1 IT 111 MANUFACTURING MATERIALS Lecture 3 Thomas E. Scott.

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IT 111 MANUFACTURING

MATERIALS

Lecture 3

Thomas E. Scott

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Standards Organizations

• American Society for Testing and Materials (ASTM)

• American Iron and Steel Institute (AISI)• Society of Automotive Engineers (SAE)• American Institute of Astronautics and

Aeronautics (AIAA)• NASA• Department of Defense (DOD)

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ASTM Standards provide: Letter designation for standards that include:

specifications, test methods, definitions, classification, suggested practices

– A. Ferrous Metals– B. Nonferrous Metals– C. Cement, ceramics– D. Miscellaneous

materials– E. Miscellaneous

Subjects

• F. Specific applications of materials

• G. Corrosion, deterioration

• H. Emergency Standards

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Ferrous Metals (Iron)

• In industry, iron is mainly used in the form of steel

• Steel – an iron carbon alloy with less than 2% carbon

• Cast Iron – more that 2% but less than 4% carbon

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Production of Iron

• Very little pure iron produced – Usually ingot or iron powders

• Mostly steels – with alloys carbon, silicon, nickel, chromium, manganese – Plain carbon steel – less that 1% alloying element of

carbon, silicon, and/or manganese– Low-alloy steel – have small quantities of the above

plus nickel, chromium, molydenum or others that alter the properties of steel

– High-alloy steel – have more than 5% of alloying elements

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Source of Iron (Fe)

• Ores of iron– Magnetite – contains 65% iron

• Ferric oxide (Fe2O3) and Ferrous oxide (FeO)

• Highly magnetic (Lodestone)

– Hermatite – contains 50% iron• Ferric oxide (Fe2O3)

• Commonly know as rust• Blood red

– Taconite – contains 30% iron• Green colored • Contains a lot of silica

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Refining Iron Ore

• Heat ore in a furnace where air (oxygen) has been removed– Produces coke

• Blast furnace – force air at 1100 F to permit carbon oxygen combustion– Iron melts – Slag provides a protective barrier for purified iron– Pure iron captured as ingots (Pigs)– Contains roughly 4% carbon (cast iron)

• Yield is about 50% - 6000 tons of ore to produce 3000 tons of pig iron

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Production of Steel (Conversion)

• Burn off carbon– Blow hot air across the pigs and scrap iron– Let the carbon burn– Add exact amounts of carbon and alloys– Draw off liquid into ingots

• Open Hearth – 200 tons in 12 hours• Bessemer – 25 tons in 15 minutes• Electric arc – Expensive because of

energy used (for finishing)

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Commercial Shapes of Steel

Ingots– Blooms

• Beams• Channels• Tubes

– Slabs• Plates• Pipe• Sheets• Coils

– Billets• Bars• Rods• Wire

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Commercial Shapes of

Steel

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Carbon in Steel

NAME % Carbon Example

Low 0.05-0.32 Sheet, Structural

Medium 0.35-0.55 Machinery, Re-bar, auto, aerospace

High 0.60-1.50 Machine tools, knives, hammers

Cast Iron >2.00 Castings

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Effect of carbon addition(Small increase – approx 0.1%)

• More expensive• Less ductile – more brittle• Harder• Loses machinability• Higher tensile strength• Lower melting point• Easier to harden• Harder to weld

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Characteristics of Carbon Steels

• Cold working– Plastic deformation at room temp

• Decrease thickness 4%• Increase tensile strength 50%• Work hardening results• May require heat treating

– Examples • Cold rolled steel• Cold drawn tubing

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Other elements in steel

• Aluminum– Oxygen remains in steel – undesirable– Adding aluminum (killed steel) causes oxygen

to react with aluminum and negates rust formation (good for forging and piercing)

– Aluminum also promotes small grain size and therefore, toughness

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Other elements in steel

• Manganese– Sulfur accumulates at grain boundaries –

undesirable– Causes the steel to lose strength at high temp– Manganese ties up the sulfur– Increases strength, hardenability, and

hardness

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Other elements in steel

• Boron – increases hardenability• Copper – increases corrosion resistance• Chromium – corrosion resistance and

hardenability• Niobium – increases strength• Titanium – high strength at high temp• Tungsten carbide – high hardness• Vanadium – toughness and impact resistance

