M. Dani
Center for Nuclear Industry Material Technology - BATAN Puspiptek, Serpong, Tangerang 15314, Indonesia

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Rolling and Annealing Effects on Microstructure and Hardness of Commercial 405 Stainless Steel Jahja, A.K.; Effendi, N.; Dani, M.
Atom Indonesia Vol 33, No 2 (2007): July 2007
Publisher : PPIKSN-BATAN

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (8007.934 KB) | DOI: 10.17146/aij.2007.109

Abstract

The "cold-rolling" experiments for several values of true strain namely 5 percent, 10 percent, and 15 percent respectively have been carried out on commercial SS-405 steel samples at 350oC; the as-rolled samples were cut into several pieces in size of 10 x 10 x 5 mm3, and some pieces were annealed to 550oC for 24 hours. All samples were then mounted and polished before etching in order to observe the grain boundaries. The microstructure observation on all samples was carried out by using optical microscope (MO), meanwhile X-ray diffraction technique was employed in order to support the identification of the existing phases and to verify changes with respect to crystal orientation; the hardness tests were carried out by using Vickers micro hardness tester. The microstructure observation supported by X-ray diffraction results shows that the phase grains of rolled sample tends to take the oblong-shape, accompanied by a preferred orientation predominantly inclined toward the (110) plane. The microhardness testing results show that there has been an increase in the hardness of the as-rolled samples; Mainly because of the nearly negligible thickness of the original sample (being only 5 mm in size), the 15 percent as-rolled samples exhibits only a slight reduction in hardness compared to the 10 percent as-rolled samples; The main cause of this effect is the movement of some dislocations infiltrating the surface resulting in the reduction of the inner-stress in the bulk of the samples. In the rolled-annealed samples there is a very significant reduction in hardness compared to the as-rolled samples. Here the main cause is the recrystallization process taking place during annealing, which tends to significantly reduce the dislocations.
KETAHANAN OKSIDASI BAJA SUPER AUSTENITIK 15%CR-25%NI PADA TEMPERATUR 850 °C Parikin, Parikin; Sugeng, B.; Dani, M.; Sukaryo, S.G.
Jurnal Sains Materi Indonesia Vol 18, No 4: Juli 2017
Publisher : BATAN

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (408.131 KB) | DOI: 10.17146/jsmi.2017.18.4.4128

