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Baja Karbon(Steel). Pertanyaan ttg Baja –> what, where, when, why? Apa itu baja? Berapa ton/tahun baja dibuat di dunia? Berapa ton/tahun di Amerika? Berapa.

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Presentation on theme: "Baja Karbon(Steel). Pertanyaan ttg Baja –> what, where, when, why? Apa itu baja? Berapa ton/tahun baja dibuat di dunia? Berapa ton/tahun di Amerika? Berapa."— Presentation transcript:

1 Baja Karbon(Steel)

2 Pertanyaan ttg Baja –> what, where, when, why? Apa itu baja? Berapa ton/tahun baja dibuat di dunia? Berapa ton/tahun di Amerika? Berapa ton/tahun digunakan/konsumsi di Amerika? Pengguna utama siapa? Jenis Baja?

3 Steel – what, where, when, why? Apa itu baja? Fe + C + (Mo, Mn, Cr, Ni, Si, etc.) Berapa ton/tahun baja dibuat di dunia ? 100,000,000 Berapa ton/tahun di Amerika ? 13,000,000 Berapa ton/tahun digunakan/konsumsi di Amerika ? 31,000,000 Pengguna utama siapa ? automotive, construction, oil & gas, appliances, containers, Jenis Baja ? low C, high C, alloy, stainless, martensitic, etc.

4 Produk2 baja dan harga: AVERAGE IMPORT CUSTOMS VALUE PER NET TON* ProductAug ust Ye ar Av e % Ch an ge Wire Rods$302$ % Bars - Hot Rolled$429$ % Bars - Cold Finished$903$ % Standard Pipe$462$ % Oil Country Goods$598$ % Mechanical Tubing$677$ % Structural Pipe & Tubing$446$ % Wire-Drawn and/or Rolled$767$ % Tin Plate$557$ % Sheet & Strip Galv. (Electrolytic)$479$ % Electrical Sheet & Strip$715$ % Strip - Hot Rolled$379$ % Note: record import surge began in the first quarter of * Includes Carbon, Alloy and Stainless Source: U. S. Dept. of Commerce, Bureau of the Census

5 Negara importir baja ke US? U.S. IMPORTS OF FINISHED STEEL MILL PRODUCTS BY COUNTRY OF ORIGIN (thousands of net tons) Prelim 8 Mos Mos Annualized Prelim Annual Average * % change 2002 Annualized vs Avg.* Canada3,3153,8474,973-- European Union2,2562,9543,3846, % Mexico9881,1361,482-- Korea8121,1481,2181, % Turkey , % Japan6501, , % China % Brazil % India % Australia % Argentina % Egypt % South Africa % Romania % Others1,4111,9932,1174, % Total12,38314,84218,57522, %

6 Kandungan karbon C pada baja : Type baja:Fe +...Aplikasi: Low-C.04-.3% CKontruksi umum, low  applications. Medium-C.3-.7% Cmachinery parts, nuts, bolts, shafts, gears, medium  High-C.7-1.7% Csprings, cutting tools, dies, high  uses. Cast Iron % Cengine blocks, drain pipes, machine cabinets

7 Diagram Fasa : T  L A B    L  L

8 Diagram besi-karbon Fe-Fe3C Phase Diagram, Materials Science and Metallurgy, 4th ed., Pollack, Prentice- Hall, 1988

9 Iron - carbon phases

10 Iron - carbon transformations

11 Fe murni berubah fasa :

12 Reaksi Eutectoid :

13 Lever rule : T   A B x 1 x x 2 c d %  is d c + d %  is c c + d x

14 Baja Hypoeuctictoid :

15 Baja Hypereutectoid :

16 Transformations : Equilibrium transformations (slow cooling)  ->  “ferrite”  -> Fe 3 C“iron carbide”   ->  + Fe 3 C “pearlite” Nonequlibrium (fast cooling / quenching)  ->  ’“martensite ”

17 Pearlite : Two phases (  + Fe 3 C)

18 Martensite : Quenched in distortions : Fe C + C

19 Martensite mechanical prop. : Keras/very hard dan Getas/very brittle (too brittle !!!)

20 Transformations : Equilibrium transformations (slow cooling)  ->  “ferrite”  -> Fe 3 C“iron carbide”   ->  + Fe 3 C “pearlite” Nonequlibrium (fast cooling / quenching)  ->  ’“martensite ”

21 Pearlite : Two phases (  + Fe 3 C)

22 Normalized (slow cooled) steels; mechanical properties : Strength (MPa) w/o Carbon 01% 2, UTS YS Ductility (%) 0 50 ff

23 Martensite : Quenched in distortions : Fe C + C

24 Quench and Temper : Temper : heat treat at intermediate T ( C) Mechanical properties: Toughness meningkat (critical) namun kekerasan sedikit turun Strukturmikro : C membentuk presipitates Fe 3 C, dan penurunan distorsi dengan turunnya kandungan C yang terlarut. Hilangnya distorsi membentuk struktur bcc yang ductility. Fe 3 C precipitates - precipitation strengthen the .

25 Quenched and tempered : Strength (MPa) w/o Carbon 01% 2, UTS YS Ductility (%) 0 50 ff UTS YS ff normalized tempered

26 Heat treatments and cooling : Normalizing (heating to form  ) T ~ 1,000 C much easier to roll / forge / form at this temperature Quench- or -Slow cooling martensite pearlite Tempering (heating to “soften” martensite) carbides form, distortions relax

27 Quench rates : To form martensite in pure Fe Critical Cooling Rate (CCR) ~ 100,000 C/sec To form martensite in mild steel : Fe - 0.8% C CCR ~ 200 C/sec To form martensite in alloy steels : Fe %C + 2-7% (Mo, Mn, Cr, Ni) CCR < 1 C/sec

28 Alloying elements are added to : improve hardenability of the steel aides nucleation of martensite solution strengthen and precipitation hardening M x C y carbides form give corrosion resistance especially Cr which forms Cr stabilize FCC austenite at RT especially Ni tougher, more ductile and easier to form non-magnetic and creep resistant (diffusion is slower in FCC)

29 Alloying of steels : Type of steel:Fe +...Typical uses: Low-alloy.2%C +pressure vessels, aircraft.8Mn,1Cr,2Ni parts, high  applications. High-alloy.1% CHigh T and anti-corrosion, Stainless-steels.5Mn,18Cr,8Ni silverware, medical, etc.

30 Steel terminology (SAE-AISI) : Plain carbon 10xx Manganese steels 13xx Nickel steels 23xx Ni-Cr-Mo steels 43xx HSLA 9xx Note: xx indicates carbon content in hundredths of a percent

31 Other steel standards : SAE-AISI Society of Automotive Engineers ; American Iron and Steel Institute ASTM American Standards for Testing and Materials AMS Aerospace Materials Specifications DIN Deutsches Institut fur Normung JIS Japanese Industrial Standards Committee UNS Unified Numbering System


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