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Satrio Herbirowo
Pusat Penelitian Metalurgi dan Material - LIPI
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Studi Pengaruh Paduan Cr/Mo dengan Waktu Perendaman Cryogenic Treatment terhadap Sifat Keras, Tangguh, Tahan Abrasif, dan Struktur Mikro Baja Ni berbasis Laterit Alfa Sendya Hayu Marzuki; Satrio Herbirowo; Bintang Adjiantoro; Yeni Muriani Zulaida; Efendi Mabruri
Jurnal Metal Indonesia Vol 42, No 1 (2020): Metal Indonesia
Publisher : Balai Besar Logam dan Mesin

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (404.436 KB) | DOI: 10.32423/jmi.%Y.v%v.%p

Abstract

Grinding ball merupakan salah satu komponen dari industri tambang dan pengolahan mineral yang mempengaruhi biaya produksi. Kebutuhan grinding ball dalam negeri saat ini masih bergantung pada produk impor. Pemilihan baja berbasis laterit karena cadangan laterit di Indonesia sangat melimpah, selain itu baja laterit sudah memiliki kandungan nikel dimana unsur paduan tersebut baik untuk meningkatkan kekerasan yang dibutuhkan pada grinding ball. Namun tingkat kekerasan baja berbasis laterit yang digunakan pada penelitian ini belum memiliki nilai yang cukup untuk digunakan sebagai material grinding ball. Oleh karena itu, pada penelitian ini dilakukan proses cryogenic treatment dengan variasi waktu perendaman 10, 60, dan 360 menit serta menggunakan perbedaan komposisi paduan Cr dan Mo kemudian dilakukan pengujian kekerasan, ketahanan aus, ketangguhan dan analisis struktur mikro. Berdasarkan hasil yang diperoleh menunjukkan bahwa kekerasan setelah perlakuan mengalami peningkatan signifikan dari 17 menjadi 33,55 HRC. Selain itu, ketahanan abrasif setelah perlakuan juga meningkat seiring dengan penambahan waktu perendaman dari 0,000603 menjadi 0,000475 mg/cm2·putaran. Peningkatan tersebut terjadi karena adanya peningkatan persentase martensit pada sampel. Nilai kekerasan dan ketahanan aus terbaik terdapat pada sampel dengan paduan CrMo pada waktu perendaman 360 menit yaitu 44,1 HRC dan 0,000475 mg/cm2·putaran. Sehingga pada penelitian ini menunjukkan bahwa waktu perendaman cryogenic treatment dan komposisi paduan Cr dan Mo berpengaruh terhadap kekerasan, ketahanan abrasif serta ketangguhan baja nikel berbasis laterit. Grinding ball is a component of the mining and mineral processing industry that affects production costs. Grinding ball needs in Indonesia still depend on imported products. Laterite-based steel is chosen because of the resource of laterite in Indonesia are very abundant, besides laterite steel has nickel content which is great for increasing the hardness that needed in grinding ball. However, the hardness of Ni laterite steel used in this study does not have enough hardness to be used as a grinding ball material. Therefore, in this study cryogenic treatment was carried out with variations in soaking time during10, 60 and 360 minutes and also using differences in the alloying composition of Cr/Mo then performed characterization of hardness, abrasive resistance, toughness and microstructure analysis. Based on the results obtained showed that hardness after treatment increases with increasing soaking time from 17 to 33,55 HRC significantly. In addition, abrasive resistance after treatment also increases with increasing soaking time from 0,000603 to 0,000475 mg/cm2.cycle. This increase occurred because of an increase in the percentage of the martensite phase in the sample. The optimum value of hardness and wear resistance is found in samples with CrMo alloy at 360 minutes soaking time, which is 44.1 HRC and 0.000475 mg/cm2·cycle. This study shows that cryogenic treatment soaking time and Cr and Mo alloy composition affect the hardness, abrasive resistance, and toughness of laterite nickel-based steel.
OPTIMIZATION OF MECHANICAL STRENGTH AND MICROSTRUCTURE ON AUSTEMPERING ZINC HEAT TREATMENT IN LATERITIC NICKEL STEELS Satrio Herbirowo; Setyo Hartadi; Rahmat D. Widodo; Bintang Adjiantoro
Jurnal Sains Materi Indonesia Vol 20, No 4: JULY 2019
Publisher : Center for Science & Technology of Advanced Materials - National Nuclear Energy Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (872.316 KB) | DOI: 10.17146/jsmi.2019.20.4.4660