Abstract

ABSTRAKKetahanan Korosi Temperatur Tinggi Baja Super Austenitik 15%Cr-25%Ni Pada Temperatur 850 °C. Ketahanan korosi temperatur tinggi atau ketahanan oksidasi merupakan prasyarat penting bahan logam yang akan diterapkan dilingkungan operasi bertemperatur tinggi.  Pengujian ketahanan oksidasi baja super austenitik 15%Cr-25%Ni pada temperatur 850 °C selama 5 jam lebih telah dilaksanakan. Satu sampel as-cast sebagai acuan awal yang tidak diperlakukan panas dan dua (2) kelompok sampel (masing-masing 3 buah) disiapkan dalam eksperimen. Satu kelompok sampel as-cast setelah dipanaskan (pada 850 °C /5 jam lebih) dan didinginkan perlahan kemudian ditimbang. Satu kelompok sampel quench yang dilakukan penurunan cepat temperatur (dari 850 °C / 5 jam lebih) ke dalam air, kemudian ditimbang. Percobaan dilakukan selama 15 jam lebih pada masing-masing kelompok. Hasil memperlihatkan bahwa walaupun terjadi kenaikan berat sangat kecil pada sampel as-cast dan quench, tetapi foto morfologi mikroskop elektron (SEM) pada kedua sampel tersebut tidak memperlihatkan perubahan yang signifikan. Demikian pula hasil analisis fasa menggunakan difraksi sinar-X, tidak memperlihatkan pertumbuhan fasa produk oksidasi. Hasil  pengamatan struktur mikro permukaan bahan menggunakan mikroskop optik (MO), juga tidak memperlihatkan kerusakan dan perubahan ukuran butir oleh proses oksidasi. Kebolehjadian pada fenomena ini adalah selain pembentukan spinel unsur Ni diperkuat juga oleh kemampuan unsur Cr untuk membentuk lapisan pasif (Cr2O3) dipermukaan bahan yang sangat besar dengan mengikat unsur O, sehingga bahan mampu menanggulangi produk oksidasi yang sangat kecil. Disimpulkan bahwa baja super austenitik memiliki ketahanan oksidasi yang baik pada temperatur 850°C.ABSTRACT High Temperature Corrosion Resistance of Super Austenite 15%Cr-25%Ni Steel at Temperature 850 °C. High temperature corrosion resistance so called oxidation resistance is an important prerequisite of a metal material that may be applied in a high-temperature operating environment. An oxidation test of super austenite steel 15% Cr-25% Ni at 850 °C for more than 5 hours has been performed. One as-cast specimen as an initial reference is not treated any heat and two (2) specimen groups (each of 4 pieces) were prepared in the experiments. One group of as-cast specimens after being heated at 850 °C for more than 5 hours and cooled slowly then weighed. Another group of quench specimens performed a rapid decrease of temperature (850 °C for more than 5 hours) into water, then weighed. The experiment was conducted for more than 15 hours in each group. The results show that there is a very small slight increase in weight on as-cast and quench specimens. However, electron microscope morphology (SEM) images on both specimens showed no significant changes. Similarly, the results of phase analysis using X-ray diffraction techniques also do not show the phase growth of oxidation products. In accordance with the observation of surface microstructures of materials by using optical microscope (OM), also did not show damage and changes in grain size by oxidation process. The likelihood of this phenomenon is that in addition to the formation of Ni element of spinels, it is also strengthened by the ability of Cr-elements to form a passive layer (Cr2O3) on a very large material surface by binding O-elements, so that the material can cope with very small oxidation products. It is concluded that the super austenitic steels has good oxidation resistance at 850°C.
EFEK ROL PANAS PADA SIFAT MEKANIK PLAT BAJA 15%Cr-25%Ni BAHAN STRUKTUR REAKTOR Parikin, Parikin; Priyanto, Tri Hardi; Ismoyo, Hadi; Dani, M.
Jurnal Sains Materi Indonesia Vol 17, No 1: OKTOBER 2015
Publisher : BATAN

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (407.703 KB) | DOI: 10.17146/jsmi.2015.17.1.4198

Abstract

ANALISIS STRUKTURMIKRO, POROSITAS DAN KEKERASAN DARI PADUAN AlSi HASIL COR PERAH S., Sulistioso G.; Dani, M.; Wagiyo, Wagiyo; P., Elman; Sunardi, Sunardi; Firdaus, Firdaus
Jurnal Sains Materi Indonesia VOL 4, NO 1: OKTOBER 2002
Publisher : Center for Science & Technology of Advanced Material - National Nuclear Energy Agency of

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (769.465 KB) | DOI: 10.17146/jusami.2002.4.1.4890

Abstract

ANALISIS STRUKTURMIKRO, POROSITAS DAN KEKERASAN DARI PADUAN AlSi HASIL COR PERAH. Telah dilakukan penelitian dan analisis sifat fisis dan mekanik dari paduanAlSi yang dibuat dengan metoda cor perah. Kegagalan dari produk yang sekarang digunakan yang dibuat dengan cetakan pasir, adalah keausan (wear) yang terjadi di bagian lubang tempat penyangga poros baling-baling, di ujung dari flens. Untuk mendapatkan karakteristik yang sesuai dengan bentuk aslinya, maka dibuat spesimen yang bentuknya menyerupai ujung dari flens tersebut dengan cara cor perah. Spesimen dibuat dengan parameter sebagai berikut suhu die 450oC, 500oC, 550oC, dengan tekanan 70 MPa, 100 MPa dan 130 MPa untuk masing-masing suhu die. Karakterisasi yang dilakukan meliputi uji komposisi, uji keras , analisis strukturmikro dan densitas. Kekerasan sampel uji yang merupakan produk cetakan pasir (CP) = 76,51 Kg/mm2, dan kekerasan spesimen produk cor cara perah (SQ) = 88,270. Porositas CP = 6,53 %, porositas SQ = 0,79%. Dari hasil foto strukturmikro didapat bahwa sampel produk cor perah mempunyai denrit yang lebih halus. Kesimpulan dari penelitian ini adalah cara cor perah dapat menaikkan kekerasan, menurunkan porositas, dan memperbaiki strukturmikro.