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THE INFLUENCE OF HEAT TREATMENT ON MICROSTRUCTURE AND MECHANICAL STRENGTH OF LATERITIC NICKEL STEEL Satrio Herbirowo; Bintang Adjiantoro
Widyariset Vol 2, No 2 (2016): Widyariset
Publisher : Pusbindiklat - LIPI

Indonesia has abundant resources of lateritic nickel ore and coal. However, this resource has not been considered as a main raw material in the Indonesian steel industry. Therefore, this study are aimed to investigate several aspects of lateritic nickel intrinsic propertiesand its potency through heat treatment process. Nickel laterite steels are usually used for bridge and building construction steel. Their properties can be improved in various ways, such as by conducting temper heat treatment. This research reported the influences of heat treatment on microstructure and mechanical strength in nickel laterite steel. Samples were austenitized at 900ºC and subsquently tempered at 100 ºC, 200 ºC, 300 ºC, 400 ºC, 500 ºC, and 600ºC. Metallographic observation was conducted by using an optical microscope meanwhile mechanical strength were conducted by tensile test and surface hardness. The results showed evolution of mictrostructure in nickel laterite steel after heat treatment. The microstructure formed consisted of martensite temper. The presence of inclusion can affect brittle behavior of the lateritic nickel. The optimum tempering temperature was 200 ºC. The result of Scanning Electron Microscope (SEM) fractography showed the dimple and intergranular fracture has caused a more ductile and mechanical behavior which is compatible with construction steels standard.

THE INFLUENCE OF HEAT TREATMENT ON MICROSTRUCTURE AND MECHANICAL STRENGTH OF LATERITIC NICKEL STEEL Satrio Herbirowo; Bintang Adjiantoro
Widyariset Vol 2, No 2 (2016): Widyariset
Publisher : Pusbindiklat - LIPI

Indonesia has abundant resources of lateritic nickel ore and coal. However, this resource has not been considered as a main raw material in the Indonesian steel industry. Therefore, this study are aimed to investigate several aspects of lateritic nickel intrinsic propertiesand its potency through heat treatment process. Nickel laterite steels are usually used for bridge and building construction steel. Their properties can be improved in various ways, such as by conducting temper heat treatment. This research reported the influences of heat treatment on microstructure and mechanical strength in nickel laterite steel. Samples were austenitized at 900ºC and subsquently tempered at 100 ºC, 200 ºC, 300 ºC, 400 ºC, 500 ºC, and 600ºC. Metallographic observation was conducted by using an optical microscope meanwhile mechanical strength were conducted by tensile test and surface hardness. The results showed evolution of mictrostructure in nickel laterite steel after heat treatment. The microstructure formed consisted of martensite temper. The presence of inclusion can affect brittle behavior of the lateritic nickel. The optimum tempering temperature was 200 ºC. The result of Scanning Electron Microscope (SEM) fractography showed the dimple and intergranular fracture has caused a more ductile and mechanical behavior which is compatible with construction steels standard.

Pengaruh Doping Nikel dan Suhu Sinter pada Pembuatan Kawat Superkonduktor Magnesium Diborida Satrio Herbirowo; M Nur Hanafi; Agung Imaduddin; Edy Priyanto Utomo; Hendrik Hendrik; Aditya Trenggono; Erlina Yustanti
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 10, No 2 (2020): October
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v10i2.34984

