Steel Flashcards
<p>Types of steel</p>
<p>steel advantages = high strength + ductility, ease/speed/precision</p>
<p>disadvantages = melts when heated, will corrode</p>
<p>low carbon steel = .06-.3%</p>
<p>medium carbon = .3-.5%</p>
<p>high carbon = .5-.8%</p>
<p>as carbon increases, strength increases, but ductility decreases, so medium is 'best'</p>
<p>weathering steel = corten/has copper added to form patina</p>
<p>A36/A992 = common in W shapes (.25-.29 carbon)</p>
<p>A440 = high strength, for bolting, riveting</p>
<p>A441 = low alloy for welding</p>
<p>Ornamental metals</p>
<p>handrails, guardrails, elevator interiors, metal panels, door/partition facings, signs, light fixtures, ceilings, meshes and perforations,Âetc.Â</p>
<p>most common: SS, Cu alloys, bronze, brass, Al</p>
<p>less common: carbon steel, Cu, iron, porcelain enamel</p>
<p>10 gauge min. in lg. sheets to avoid oil canning, unless back laminated, or embossed</p>
<p>Metal fabrications</p>
<p>non-structural, like stairs, expansion jts. (both structural and seismic), gratings, ladders, etc.Â</p>
<p>Types of stainless steel</p>
<p>302: Cr, Ni added, very strong, hard corrosion resistant</p>
<p>304: like 302, but more weldable, commonly used</p>
<p>301: less Cr, Ni, better tensile strength</p>
<p>316: for extremely corrosive environments</p>
<p>430: no Ni, less corrosion resistance, interiors only</p>
<p>W_x_</p>
<p>nominal depth x weight lbm/ft</p>
<p>Cast iron first reasonable</p>
<p>1709, Abraham Darby used coke not charcoal in production, decreased impurities, increased strength</p>
<p>Steel first reasonable</p>
<p>1856 Henry Bessamer process makes steel inexpensive, stronger</p>
<p>Types of Steel Shapes</p>
<p>wide flanges (W), I-beams (S), channels (C), structural tees (WT or ST), angles (L), tubes (TS) - round/square/rectangle, plates (PL) (more than 6"), bars (less than 6")</p>
<p>Non-ferrous metals</p>
<p>Al: soft, so alloyed w Mn, Zn, Mg, Cu, usu. extruded, high stength to wt., but high embd. energy</p>
<p>Cu: very non-corrosive bc of patina (oil or wax can slow this process), v. conductive, used for wiring, pipes, ornament</p>
<p>Bronze: Cu + Sn</p>
<p>Brass: Cu + Zn</p>
<p>Zn: non corrosive, for roofing/flashing</p>
<p>Pb: good acoustics, easy to form, non-corrosive, poisonous</p>
<p>Types of metal decking</p>
<p>Most often steel, sometimes aluminum; composites ats structurally with concrete infill; cellular allows raceways</p>
<p>Metal finishing</p>
<p>bending, brake forming, spinning, embossing</p>
<p>annealing = reheated + slowly cooled to make more ductile</p>
<p>quenching = reheated + cooled quickly in water to strengthen</p>
<p>tempering = reheated + medium coolest to strengthen + increase ductility</p>
<p>case hardening = harder surface, softer core</p>
<p>anodizing = electrolytic bath that does surface chemistry to help corrosion resistance</p>
<p>painting/coating = for protection or aesthetics</p>
<p>Steel channels used for:</p>
<p>framing openings, stringers, where flush side is needed - buckle easily bc of asymmetry</p>
<p>Light gauge metal framing</p>
<p>10-25 gauge; usu galv. steel, sometimes aluminum; used for interior partions, exterior walls (bearing or non), joist, rafters, etc.; NONCOMBUSTIBLE; doesn't shrink with ageÂ</p>
<p>Cast iron common</p>
<p>1876, used in roofs in France</p>
<p>1850-1880 = Cast Iron Age</p>
<p>Levels of metal finish</p>
<p>No. 3 = dull, coarse</p>
<p>No. 4 = general purpose, still dull/coarse, common</p>
<p>No. 6 = sull satin</p>
<p>No. 7 = reflective</p>
<p>No. 8 = mirror-like</p>
<p>Cast iron showcased</p>
<p>1851; Crystal Palace, Joseph Paxton</p>
<p>1889; Eiffel Tower, Halle des Machines</p>
<p>Open-web steel joists</p>
<p>bottom chord & webs = bent rods</p>
<p>top chord = angles w/ bearing plate attached</p>
<p>Types of open-web steel joists</p>
<p>K-series (2" increments) (spans 8-60 ft), LH-series (4" incr.) (spans 25-96 ft), DLH-series (4") (spans 89-144 ft), e.g. 36LH13 (36" depth, LH-series, type 13 chord). Chord number increases as strength increases.</p>
<p>Metal fabrication types</p>
<p>casting (molds), hot rollingÂ(W-shapes, finer, less strong, more flexible), cold rolling (stronger, more brittle), extruding, drawing (stronger)</p>
<p>Galvanic Action Index</p>
<p>Most reactive metals: Mg, Zn, Al, Mild Steel, Cast Iron</p>
<p>Medium: Cu, Ni, Cr, Pb, Sn, Stainless Steel (active)</p>
<p>Least reactive: Brass, Bronze, Stainless Steel (passive)</p>
<p>Types of iron</p>
<p>wrought = low carbon, has slag, soft/ductile, corrosion resistant</p>
<p>cast = ~2% carbon, hard & brittle</p>
<p>grey cast iron = high silicon content, for plumbing uses</p>
<p>Cast iron + Steel = 1st skyscraper</p>
<p>1885, cast iron int/ext cols., Bessamer girders, William LeBaron Jenny, 10-story, Home Insurance Bldg., Chicago</p>
<p>Cast iron first used in buildings</p>
<p>By 1779, common in bridges and columns</p>
<p>Metal joining</p>
<p>bolts, screws, welding (>800 deg F), brazing (800-500 deg F - only filler melts), soldering (used for lower melting pt. metals, only filler melts)</p>
Why gauge doesn't matter
proprietary, different ones, too confusing, go with actual dimensions, not nominal
Metal processing
smelting = refining
alloying = adding different metals to main metal to confer good properties
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