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Abstrak :
ABSTRAK
Baja ODS (Oxide Dispersion Strengthened) merupakan paduan dengan ketahanan temperatur dan korosi yang baik. Penggunaan metode iradiasi ultrasonik di dalam larutan toluene merupakan metode baru yang dapat memberikan keuntungan berupa ukuran butir yang halus, dapat membentuk microalloying di dalam serbuk, dan dapat meminimalisasi pembentukan fasa oksida. Penelitian ini mempelajari tentang pengaruh amplitudo terhadap reduksi ukuran partikel, homogenitas serbuk, dan pembentukan microalloying Fe-Cr pada preparasi serbuk Fe-15Cr-0.5Y2O3. Serbuk dibagi menjadi 4 sampel dengan perlakuan pencampuran mortar (sampel A), iradiasi ultrasonik dengan amplitudo 40% (sampel B), 50% (sampel C), dan 60% (sampel D) yang kemudian dikarakterisasi menggunakan SEM, EDS, dan XRD. Hasil dari penelitian ini adalah peningkatan amplitudo akan menurunkan ukuran butir dengan nilai sampel B>sampel C>sampel D adalah 4.63 μm>3.44 μm>3.09 μm. Sampel C menghasilkan partikel Fe-Cr sementara sampel B dan D terbentuk partikel paduan Fe-Cr-Y2O3. Nilai komposisi Fe-Cr terbesar dicapai pada amplitudo 40% dengan nilai sampel A:sampel B:sampel C: sampel D adalah 0.00%:20.5%:10.06%:5.2% tanpa pembentukan oksida dengan ukuran crystallite Fe-Cr sampel B:sampel C:sampel D berukuran 16.79 nm:30.13 nm: 55.69 nm. Nilai lattice strain sampel B:sampel C: sampel D adalah 0.0055:0.0030:0.0016.

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ABSTRACT
ODS Steel (Oxide Dispersion Strengthened) is an alloy with good corrosion and high temperature resistance. The utilization of ultrasonic irradiation method in toluene solution is a new method giving benefits like producing fine grain-size, forming micro-alloying on powder, and minimizing the oxide phase formation. This research investigates the influence of amplitude on the reduction of the particle size, the homogeneity of the powder, and the formation of Fe-Cr microalloying on Fe-15Cr-0.5Y2O3 powder preparation. The powder was divided into 4 samples with various treatments such as mortar mixing (sample A) and ultrasonic irradiation with an amplitude of 40% (sample B), 50% (sample C) and 60% (sample D). After that, each sample was characterized by SEM, EDS and XRD. This research shows that increasing the amplitude will decrease the grain size with the value of sample B> sample C> sample D is 4.63 μm>μm 3:44> 3:09 μm. Sample C produced Fe-Cr particles meanwhile samples B and D formed Fe-Cr-Y2O3 alloy particle. The highest composition value of Fe-Cr is reached on the amplitude of 40% to the composition value of sample A: sample B: sample C: sample D is 0.00%: 20.5%: 10:06%: 5.2% without the oxide formation. The size of crystalline Fe-Cr sample B: sample C : sample D size of 16.79 nm: 30.13 nm: 55.69 nm. The lattice strain value of the sample B: the sample C: sample D was 0.0055: 0.0030: 0.0016. ;

Abstrak :
We conducted a finite element simulation by using a computer program, ATENA, to verify the behavior of T-section reinforced concrete beams strengthened by bonded wire ropes in the negative moment region with a pretensioned initial prestressing force; we compared this behavior with that in experimental tests. The simulation was performed on five models consisting of one unstrengthened beam and beams strengthened by wire ropes with initial prestressing forces of 0%, 10%, 20%, and 30%. We found that the capacity of a flexural load had the ratios to the experimental results close to 1 ? that is, 1.25, 1.16, 1.12, 1.01, and 1.10, for UB, SB1, SB2, SB3, and SB4, respectively. The ratios of effective stiffness, as the result of the simulation, to the experimental results were 1.45, 1.08, 1.76, 2.13, and 2.46 for UB, SB1, SB2, SB3, and SB4, respectively. We also observed that crack propagation developed in the finite element simulation indicated that all models underwent flexural failure.

Abstrak :
ABSTRACT
Kekayaan mineral Indonesia yang merupakan berkah dari posisi strategis Indonesia yang secara geologis berada di jalur Ring of Fire dan jalur timah dunia belum dioptimalkan bagi kepentingan nasional. Dengan kemajuan teknologi mineral (teknologi maju atau advanced technology) telah terbukti bahwa mineral strategis untuk industri pembuat Alutsista atau sering dikenal sebagai Oxide Dispersion Strengthened/ODS Metal Alloys semakin penting dan sudah menjadi sebuah komoditas yang menarik dan diperebutkan bagi industri maju. Fakta bahwa mineral ODS tersebut belum dioptimalkan tampak dari belum ketatnya pengawasan terhadap perusahaan atau korporasi tambang dalam memenuhi kewajibannya untuk membangun pabrikpemurnian (smelter) dan memastikan untuk mengolah lebih lanjut hasil pemurnian mineral tersebut yang notabene berupa mineral ikutan yang strategis ( ODS) di dalam negeri sebagaimana diamanatkan oleh U U Minerba. Hambatan-hambatan yang ada seperti lemahnya sinergitas kelembagaan, regulasi yang kontraproduktif dan terbatasnya infrastruktur bagi terwujudnya pengelolaan, pengolahan dan penguasaan mineral strategis ( ODS) bagi kepentingan nasional terutama industri pertahanan harus diminimalkan dengan intervensi negara untuk menata ulang master plan industri nasional yang dipadukan dengan roadmap industri pertahanan yang sudah ada serta merumuskan master plan industri pertahanan berbasis pemanfaatan ODS dengan percepatan penguasaan teknologi maju di bidang mineral.

Abstrak :
We conducted a finite element simulation by using a computer program, ATENA, to verify the behavior of T-section reinforced concrete beams strengthened by bonded wire ropes in the negative moment region with a pretensioned initial prestressing force; we compared this behavior with that in experimental tests. The simulation was performed on five models consisting of one unstrengthened beam and beams strengthened by wire ropes with initial prestressing forces of 0%, 10%, 20%, and 30%. We found that the capacity of a flexural load had the ratios to the experimental results close to 1 — that is, 1.25, 1.16, 1.12, 1.01, and 1.10, for UB, SB1, SB2, SB3, and SB4, respectively. The ratios of effective stiffness, as the result of the simulation, to the experimental results were 1.45, 1.08, 1.76, 2.13, and 2.46 for UB, SB1, SB2, SB3, and SB4, respectively. We also observed that crack propagation developed in the finite element simulation indicated that all models underwent flexural failure.