Peningkatan sifat superkonduktor MgB2 melalui penambahan doping telah banyak dilakukan. Meskipun begitu, pembuatan kawat superkonduktor MgB2 belum secara optimal dihasilkan akibat porositas yang terbentuk dari struktur lapis MgB2. Tujuan penelitian ini adalah untuk menganalisis efek penambahan doping nikel terhadap nilai kristalinitas dan kepadatan serta temperatur optimum dalam sintesis kawat superkonduktor berbasis MgB2. Variabel proses pada sampel yang digunakan yaitu variasi persen berat doping Nikel dan temperatur sintering. Karakterisasi yang digunakan meliputi Xray Diffraction (XRD), Scanning Electron Micoscope-Energy Dispersive Spectroscopy (SEM-EDS), dan Cryogenic Magnet. Pembuatannya menggunakan proses metalurgi serbuk dengan metode powder in tube secara in-situ dan manufaktur pengerolan kawat. Pengerolan dilakukan reduksi ukuran diameter 6 mm menjadi 4 mm, serta panjang awalnya 10 cm menjadi ±26 cm. Dari hasil XRD menunjukkan bahwa sampel dengan doping nikel menghasilkan fasa primer MgB2 dan fasa sekunder MgNi2.5B2 serta beberapa pengotor (MgO dan Mg) dengan ukuran kristalit lebih meningkat dibandingkan MgB2 tanpa doping. Dari gambar SEM, sampel tampak menunjukkan penurunan jumlah porositasnya. Sampel yang disinter 750°C merupakan temperatur optimal dalam mensintesis superkonduktor MgB2 yang didoping nikel karena memiliki Tc onset tertinggi sebesar 42,53 K dan porositas terendah pada pendopingan nikel sebesar 20 persen berat yaitu sebesar 13,5% porositas.

Pengaruh Perlakuan Panas Karburisasi Austempering Pada Baja Laterit Modifikasi Paduan Ni-Cr Terhadap Sifat Mekanik Dan Struktur Mikro Satrio Herbirowo
JURNAL POWERPLANT Vol 7 No 2 (2019): JURNAL POWER PLANT
Publisher : Sekolah Tinggi Teknik - PLN

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33322/powerplant.v7i1.719

Laterite steel is a steel with a low nickel content which is between 1 - 4.5 percent. Generally, the nickel content in laterite steel which was tried to be developed by LIPI ranged from 1.5 to 4.5 percent. The type of laterite steel developed from laterite ore is NPI (Nickel Pig Iron), a type of cast iron that has a high hardness value and optimal toughness. This material is widely used for grinding balls or Hard-Liner materials for crusher or grinder equipment. In the research of the heat treatment process, Carburization of Austempering uses laterite steel with Ni and Ni-Cr alloys. Where this study uses parameters of heating temperature in the Austenisasi temperature of 950 ºC and Austempering temperature of 400 ºC with the same holding time of 1 hour. In this study also used a variation of cooling media (quenching), namely angina fan, water and left in the furnace. Laterite steel which has been processed by carburization Austempering will be tested by testing hardness, impact, metallography. From the test results obtained test data where, the highest value of hardness is found in steel sample 2 (Ni-Cr), which cooling using a fan with a value of 63.6 HRC with the phase produced martensite. And the highest impact value is found in the sample steel 3 (Ni) which cools in the furnace with an impact value of 38J and the phase formed is bainite.

Fabrikasi Kawat Resistansi Nol Berbahan MgB2/Stainless Steel dengan Variasi Reduksi Ukuran melalui Pengerolan Dingin terhadap Karakteristik Mekanik dan Struktur Mikro Satrio Herbirowo; Andika Widya Pramono
Energi & Kelistrikan Vol 13 No 2 (2021): Energi dan Kelistrikan: Jurnal Ilmiah
Publisher : Sekolah Tinggi Teknik PLN

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33322/energi.v13i2.1491

Magnesium Diboride (MgB2) is a high potential material for medical and electrical applications with zero resistance and high efficiency. The raw materials of Mg powder with a purity of 98% and B amorphous with a purity of 95%, were mixed with a ratio of 1:2, ground for 2 hours using an agate mortar, and subsequently compacted and inserted into stainelss steel (SS) tube by powder-in-tube (PIT). The SS tube was previously annealed at 900°C for 1 hour. The sintering process was carried out using a muffle furnace at a temperature of 800°C for 1 hour, followed by cold wire rolling with gradual reduction. The samples were characterized for their mechanical properties using Vickers microhardness tester and ultimate tensile test machine. Surface morphologies of samples were observed using optical microscope and SEM-EDAX Superconducting properties were measured with the cryogenic resistance measurement. The highest hardness value of 377,2 HV was achieved at a 60% size reduction along with the tensile strength of 1381 KN/mm. The results of the morphological observation showed homogeneous deformation without any cracks, with the the grain shape tended to be crystalline. The superconductivity test showed the phenomenon of zero resistance at a critical temperature of 39.55K at a 40% reduction in MgB2 wire

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