Garuda - Garba Rujukan Digital

Satrio Herbirowo

Unknown Affiliation

Author-ID : 6151747

Computer Science & IT Electrical & Electronics Engineering Energy Engineering Industrial & Manufacturing Engineering Materials Science & Nanotechnology

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THE EFFECT OF ECAP PROCESSING TO HARDNESS, SURFACE MORPHOLOGI, AND CORROSION RESISTANCE OF 6061 ALUMINIUM ALLOYS Vinda Puspasari; I. Nyoman Gede P. A.; Efendi Mabruri; Satrio Herbirowo; Edy Priyanto Utomo
Metalurgi Vol 36, No 2 (2021): Metalurgi Vol. 36 No. 2 Agustus 2021
Publisher : National Research and Innovation Agency (BRIN)

Al-Mg-Si alloys (6xxx) has been widely used as structural materials in building and vehicles because of its excellent strength and corrosion resistance. The improvement of fine grain microstructure which can increase mechanical and physical properties become an interesting field in recent research.. Equal channel angular press is the most promising method to apply severe plastic deformation (SPD) which can produce ultra-fine grain in the bulk material without residual porosity. This study presents some experiments results on the effect of ECAP number of passes variation to the hardness, microstructure, and corrosion behaviour of Al 6061 alloys. The samples were annealed in the furnace with argon gas environment at 530°C for 4 hours and then immersed in liquid nitrogen for 5 minutes before ECAP process. The ECAP process was done with Bc route using dies with 120° of internal channel angle and pass variation of 1, 2, 3, and 4. The optimum hardness is 107.58 HRB in Al 6061 samples with 3 passes of ECAP. The increasing ECAP number of passes leads to a significant grain size reduction from 0 way pass, the grain size is around 10 µm, while for a 4 way pass, the grain size is around 2.5 µm. The corrosion resistance of Al 6061 alloys increased with the increasing number of passes in ECAP process.

Studi Variasi Suhu Tahan pada Saat Proses Laku Panas Baja Paduan Berfasa Ganda Ni-Laterit Satrio Herbirowo; Saefudin Saefudin; Bintang Adjiantoro
Jurnal Teknologi Bahan dan Barang Teknik Vol 8, No 1 (2018)
Publisher : Balai Besar Bahan dan Barang Teknik

This research was aimed to study the effect of variations in the holding temperature on Ni-laterite steel at 800°C and the holding time of one hour with cooling treatment variation on water quench media. After holding temperature of 800°C, three specimens were reheated at 300, 500, and 700°C simultaneously. After the first heating at 800°C, the specimen had a hardness of 60.98 HRC, and composed of 82.04% martensite phase fraction and 18.51% ferrite phase fraction. After the second heating at 300°C, the specimen had a hardness of 21.36 HRC, and composed of 66.11% pearlite and 33.89% fine-grain ferrite. Large grain pearlite changed to dendritic due to solidification and phase transformation. Morphological characterization using Scanning Electron Microscopy and Energy Dispersive X-Ray resulted in clear grain boundary as well as martensite phase shape. Ni/Fe alloyed element dispersed in all sample sections.Penelitian ini ditujukan untuk mempelajari pengaruh variasi suhu tahan pada baja Ni-laterit yang dipanaskan pada temperatur 800oC dengan waktu tahan 1 jam dan media pendinginan berupa air. Setelah pemanasan dan pendinginan tersebut, spesimen kembali dipanaskan dengan temperatur penahanan bervariasi 300, 500, 700oC secara simultan. Pada spesimen dengan pemanasan pertama, didapatkan nilai kekerasan 60,98 HRC dan fasa yang terbentuk adalah 82,04% martensit dan 18,51% ferit. Pada pemanasan 300oC didapatkan nilai kekerasan 21,36 HRC dan fasa yang terbentuk adalah 66,11% perlit dan 33,89% ferit halus. Perlit kasar membentuk struktur dendritik, didapatkan karena solidifikasi dan transformasi fasa. Karakterisasi morfologi menggunakan SEM dan EDS menunjukkan struktur batas butir yang jelas beserta bentuk fasa martensit dan elemen paduan Ni/Fe tersebar merata pada sampel.

Pengaruh Sifat Mekanik dan Morfologi pada Baja Laterit Hasil Tempa dengan Variasi Perlakuan Panas Satrio Herbirowo; Bintang Adjiantoro
Jurnal Teknologi Bahan dan Barang Teknik Vol 7, No 1 (2017)
Publisher : Balai Besar Bahan dan Barang Teknik

Lateritic steel is a steel based of nickel laterite ore. Nickel laterite ore is usually ignored by miners due to economical factors and more looking for a nickel that under limonite layers. The purpose of this research is to determine the characteristics of the laterite steels with forging process and the heat treatment variation to its mechanical and morphological properties. The starting materials of lateritic cast steel with FeMn and FeMo based alloys by ARMOX 500T standardization. Hot forging process at recrystallization temperature of 1100 °C and loads 100 tons with variations of heat treatment such as oil quench; martempering temperature 100; 200; 300; and 400 °C. Then characterized of chemical composition test, tensile testing, hardness, and morphology of microstructure using Scanning Electron Microscope (SEM). The characterization test results showed that the highest hardness value and highest tensile strength value in the quench oil heat treatment were 520.8 HV and 1521 N / mm2. The morphological observations of microstructure showed that the phase transformation of the ferrite-perlite into martensite (quench oil) and bainite (martempering) and failure analysis results in non-HT samples showed grain boundary fractures and confirmed ductile behaviour with dimple fracture, for oil quench has a brittle fracture and initiation failure with a large cleavage-shaped size. The martempering treatment has smaller grain size, solid and smooth. Fractures tend to be more ductile than non-HT samples, and fine dimple shaped and are predicted to have the highest toughness properties. Baja laterit merupakan baja berbahan dasar bijih nikel laterit. Bijih nikel laterit biasa diabaikan penambang karena faktor ekonomis dan lebih mencari nikel yang berada dibawah lapisan limonit. Tujuan penelitian ini adalah mengetahui karakteristik baja laterit dengan proses tempa dan variasi perlakuan panas terhadap sifat mekanik dan morfologinya. Bahan awal baja laterit hasil cor perpaduan FeMn dan FeMo mengacu standar baja ARMOX 500T, selanjutnya mengalami proses tempa panas pada suhu rekristalisasi 1100 °C dan pembebanan 100 ton dengan beberapa variasi perlakuan panas antara lain quench media oli; martempering suhu 100; 200; 300; dan 400 °C. Karakterisasinya meliputi uji komposisi kimia, pengujian tarik, kekerasan, dan morfologi struktur mikro menggunakan Scanning Electron Microscope (SEM). Hasil pengujian menunjukkan bahwa nilai kekerasan tertinggi dan nilai kekuatan tarik tertinggi pada perlakuan panas quench oli adalah 520,8 HV dan 1521 N/mm2. Hasil pengamatan morfologi struktur mikro menunjukkan bahwa terjadi transformasi fasa dari ferit-perlit menjadi martensit (quench oli) dan bainit (martempering) serta hasil analisis patahan pada sampel non-HT menunjukkan patahan batas butir dan cenderung bersifat ulet dengan bentuk patahan dimple, untuk sampel quench oli memiliki patahan getas dan inisiasi patahan dengan ukuran besar berbentuk cleavage. Perlakuan martempering memiliki ukuran butir lebih kecil, padat dan halus. Bentuk patahan cenderung lebih ulet dibandingkan sampel non-HT, dan berbentuk dimple halus serta diprediksi memiliki sifat ketangguhan paling tinggi.

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