Metals

EnggChem M2U2

Metals

opaque, lustrous elements that are good conductors of heat and electricity

Luster

Property of a metal that makes it reflect light

Steels

Alloys of Fe and C, but may contain other elements

Low Alloy

Types of Alloy steels

Plain Carbon Steel

Very low content of alloying elements and small amounts of Mn

Low Carbon Steel

Most abundant grade of steel

Low Carbon Steel

Not responsive to heat treatment, cold working is needed to improve strength

Low Carbon Steel

Good weldability and machinability

High Strength Low Alloy steel

Contains alloying elements such as Cu, V, Ni, and Mo up to 10%, has higher strength and can be heat treated

0.3-0.6%

Carbon content of medium carbon steel

Medium Carbon Steel

Most often used in tempered conditions, low hardenability, can be heat treated. heat treated alloys are stronger but have low ductility

0.6-1.4%

Carbon content of high carbon steel

High Carbon Steel

Hardest but least ductile steel, used in hardened and tempered condition

Cr, V, W

Strong carbide formers added to High Carbon Steel to form carbides of these metals.

Stainless Steel

Group of steels that contain at least 11% Cr and exhibits extraordinary corrosion resistance

Ferritic Stainless Steel

Stainless steel composed of alpha ferrite (BCC)

Martensitic Stainless Steel

Stainless steel that can be heat treated

Austenitic Stainless Steel

Stainless steel that is most corrosion resistant

Precipitation-Hardening Stainless Steel

Stainless steel that has ultra high-strength

Duplex Stainless Steel

Stainless steel Ferrite + Austenite

Manganese, Phosphorus, Sulfur, Silicon, Copper, Nickel, Molybdenum

Alloying elements

Manganese

Improves: Strength, Hardness
Decreases: Ductility Weldability
Affects hardenability of Steel

Phosphorus

Improves: Strength, Hardness
Decreases: Ductility
Decreases notch impact toughness of steel

Sulfur

Decreases: Ductility Weldability
Decreases notch impact toughness of steel. Found in the form of sulfide inclusions

Silicon

One of the principal deoxidizers used in steel making. In low-carbon steels, it is generally detrimental to surface quality

Copper

Detrimental to hot-working steels. Beneficial to corrosion resistance (>0.20%)

Nickel

Improves: Impact Strength, Hardenability
Ferrite strengthener

Molybdenum

Increases: Hardenability
Enhances the creep resistance of low-alloy steels

Cast Irons

lower melting point due to the presence of eutectic point at 1153 degree Celsius, have low shrinkage, good fluidity, and casting ability

Grey Cast Iron

Contains graphite in the form of flakes, weak and brittle in tension, excellent damping ability and wear resistance

Grey Cast Iron

C: 3-4%, Si: 1-3%

Nodular Iron

Addition of Mg and/or Ce to grey iron which converts graphite flakes into nodules. Normally a pearlite matrix and is stronger and ductile than grey iron

White Cast Iron

Is a result of faster cooling, most of the carbon is in the form of cementite, very hard and brittle, used as an intermediate to produce malleable cast iron

White Cast Iron

C: 2.5-3%, Si: 0.5-1.5%

Malleable Cast Iron

Produced by heating white iron to an extent which causes the decomposition of cementite into graphite

Malleable Cast Iron

C: 2.3-2.7%, Si: 1-1.75%

Compact Graphite Iron

Microstructure and properties are between grey and ductile iron. It is as castable as grey iron, has higher tensile strength and some ductility. Relatively high thermal conductivity, good resistance to thermal shock, lower oxidation at elevated temperatures.

Copper

One of the earliest metals discovered by man. Ductile, soft, and malleable which makes it hard to machine. Very high electrical conductivity but is only second to silver.

Brass, Bronze, Beryllium Copper

Copper alloys

Brass

Alloy of Cu and Zn. Easy to cast because of its low melting point and high fluidity.

Bronze

Alloy of Cu with Sn, Pb, Al, Si, and Ni. One of the earliest alloys to be discovered since Cu ores contain Sn. Stronger than brass with good corrosion resistance and tensile properties, can be cast, hot and cold worked.

Beryllium Copper

Cu alloy that is heat treatable. Cast alloys: higher Be, Wrought alloys: lower Be and some Co. Ductile, weldable, machinable, and resistant to non-oxidizing acids, abrasive wear, and galling.

75%

Percentage of Cu in US Nickels

Brass

Used for musical instruments (good ductility and acoustic properties)

Bronze

- Ancient Chinese cast artifacts
- Skateboard ball bearings
- Surgical and dental instruments

Beryllium Copper

- Springs, load cells, and other parts subjected to repeated loading
- Low current contacts for batteries and electrical connectors
- Cast alloys are used in injection molds
- Jet aircraft landing gear bearings, bushings, and percussion instruments

Aluminum

Light metal, has a wide variety of surface finishes, good electrical and thermal conductivities, highly reflective to heat and light. Easily machinable and versatile metal

Al-Li alloys

lightest among all Al alloys

Titanium

Has high affinity to oxygen, strong deoxidizer and can catch on fire and cause severe damage. 40% lighter than steel and 60% heavier than aluminum. Excellent corrosion resistance due to the presence of a thin oxide surface film. Can be used as a biomaterial

Titanium

- Aircraft
- Sporting equipment, chemical processing, desalination, turbine engine parts, valve and pump parts, marine hardware
- Medical implants: prosthetic devices
- Bikes and automotives

Titanium Alloys

- Marine and chemical processing equipment
- Gas turbine engine casting rings, compressor disc, rocket engine case, prosthetic implants

Nickel

High density, high strength, ductile, corrosion resistant, and has high temperature properties. Excellent catalytic property.

Ni-Co

used as a low-cost substitute for Pt catalysts for fuel cells

Ni-base super alloys

unique class of materials possessing exceptionally high temperature strength, creep and oxidation resistance

Ni-Ti, Cu-Al-Ni

Shape memory alloys that can go back to their original form

Ni-Cd, Ni-metal hydrides

used in batteries

Magnesium

Lightest among commonly used metals. Very reactive and readily combustible in air which allows it to be used as a lighter or fire starter. Thermal conductivity is less than Al. Has adequate atmospheric resistance and moderate strength. Since it has a favorable atomic size, it is often alloyed with many elements. Its alloys are impact and dent resistant, have good damping capacity.

Gold

Shiny, soft, heavy, rare, corrosion resistant metal. Often alloyed with silver or some other metal to make it harder when used in jewelry or money. Slightly less conductive than Cu and Ag but is highly resistant to corrosion.

Silver

Soft, white, lustrous metal that exhibits the highest electrical and thermal conductivity, and reflectivity of any metal.