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Abstrak--Keadaan yang sedang terjadi pada seksi LPDC di PT. X adalah banyaknya cacat pada produk hasil casting sesuai data cacat pada bulan Januari-Juni 2018 yaitu persentase total cacat tertinggi sebesar 20.64% pada seksi LPDC In Plant dan Next Process di bulan April 2018. Jenis cacat tertinggi pada seksi LPDC In Plant adalah Misrun dinding chain sebesar 3.48% dan pada LPDC Next Process adalah gagal leak test sebesar 4.93%. Hal ini sangat merugikan perusahaan baik dalam biaya produksi yang meningkat dan waktu produksi yang lama. Karakterisasi yang dilakukan pada penelitian ini adalah pengujian leak lest, radiografi (x-ray), optical emission spectroscopy, penetrant, metalografi, SEM, dan uji EDS. Berdasarkan hasil dari karakterisasi yang diperoleh, menunjukkan bahwa produk gagal leak test mengalami cacat internal yaitu shrinkage porosity. Berdasarkan hasil analisis fenomena cacat shrinkage porosity tersebut disebabkan oleh adanya inklusi oksida aluminium yang terbawa ke dalam produk Cylinder Head Type-A yang menjadi inisiasi terbentuknya shrinkage porosity. Terdapatnya oksida aluminium pada produk Cylinder Head Type-A disebabkan oleh waktu transfer molten dari melting furnace yang relatif lama dan jarak auto carrier yang relatif tinggi sehingga turut mempengaruhi waktu pouring ke holding furnace. Kata Kunci: Cylinder Head, Low pressure die casting, leak test, shrinkage porosity, oksida.

Ten stages of Compressor Engine S/N 123 of X-Gas Turbine failed in service prior the schedule for overhaul at 40,000 hour. At the failure event the running hour was 29,600. The maintenance was normally done every 8000 hours including filter and gasket replacement, instrument re-calibration, and bore scope examination. Upon dismantling, it was found one blade at rotor stage #3 failed with facture surface strongly indicated a fatigue failure, defective on stator and rotor blades at downstream, no defective blades at upstream. Detail examination confirm Root Cause of failure on Compressor Blade of X-Gas Turbine were combination of a sharp radius of root chamfer as the major contributor and at lesser extent enhanced by “scratches” exist on root blade free surface. There was no evidences Foreign Objects or corrosion contributed to fail the compressor blades. Blade material was sound and did not contribute to fail the blade. The recommendations to avoid failure reoccurrences were all existing installed rotor blades shall be dismantled and examined for the existence of crack at their root area. Inspection on brand new blades for the existence of scratches on blade surface prior assembly shall be strongly imposed; blade with preexisting scratch shall be rejected. In a design stages, increase the sharp chamfer radius on blade root is worth-while to be analyzed further. Workmanship during blade assembly shall not develop any scratch on blade surface especially on its root surface. A procedure and schedule for inspection on the running blades shall be refined to be able to detect any crack on the operating blades; special attention shall be given on root area.

Hydrogen as an energy source is a promising solution for the future energy problems. From the economic standpoint, the largest obstacle in using the hydrogen is the effective and safe storage equipment. Up to now, there is no hydrogen storage which has a satisfying performance in both capacity and thermodynamics properties. Fe-Ti alloy is promising hydrogen storage because it absorbs hydrogen in room temperature. Unfortunately, its hydrogen absorption capacity is very low (1-1.9 wt %). Aluminum is known as one among the light metals that can be promoted as a substituting agent that can improve the surface area which interact with hydrogen. Alloying aluminum with Fe-Ti alloy is suggested to enhance the hydrogen absorption capacity. The synthesis and characterization of Fe-Ti-Al alloy with the atomic ratio of 10:10:1 prepared by mechanical alloying technique and its hydrogen absorption properties has been performed. The Fe-Ti-Al elemental powders were milled together in toluene solution using a high energy ball milling for 30 hours. The milled specimen is analyzed with an X-Ray Diffractometer and analyzed qualitatively and quantitatively using Rietveld method developed by Fuji Izumi. On hydriding at room temperature using low pressured Sievert Type Apparatus, Fe 10 Ti 10 Al transformed into FeTiH 2 and TiH 2. It is exhibited that Fe 10 Ti 10 Al hydride specimen contains almost 2.5 wt% hydrogen. This is an improvement from Fe-Ti-Mg alloy by Suwarno (2011) which contains 1.75 wt.% hydrogen. Consider the high hydrogen absorption capacity and the low hydriding temperature of this alloy, Fe 10 Ti 10 Al alloy could be promoted as new hydrogen storage materials.