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Steel

• Free Cutting – (High sulfur)– e.g., AISI 1111 up to 1151– Easy machining– Higher carbon XX44 for example, greater

hardness and flame case hardening

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Nomenclature for steels Steel – AISI and SAE

Four digit designator describes alloy contentNumber Type of Steel Number Type of Steel

10-- Plain Carbon 43-- Ni Cr Moly

11-- Sulfurized 46-- Ni Moly

12L-- Leaded 5--- Chromium

13-- Manganese 6--- Chrom Van

2--- Nickel 7--- Unused

3--- Nickel-Chromium 8--- Low-Ni Cr Moly

40-- Molybdenum 9--- Ni Cr small -Moly

41-- Chrome Molybdenum

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Nomenclature for steels

Examples1010 – Plain carbon (C = 0.1%)4030 – Steel with 0.30% Molybdenum

Standards table required to determine actual content, suggested use and properties

Web access to clarify material properties- Often have to pay for it

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Nomenclature for steels

• Table 3-B of Kazanas

• Table 3-C of Kazanas

• Table 3-D of Kazanas

• Table 3-E of Kazanas

• Table 3-F of Kazanas

• Table 3-G of Kazanas

• Table 3-H of Kazanas

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Tool Steels

• High carbon – high alloy• High wear and heat resistance

• High strength – hard• Letter classification

Type Purpose

A O W Air or Oil or Water hardening

H Hot working

M-T High-speed containing Moly or Tungsten

P Mold (plastic) Steels

S Shock resistant, med carbon, low alloy

D High Chromium

L-F Special Purpose

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Tool Steels

ExamplesW-1 – Water hardening 1% carbon used for

cold working of metals

D3 – High chromium with 2.25% carbon for cold working applications

S2 – Shock resistant hammer or chisel steel

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Tool Steels

• Table 3-I of Kazanas

• Table 3-J of Kazanas

• Table 3-K of Kazanas

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Tool Steels

• Must sustain high loads• Often loads concentrated on surface• May have elevated temperatures• Often substantial shock loading• Must be immune to cracking

Often particular steel alloy typesSeven basic types of tool steel

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Tool Steels

• Properties for tool steels– Wear resistance– Impact resistance– High temperature capability– Toughness

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Alloys in tool steels

• Carbon – hardenability (>0.6%)• Manganese – reduce brittleness (<0.6%)• Silicon – for hot forming, strength and toughness

(<2%)• Tungsten – hot hardness• Vanadium – hardness and wear resistance• Molybdenum – deep hardening, toughness• Cobalt – hot hardness• Chromium – hardenability (up to 12%)• Nickel – toughness and wear resistance

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Cast Iron

• More than 2% carbon

• Lower strength since carbon flakes produce minute cracks

• Very susceptible to breaking (brittle)

• Grey cast iron – almost no ductility

• White cast iron – 1% silicon making it hard

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Nodular Cast Iron

• Nodular cast iron – small amounts of calcium, cerium, lithium, magnesium, sodium

• Slow cooling produces spheres instead of plates

• Improves ductility – 60:40:20 – Tensile 60K, Yield 40K, 20% elongation

• Engine blocks, pistons, crankshafts

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Stainless Steel

• Normal Steels corrode rapidly if left uncoated

• Higher temperature, more rapid corrosion

• Chromium and nickel slow corrosion

• Stainless steels have Cr > 12%

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Stainless Steel

• Ferritic – can be strengthened by work hardening– Jewelry, utensils, automotive trim

• Austenitic – non-magnetic– 18/8 – 18% Cr, 8% Ni– Low carbon – low strength– Food utensils

• Martensitic – High strength – Knives,

• Maraging – superalloys, contain Moly and Titan

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Stainless Steel

• Numbering system– 200’s and 300’s – Austenitic– 400’s – Ferritic and Martensitic

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Corrosion (Rust)

• Galvanic corrosion (electrolytic process)

• Corrosion sped up by– Temperature– Metal fatigue– Cold working

• Retarded by– Alloys– Coatings