Abstract

The development of lateritic steel is currently being discussed by various research institutions. It is not separated from the potential of laterite-based steel into national steel. This research using austempering heat treatment process with holding time variation for 30, 60, and 90 minutes with Zn (Zinc) element from melting ingot with 90% purity for cooling media. The characterization of laterite steel is done by hardness testing, impact resistance, microstructure, scanning electron microscopy, and energy dispersive spectroscopy. The results showed that the impact resistance value decreased 8.46%, which was initially 209 J to 191.3 J. Besides, the hardness value increased 36, 58% of which was originally 164 HV to 224 HV. Judging from its physical properties, the microstructure formed bainite ferrite perlite at holding time 90 minutes while the fracture is included into the ductile fracture because there are dimple holes showed dark and opaque
Karakteristik Sifat Mekanik dan Struktur Mikro Baja Laterit Paduan Ni-Cr-Mn Hasil Tempa Panas Dengan Variasi Beban Tempa [Mechanical Properties and Microstructure Characterization of Ni-Cr-Mn Alloys Lateritic Steel as a Result of Hot Forging with Variated Satrio Herbirowo; Bintang Adjiantoro; Fatayalkadri Citrawati
Metalurgi Vol 33, No 1 (2018): Metalurgi Vol. 33 No. 1 April 2018
Publisher : National Research and Innovation Agency (BRIN)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (416.037 KB) | DOI: 10.14203/metalurgi.v33i1.338

Abstract

NiCrMn alloy lateritic steel has a potential as an alternative for steel raw material that has high toughness and substitute the commercial AISI 4340 steel. This research is conducted to know the characteristics of lateritic steels according to AISI 4340 standard from chemical composition, mechanical properties, and microstructure after hot forging process with variety of loads and oil as cooling media. The hot forging process was carried out at temperature of 1200 °C using 3 variety of forging loads: 50, 75, and 100 tons. The forged NiCrMn alloy lateritic steel was characterized by chemical composition analysis with OES (optical emission spectrometer), metallographic observation using OM (optical microscopy), Charpy impact test, and hardness Rockwell C. The result of chemical composition analysis showed that NiCrMn alloy lateritic steel had chemical composition in accordance to AISI 4340 with modification of Ni, Cr, and Mn elements equal to (wt.%) 1.8; 1.71; 1.87. The characteristics of NiCrMn alloy lateritic steel showed that the hardness and toughness increased when the % reduction improved. In reduction percentage of 31.02% it was obtained hardness value and energy absorb equal to 61.21 HRC and 0.166 J/mm2, with structure formed was martensit phase. However, at a higher reduction percentage of 31.72%, the hardness and impact strength values decreased to 58.56 HRC and 0.19 J/mm2. This occured because of the structure formed in the NiCrMn alloy lateritic steel was a martensite phase with retained austenite. AbstrakBaja 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 yaitu sifat kekerasan, ketangguhan, struktur mikro, dan struktur patahan baja laterit dengan variasi beban pada proses penempaan panas (hot forging). Penempaan panas menggunakan 3 variasi beban tempa yaitu 50, 75, dan 100 ton serta bahan awal (As Cast) dengan 1 kali penempaan pada temperatur pemanasan 1200°C. Penempaan panas menghasilkan reduksi As Cast (0%), 50 ton (18.06%), 75 ton (31.02%), dan 100 ton (31.72%). Hasil pengujian karakterisasi material menunjukkan bahwa nilai kekerasan tertinggi dan nilai impak tertinggi pada reduksi 31.02% sebesar 61.21 HRC dan 0.21 Joule/mm2. Struktur mikro yang terbentuk pada As Cast adalah ferit dan perlit sedangkan pada hasil penempaan panas adalah bainit. Hasil struktur patahan menggunakan Scanning Electron Microscope menunjukkan bahwa ukuran butir semakin halus dan pipih seiring bertambahnya beban tempa panas.
Analisa Strukturmikro dan Pengaruhnya terhadap Sifat Mekanis Batangan Rel Tipe R54 [Microstructure Analysis and Its Effect to Mechanical Properties of Rail Track Type R54] Robby Dwiwandono; Leksono Firmansyah; Satrio Herbirowo; M Yunan Hasbi; Fatayalkadri Citrawati
Metalurgi Vol 32, No 2 (2017): Metalurgi Vol. 32 No. 2 Agustus 2017
Publisher : National Research and Innovation Agency (BRIN)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1112.16 KB) | DOI: 10.14203/metalurgi.v32i2.340

