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INDUSTRI LOGAM

INDUSTRI LOGAM. 2010/2011. PENDAHULUAN. Diantara logam - logam , BAJA paling banyak digunakan , mulai dari bangunan hingga otomotif sampai pesawat dan alat transportasi luar angkasa . BAJA adalah kombinasi besi atau alloy dengan logam lain atau non logam , seperti karbon .

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INDUSTRI LOGAM

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  1. INDUSTRI LOGAM 2010/2011

  2. PENDAHULUAN • Diantaralogam-logam, BAJA paling banyakdigunakan, mulaidaribangunanhinggaotomotifsampaipesawatdanalattransportasiluarangkasa. • BAJA adalahkombinasibesiatau alloy denganlogam lain atau non logam, sepertikarbon. • Sifat BAJA lebihlentur (mudahdibentuk), punyadayatahanlebihbaikdaripadabesituang, dan biasanya ditempa, digulung atau ditarik menjadi berbagai bentuk.

  3. SEJARAH

  4. BAHAN BAKU • BIJIH BESI (IRON ORE), consist of hematite (plentiful), limonite (brown iron ore), taconite, dan magnetite (black iron ore). • Coal • Limestone • Need at least 50% of iron ore for efficient operation (in furnace)

  5. PROSES PRODUKSI • Most steel is produced using one of four methods: Bessemer converters, open-hearth furnaces,basic oxygen furnaces, and electric furnaces. • Basic oxygen process is the most efficient, while the Bessemer and open-hearth methods have become obsolete. Electric furnaces are used to produce high quality steels from selected steel scrap, lime, and mill scale .

  6. PROSES BASSEMER • IN : 1860 – 1909 • Bassemer converter adalahbejana yang sangatbesarberbentuksepertibuahpir, dapatmenampung 5 – 25 ton bahanbaku, dengankecepatanalirudara 3000 ft3/menit • Percikandanasaptebalberwarnacoklatkeluardarikonverterketika O2bercampurdenganbesidanmanganuntukmembentuk SLAG.

  7. Setelahitukobaranapisetinggi 9 m, menggantikanasapketika O2bergabungdenganbahanbakardanterbakar. • Proses : 15 menit (whole process) • Kekurangan: penambahanudaramenyebabkanterdapatimpuritas (Nitrogen) sertamenghilangkanelemen yang dibutuhkan (C danMn) • Solusi : menambahkankembalielementsb • Stop Process : PerundanganLingkungan (PolusiUdara) danefisiensiproses

  8. PROSES OPEN-HEARTH FURNACE • IN : 1909 – 1960-an • Limestone dan scrap steel dimasukkankedalam converter dandipanaskanselama 2 jam dengansuhu 1482 – 1649°C sampaikeduanyatercampur. • Kemudiantungkudiisidenganberton-ton besikasarcair, kemudian scrap dipindahkankedalamtungku.

  9. Kemudianditambahkanbeberapaelemenseperti fluxing agent, karbon (biasanyadalambentuk anthracite coal pellet) dancampuranlogamuntukmeningkatkankualitasbaja, menghilangkanefekdarioksidaatauimpuritaslainnya. • Jikapanasdansuhusudahsesuai, maka furnace dimiringkandanlogamcairdituangkecawantuang. • Panas yang dihasilkanuntukmemanaskanbajamembutuhkanwaktu 8 – 12 jam per period

  10. PROSES BASIC OXYGEN FURNACE • MiripdenganBassemerProses • Material dimasukkandariatas furnace kemudianproduk yang dihasilkandituangkankecawantuang. • Elemen yang penting : water cooled-oxygen lance dan fluxing agents • Lance diturunkanuntukmengisikansecaralangsungoksigendengankemurniantinggimenggunakankecepatansupersonikkedalamlogamcair.

  11. Hal tersebutakanmembakarhabisimpuritasdanmemungkinkanmembuatbajadengankandungan nitrogen minimal. • Panas yang digunakanuntukmembentukbajadapatberlangsungselama 30 – 45 menit. • Pengembangan refractory denganmenambahkan insulating ceramics, untukmelindungi vessel dari hot steel

  12. PROSES ELECTRIC FURNACE • Proses yang paling unggul, karenatersedialistrikdenganbiayarendahdanhanya coal atau iron ore yang ditemukan. • Electric furnace prosesinidapatmenghasilkanbaja, campuranbajadankarbonberkualitastinggi. • Prosesberlangsungselama 90 menitdenganmenghasilkan 150 – 200 ton baja. • Furnace inimenggunakanelektrodadenganukuran 0,6 meter (d) dan 7,2 meter (l).

  13. GambarProses

  14. GambarProses

  15. QUALITY CONTROL • Melaksanakanserangkaian test, untukmengetahuisifatfisikmaupunmekanikdariproduk. • Test seperti Metallurgical, hardness (kekerasan), hardenability (sifatdapatkuat), tension (tekanan/tarikan), ductility (sifatdapatdiregang), compression (pemadatan), fatigue (kelelahanbahan), impact (tumbukan), wear (pengausan/aus), corrosion (korosi), creep (sifatdapatmulur), machinability, radiography, magnetic particle, ultrasonic, and eddy current (aruskisar)

  16. Metallurgical testing is used to determine the quality of steel by analyzing the microstructure of a sample under a microscope. • It is possible to determine grain size and the size, shape, and distribution of various phases and inclusions (nonmetallic material) which have a great effect on the mechanical properties of the metal. • Hardness is not a fundamental property of a material, but is related to its elastic and plastic properties.

  17. Hardenability is a property that determines the depth and distribution of hardness induced by quenching. • The tensile test is used to determine several important material properties such as yield strength, where the material starts to exhibit plastic or permanent deformation, and the ultimate tensile or breaking strength. • Ductility of a material is indicated by the amount of deformation that is possible until fracture and can be determined by measuring elongation and reduction in area of a tensile sample that has been tested to failure.

  18. The fatigue test is used to determine the behavior of materials when subjected to repeated or fluctuating loads. • The fatigue potential, or endurance limit, is determined by counting the number of cycles of stress. • Fatigue tests can be used to study the material behavior under various types and ranges of fluctuating loads and also the effect of corrosion, surface conditions, temperature, size, and stress concentrations.

  19. Impact tests are used to determine the behavior of materials when subjected to high rates of loading, usually in bending, tension, or torsion. • Corrosion involves the destruction of a material by chemical, electrochemical, or metallurgical interaction between the environment and the material • Machinability is the ease with which a metal may be machined. • Machinability ratings are expressed as a percentage, in comparison with AISI 1112 steel, which is rated at 100%. Metals which are more difficult to machine have a rating of less than 100% while metals which machine easily have a rating more than 100%.

  20. Radiography of metals involves the use of x-ray or gamma rays. The short-wavelength electromagnetic rays are capable of going through large thickness of metal and are typically used to nondestructively test castings and welded joints for shrinkage voids and porosity. • Magnetic particle inspection is a method of detecting cracks, tears, seams, inclusions, and similar discontinuities in iron and steel. This method will detect surface defects too fine to be seen by the naked eye and will also detect discontinuities just below the surface.

  21. Ultrasonic inspection is used to detect and locate such defects as shrinkage voids, internal cracks, porosity, and large nonmetallic inclusions. • Eddy current inspection is used to inspect electrically conducting materials for defects and variations in composition. Eddy current testing involves placing a varying magnetic field. • . Properties such as hardness, alloy composition, chemical purity, and heat treat condition influence the magnetic field and may be measured through the use of eddy current testing.

  22. THANK YOU…

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