Transcript Slide 1
Engineering Drawing and Design Seventh Edition Chapter 12 Cast Irons & Ferrous Metals • Ferrous Metals: Iron and the large family of iron alloys called STEEL are the most frequently specified metals. • Cast Iron: Low cost but its properties can vary greatly depending on how it is manufactured (rate of cooling, thickness of casting, how long it remains in mold) – Ductile (nodular) iron is used when higher ductility or strength is required than is available in gray iron. (crank shafts, heavy-duty gears, automobile door hinges) – Grey iron is a supersaturated solution of carbon in an iron matrix and is widely available. (automotive blocks, flywheels, brake disks & drums, machine bases, gears) – White iron is produced by chilling which prevents the graphite carbon from precipitating out. Wear resistant(mill liners, shot-blasting nozzles) Cast iron continued • High-Alloy irons: ductile, gray or white iron that contain over 3%alloy content • Malleable iron (ferric and pearlitic) is produced by a 2-stage heating process and is strong and ductile, has good impact and fatigue properties, and excellent machining characteristics Carbon Steel is an iron-carbon alloy with small amount of other elements • Cast or wrought into different mill forms • Wrought steel is either poured into ingots or sand-cast • Carbon and low-alloy cast steels lend themselves to the formation of streamlined, intricate parts with high strength & rigidity • High-alloy cast steel (minimum 8% nickel and/or chromium) Carbon steels account for over 90% of total steel production • The conditions under which the steel solidifies have a significant effect on its properties • Steel specification: chemical or mechanical properties, by its ability to meet a standard specification, or by its ability to be fabricated into an identified part. Chemical Composition of steel • Carbon: the principal hardening element in steel (.85% gives greater hardness, less ductility) • Manganese: increasing manganese increases the rate of carbon penetrations during carburizing but decreases weldability • Phosphorus • Silicon • Sulfur • Copper • Lead MANUFACTURING MATERIAL SCHEMATIC DIAGRAM OF A BLAST FURNACE MANUFACTURING MATERIAL FLOWCHART FOR STEELMAKING MANUFACTURING MATERIAL FLOWCHART FOR STEELMAKING Classification Bodies • SAE: Society of Automotive Engineers • AISI: American Iron and Steel Institute • ASTM: American Society for Testing & Materials • ASME: American Society of Mechanical Engineers SAE and AISI System of steel identification • • • • Four numbered code First number: major class of steel Second number: subdivision of major class Third & Fourth numbers: Carbon content (hundredths of one percent) • Example: SAE 2335 is a nickel steel containing 3.5 % nickel and .35 of 1% carbon MANUFACTURING MATERIAL CARBON STEEL DESIGNATIONS TYPE OF CARBON STEEL NUMBER SYMBOL PRINCIPAL PROPERTIES COMMON USES Plain carbon 10XX Low-carbon steel (0.06 to 0.20% carbon) 1006 to 1020 Toughness and less strength Chains, rivets, shafts, and pressed steel products Medium-carbon steel (0.20 to 0.50% carbon) 1020 to 1050 Toughness and strength Gears, axles, machine parts forgings, bolts and nuts High-carbon steel 1050 and over Less toughness and greater hardness Saws, drills, knives, razors, finishing tools and music wire Sulfurized (free-cutting) 11XX Improves machinability Threads, splines, and machined parts Phosphorized 12XX Manganese steels 13XX Increases strength and hardness but reduces ductility Improves surface finish MANUFACTURING MATERIAL AISI DESIGNATION SYSTEM FOR ALLOY STEEL TYPE OF STEEL Manganese Steel Molybdenum Steels Chromium Steels Chromium - vanadium steel Nickel-ChromiumMolybdenum Steels Silicon-managanese steel ALLOY SERIES 13xx 40xx 41xx 43xx 44xx 46xx 47xx 48xx 50xx 51xx E51100 E52100 61xx 86xx 87xx 88xx 