Abstract

This study was conducted to observe the mechanical properties and microstructures of two rail tracks type R54 used in Indonesia, which produce in Germany (rail steel G) and China (rail steel C). During its application, it is necessary for rail track to have high toughness to bear the dynamic load from wheel movement.  In this study, several examinations and observations have been made, which comprise OES chemical composition analysis, metallography by using OM, tensile test, and micro Vickers hardness test. The OES chemical composition result shows that both rail tracks belong to Fe-C-Mn rail steels, in which, rail steel G has higher Zr micro alloy content than rail steel C. These differences do not significantly affect their tensile strength, which are 1050 MPa and 1044 MPa for rail steel G and rail steel C, respectively. Moreover, both samples were observed to have elongation of 13%. The difference in micro alloys, specifically Zr, may influence the hardness of the samples through precipitate strenghtening. The average hardness in the body part of the tracks show that rail steel G has slightly higher hardness value compare to rail steel C. It is 341 HV for rail steel G and 324 HV for rail steel C. This hardness difference was also found between the head part and the body part of both rail tracks. In the head part, the area near the edge of the rail tracks e has an average hardness of 452 HV for rail steel G and 423 HV for rail steel C. These values are higher than the hardness value of the body part of both rail tracks. The difference in hardness of the body part and the head part might be due to the phases in their microstructure, which observed to be dominated by pearlite.AbstrakPenelitian ini dilakukan dengan tujuan untuk mengetahui sifat mekanik dan struktur mikro dari beberapa jenis batangan rel bertipe R-54 yang digunakan di Indonesia, yaitu yang berasal dari Jerman (kode sampel G) dan Cina (kode sampel C). Dalam aplikasinya, ketangguhan tinggi diperlukan agar material batangan rel mampu meredam atau menahan beban roda kereta api saat berjalan. Dalam penelitian ini, beberapa pengujian telah dilakukan, antara lain pengujian komposisi kimia dengan optical emission spectrometer (OES), pengamatan metalografi dengan optical microscope (OM), pengujian keuatan tarik serta uji keras Micro Vickers. Dari hasil pengujian komposisi kimia didapatkan bahwa sampel G memiliki unsur pemadu mikro Zr lebih besar dari sampel C. Perbedaan komposisi kimia ini tidak mempengaruhi besarnya kekuatan tarik pada kedua sampel secara signifikan, dimana dari hasil pengujian tarik didapatkan nilai kekuatan tarik untuk sampel G sebesar 1050 MPa dan sampel C sebesar 1044 MPa dengan nilai elongasi yang sama yaitu sebesar 13%. Pengaruh dari perbedaan kandungan unsur-unsur pemadu, dalam hal ini Zr, dimungkinkan dapat mempengaruhi nilai kekerasan rata-rata dari kedua sampel melalui pembentukan presipitat, dimana dari hasil pengujian kekerasan pada bagian badan rel, secara keseluruhan, sampel G memiliki nilai kekerasan rata-rata lebih tinggi dibandingkan sampel C, yaitu 341 HV (sampel G) dan 324 HV (sampel C). Perbedaan pada nilai kekerasan juga ditunjukkan untuk bagian kepala dan bagian badan rel dari kedua sampel. Pada bagian kepala, terutama diseputaran bagian permukaannya, memiliki nilai kekerasan rata-rata yang lebih tinggi, yaitu 452 HV (sampel G) dan 423 HV (sampel C), dibandingkan dengan kekerasan rata-rata pada bagian badan, baik di area tepi maupun tengah. Perbedaan kekerasan yang terjadi antara bagian kepala dan badan rel pada kedua sampel salah satunya dipengaruhi oleh struktur mikronya, yang didominasi oleh fasa perlit.
Co-Authors Alfa Sendya Hayu Marzuki Bintang Adjiantoro Bintang Adjiantoro Bintang Adjiantoro Efendi Mabruri Fatayalkadri Citrawati Fatayalkadri Citrawati Leksono Firmansyah M Yunan Hasbi Rahmat D. Widodo Robby Dwiwandono Setyo Hartadi Yeni Muriani Zulaida