF HARDNESS AND MICROSTRUCTURE THROUGH MEDIUM CARBON STEEL)

Sarimin, Dina Restia Ningrum (2013) PENGARUH PROSES PEMANASAN DENGAN VARIASI MEDIA PENDINGIN TERHADAPNILAI KEKERASAN DAN STRUKTUR MIKRO PADA BAJA KARBON SEDANG (EFFECT PROCESS OF HEATING WITH VARIATIONS OF COOLING MEDIA TO THE VALUE OF HARDNESS AND MICROSTRUCTURE THROUGH MEDIUM CARBON STEEL). Fakultas MIPA, Universitas Lampung.

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Abstrak

Telah dilakukan penelitian dengan variasi media pendingin terhadap nilai kekerasan dan struktur mikro pada baja pegas daun. Baja pegas daun dilakukan proses heat treatment pada temperatur 780oC selama 20 menit. Setelah itu baja langsung di dinginkan secara cepat (quenching)dengan media pendinginan yang berbeda yaitu udara, air, air garam, danoli. Sampel hasil perlakuan panas dan pendinginan dilakukan uji komposisi kimia, uji kekerasan, dan uji struktur mikro. Hasil penelitian menunjukkan bahwa pengujian komposisi kimia, baja pegas daun termasuk baja karbon sedang (0,57567% C),setelah proses heat treatment sampel tidak mengalami perubahan komposisi kimia. Hasil uji kekerasan nilai rata-rata tertinggi pada sampel yang menggunakan quenching air garam sebesar 61,25 HRC, nilai terendah pada sampel quenching udara sebesar 22,94 HRC, quenching air sebesar 59,45 HRC, tetapi pada sampel quenching air dan air garam terdapat keretakan pada permukaan dan quenching oli sebesar 58,54 HRC yang merupakan media pendingin yang relatif baik karena dapat meningkatkan nilai kekerasan tanpa mengalami keretakan pada sampel. Hasi lstruktur mikro pada sampel quenching udara menghasilkan butir-butir ferit dan perlit sedangkan pada sampel quenching air, air garam, dan oli menghasilkan butir-butir martensit dan austenite sisa. Semakin cepat laju pendinginan pada sampel, maka semakin halus butir-butir kristal dengan nilai kekerasan yang lebih tinggi, dan sebaliknya semakin lambat laju pendinginan pada sampel maka semakin besar butir-butir kristal dengan nilai kekerasan yang rendah. Kata kunci: Baja pegas daun, proses heat treatment,quenching, uji kekerasan,struktur mikro. (Research has been carried out with variations of the cooling media to hardness value and microstructure of leaf spring steel. Leaf spring steel was heated at temperature of 780°C for 20 minutes. Further process, steel was cooled quickly (quenching) with kinds of cooling medium, those were air, water, salt water, and oil. Samples of heating and cooling treatment were tested by chemical composition, hardness, and microstructure test. The results of chemical composition test showed that leaf spring steel include medium carbon steel (0,57567% C), after the heat treatment process samples were not occurred change of composition. The hardness testing revealed that highest average value in sample using salt water quenching HRC at 61,25, the lowest value in the sample using air quenching at 22,94 HRC, water quenching at 59,45 HRC and oil quenching at 58,54 HRC. Microstructure results in sample of air quenching produces grains of ferrite and pearlite, whereas the quenching samples of water , salt water, and oil produces grains of martensite and residual austenite. The faster of cooling rate in the samples generating the more finely crystalline grains with a higher hardness value, and conversely the slower of the cooling rate in the sample, producing the crystal grains were greater with low hardness values. Keywords:leaf spring steel, heat treatment, quenching, hardness, microstructure.)

Tipe Karya Ilmiah: Skripsi
Subyek: Q Science (General) > Q Science (General)
Q Science (General) > QP Physiology
Program Studi: Fakultas MIPA > Prodi Fisika
Depositing User: Farid Hambali Prihantoro, A.Md.
Date Deposited: 08 Jan 2014 05:17
Last Modified: 08 Jan 2014 05:17
URI: http://digilib.unila.ac.id/id/eprint/84

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