92xx APPROXIMATE ALLOY CONTENT (%) Mn 1.6 - 1.9 Mo 0.15-0.3 Cr 0.4-1.1; Mo 0.08 - 0.35 Ni 1.65-2; Cr0.4-0.9;Mo 0.2-0.3 Mo 0.45 - 0.6 Ni 0.7-2; Mo 0.15-0.3 Ni 0.9-1.2;Cr0..35-0.55;Mo0.15-0.4 Ni3.25-3.75;Mo 0.2-0.3 Cr 0.3--0.5 Cr 0.7-1.15 C 1.0;Cr 0.9-1.15 C 1.0; Cr 0.9 1.15 Cr 0.5 - 1.1; V0.1-0.15 Ni Ni Ni Si PRINCIPAL PROPERTIES Improve surface finish High Strength Hardness Great Strength and toughness Hardness and Strength COMMON USES Axles, forgings, gears Cams, mechanical parts Gears, Shafts, bearings springs, connecting rods Punches and Dies, Pistons Rods, Gears, Axles 0.4-0.7;Cr 0.4-0.6;Mo 0.15-0.25 Rust resistance, hardness Food Containers 0.4-0.7;Cr 0.4-0.6;Mo 0.2-0.3 and strength Surgical equipment 0.4-0.7;Cr 0.4-0.6;Mo 0.3-0.4 1.8 - 2.2 Springiness and elasticity Springs Steel forms • Carbon-steel sheets: flat rolled sheets made from heated slabs that are progressively reduced in size as they move through a series of rollers • Hot-Rolled Sheets • Cold-Rolled Sheets • Carbon-Steel plates • Hot-rolled bars • Cold-finished bars • Steel Wire • Pipe : specified by OD and wall thickness • Tubing: specified by OD, ID or wall thickness Structural-Steel shapes • Beams & channels: specified by depth and weight per length (lb/ft) • Angles: specified by length of legs & thickness (or lb/ft) • Tees • Zees • Wide-flange sections: specified by depth, width across flange, lb/ft More types of Steel • • • • High-Strength Low- Alloy (HSLA) Low and Medium- Alloy steels Stainless steels: corrosion resistance Free-Machining MANUFACTURING MATERIAL CONTINUOUS X X X CERAMIC MOLD X X X INVESTMENT X X PERMANENT MOLD X X X X X X X SAND X X X X X X X SHELL MOLD X X X DIE CASTING X X X X COLD HEADING X X X X DEEP DRAWING X X EXTRUDING X X FORGING X X MACHINING X X X PM COMPACTING STAMPING AND FORMING X X X X X ZINC X TITSNIUM X TIN X STEEL IRON SILVER,GOLD, PLANTINUM COPPER CENTRIFUGAL FORMING METHOD LEAD ALUMINUM MAGNESIUM METAL MOLYBDENUM COPPER, TANTALUM, TUNGSTEN COMMON METHODS OF FORMING METALS CASTING X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X Nonferrous Metals • Aluminum: 1/3 density of steel, but some alloys are stronger than steel & corrosion resistant • Copper: good conductor, corrosion resistant • Nickel • Magnesium • Zinc • Titanium • Beryllium • Refractory metals • Precious metals MANUFACTURING MATERIAL WROUGHT ALUMINUM ALLOY DESIGNATIONS MAJOR ALLOYING ELEMENT DESIGNATION Aluminum (99% or more) 1xxx Copper 2xxx Manganese 3xxx Silicon 4xxx Magnesium 5xxx Magnesium and silicon 6xxx Zinc 7xxx Other elements 8xxx Unused series 9xxx Plastics: nonmetallic materials capable of being formed or molded with heat, pressure, chemical reactions, or combination • Disadvantages of metals: corrode or rust, need lubrication, working surfaces wear readily, can’t be used as electrical or thermal insulators, opaque & noisy, when they flex they fatigue rapidly • Plastics (many) are chemical resistant, corrosion resistant, need no lubrication, quiet running, light weight, range of colors, adaptable to mass production methods, low cost • Thermoplastics soften or liquefy and flow when heat is applied • Thermosetting Plastics undergo an irreversible chemical change when heat is applied or a catalyst or reactant added • Can be machined MANUFACTURING MATERIAL COMMON TERMS FAMILY OF PLASTICS THERMOSETTING THERMOPLASTICS Alkyds ABS Allylics Acetal Resin Amino (Melamine and Urea) Acrylics Casein Cellulosics Epoxy Fluorocarbons Phenolics Nylon Polyesters (fiberglass) Polycarbonate Silicones Polyethylene Polystyrene Polypropylenes Urethanes Vinyls Rubber • Elastomers are derived from either natural or synthetic sources • Has Elastic properties. Withstands large deformations and quickly recovers shape • Mechanical rubber (tires, belts, bumpers) • Cellular rubber (pads, weather stripping, foam rubber)