Materials Selection
Steel – what, where, when, why? What is steel made of? How many tons produced per year world-wide? How many tons produced per year US? How many tons used per year US? Major uses / products? Kinds of steel?
Steel – what, where, when, why? What is steel made of? Fe + C + (Mo, Mn, Cr, Ni, Si, etc.) How many tons produced per year world-wide? 100,000,000 How many tons produced per year US? 13,000,000 How many tons used per year US? 31,000,000 Major uses / products? automotive, construction, oil & gas, appliances, containers, Kinds of steel? low C, high C, alloy, stainless, martensitic, etc.
Steel products and prices: AVERAGE IMPORT CUSTOMS VALUE PER NET TON* Product August 2003 21 Year Ave % Change Wire Rods $302 $349 -13.60% Bars - Hot Rolled $429 $455 -5.90% Bars - Cold Finished $903 $927 -2.60% Standard Pipe $462 $468 -1.10% Oil Country Goods $598 $685 -12.70% Mechanical Tubing $677 $775 -12.60% Structural Pipe & Tubing $446 $452 -1.30% Wire-Drawn and/or Rolled $767 $811 -5.40% Tin Plate $557 $574 -3.00% Sheet & Strip Galv. (Electrolytic) $479 $555 -13.80% Electrical Sheet & Strip $715 $923 -22.50% Strip - Hot Rolled $379 $445 14.90% Note: record import surge began in the first quarter of 1998. * Includes Carbon, Alloy and Stainless Source: U. S. Dept. of Commerce, Bureau of the Census
% change 2002 Annualized vs 94-97 Avg.* Imported from where? U.S. IMPORTS OF FINISHED STEEL MILL PRODUCTS BY COUNTRY OF ORIGIN (thousands of net tons) Prelim 8 Mos 2003 8 Mos 2002 2003 Annualized Prelim Annual Average 1994-1997* % change 2002 Annualized vs 94-97 Avg.* Canada 3,315 3,847 4,973 - European Union 2,256 2,954 3,384 6,111 -44.60% Mexico 988 1,136 1,482 Korea 812 1,148 1,218 1,432 -14.90% Turkey 685 694 1,028 460 123.50% Japan 650 1,184 975 2,200 -55.70% China 435 313 653 362 80.40% Brazil 350 344 525 850 -38.20% India 318 299 477 138 245.70% Australia 254 217 381 56 580.40% Argentina 189 150 154.00% Egypt 247 204 371 51 627.50% South Africa 218 180 327 321 1.90% Romania 190 140 285 92 209.80% Others 1,411 1,993 2,117 4,375 -51.60% Total 12,383 14,842 18,575 22,192 -16.30%
C content in steels : Type of steel: Fe + ... Typical uses: Low-C .04-.3% C general construction, low applications. Medium-C .3-.7% C machinery parts, nuts, bolts, shafts, gears, medium High-C .7-1.7% C springs, cutting tools, dies, high uses. Cast Iron 1.8 - 4% C engine blocks, drain pipes, machine cabinets
Phase diagrams : T L A B b +b +L b+L
Iron - carbon phase diagram Fe-Fe3C Phase Diagram, Materials Science and Metallurgy, 4th ed., Pollack, Prentice-Hall, 1988 http://www.sv.vt.edu/classes/MSE2094_NoteBook/96ClassProj/examples/kimcon.html
Iron - carbon phases
Iron - carbon transformations http://www-g.eng.cam.ac.uk/mmg/teaching/typd/addenda/microstructures1.html
Pure Fe phase changes :
Eutectoid reaction :
Lever rule : % is d c + d % is c x c d T A x1 x x2 B
Hypoeuctictoid steels :
Hypereutectoid Steel :
Transformations : Equilibrium transformations (slow cooling) -> “ferrite” -> Fe3C “iron carbide” -> + Fe3C “pearlite” Nonequlibrium (fast cooling / quenching) -> ’ “martensite”
Pearlite : Two phases ( + Fe3C)
Martensite : Quenched in distortions : + C C Fe
Martensite mechanical prop. : very hard and very brittle (too brittle !!!)