Youngstown State University Lecture Summary 1 Lecture Topic: Materials – Fundamentals of...

Youngstown State University

Fundamentals of Material Properties Part 4- Common Engineering Materials

Darrell WallaceYoungstown State University

2 January 14, 2006


Categories of Steel Alloys

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Steel Alloys can be divided into five groups

Carbon Steels High Strength Low Alloy Steels Quenched and Tempered Steels Heat Treatable Low Alloy Steels Chromium-Molybdenum Steels


SteelThe American Iron and Steel Institute (AISI) defines

carbon steel as follows: Steel is considered to be carbon steel when no

minimum content is specified or required for chromium, cobalt, columbium [niobium], molybdenum, nickel, titanium, tungsten, vanadium or zirconium, or any other element to be added to obtain a desired alloying effect; when the specified minimum for copper does not exceed 0.40 per cent; or when the maximum content specified for any of the following elements does not exceed the percentages noted: manganese 1.65, silicon 0.60, copper 0.60. Carbon steels are normally classified as shown below.

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Steel – Low Carbon Low-carbon steels contain up to 0.30 weight

percent C. The largest category of this class of steel is flat-rolled products (sheet or strip) usually in the cold-rolled and annealed condition. The carbon content for these high-formability steels is very low, less than 0.10 weight percent C, with up to 0.4 weight percent Mn. For rolled steel structural plates and sections, the carbon content may be increased to approximately 0.30 weight percent, with higher manganese up to 1.5 weight percent.

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Steel – Medium / High Carbon Medium-carbon steels are similar to low-carbon

steels except that the carbon ranges from 0.30 to 0.60 weight percent and the manganese from 0.60 to 1.65 weight percent. Increasing the carbon content to approximately 0.5 weight percent with an accompanying increase in manganese allows medium-carbon steels to be used in the quenched and tempered condition.

High-carbon steels contain from 0.60 to 1.00 weight percent C with manganese contents ranging from 0.30 to 0.90weight percent.

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Steel – High-Strength Low Alloy High-strength low-alloy (HSLA) steels, or

microalloyed steels, are designed to provide better mechanical properties than conventional carbon steels. They are designed to meet specific mechanical properties rather than a chemical composition. The chemical composition of a specific HSLA steel may vary for different product thickness to meet mechanical property requirements. The HSLA steels have low carbon contents (0.50 to ~0.25 weight percent C) in order to produce adequate formability and weldability, and they have manganese contents up to 2.0 weight percent. Small quantities of chromium, nickel, molybdenum, copper, nitrogen, vanadium, niobium, titanium, and zirconium are used in various combinations.

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Steel Alloy Designations

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Chromium Molybdenum steels

41xx Cr 0.50-0.95 Mo 0.12-0.30

Nickel Chromium Molybdenum steels

43xx Ni 1.82 Cr 0.50-0.80 Mo 0.25

47xx Ni 1.05 Cr 0.45 Mo 0.20 – 0.35

86xx Ni 0.55 Cr 0.50 Mo 0.20

Nickel Molybdenum steels 46xx Ni 0.85-1.82 Mo

0.2048xx Ni 3.50 Mo 0.25Chromium steels 50xx Cr 0.27- 0.6551xx Cr 0.80 – 1.05

http://www.materialsengineer.com/E-Alloying-Steels.htm

Carbon Steels 10xx Plain Carbon11xx Resulfurized12xx Resulfurized and

rephosphorizedManganese steels 13xx Mn 1.75Nickel steels 23xx Ni 3.525xx Ni 5.0Nickel Chromium Steels 31xx Ni 1.25 Cr 0.65-

0.8032xx Ni 1.75 Cr 1.0733xx Ni 3.50 Cr 1.50-

1.5734xx Ni 3.00 Cr 0.77

AISI Designations for Steel Alloys


Effects of Steel Alloying Elements

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•Carbon has a major effect on steel properties. Carbon is the primary hardening element in steel. Hardness and tensile strength increases as carbon content increases up to about 0.85% C as shown in the figure above. Ductility and weldability decrease with increasing carbon.

•Manganese is generally beneficial to surface quality especially in resulfurized steels. Manganese contributes to strength and hardness, but less than carbon. The increase in strength is dependent upon the carbon content. Increasing the manganese content decreases ductility and weldability, but less than carbon. Manganese has a significant effect on the hardenability of steel.

•Phosphorus increases strength and hardness and decreases ductility and notch impact toughness of steel. The adverse effects on ductility and toughness are greater in quenched and tempered higher-carbon steels. Phosphorous levels are normally controlled to low levels. Higher phosphorus is specified in low-carbon free-machining steels to improve machinability.



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•Sulfur decreases ductility and notch impact toughness especially in the transverse direction. Weldability decreases with increasing sulfur content. Sulfur is found primarily in the form of sulfide inclusions. Sulfur levels are normally controlled to low levels. The only exception is free-machining steels, where sulfur is added to improve machinability.

•Silicon is one of the principal deoxidizers used in steelmaking. Silicon is less effective than manganese in increasing as-rolled strength and hardness. In low-carbon steels, silicon is generally detrimental to surface quality.

•Copper in significant amounts is detrimental to hot-working steels. Copper negatively affects forge welding, but does not seriously affect arc or oxyacetylene welding. Copper can be detrimental to surface quality. Copper is beneficial to atmospheric corrosion resistance when present in amounts exceeding 0.20%. Weathering steels are sold having greater than 0.20% Copper.



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•Lead is virtually insoluble in liquid or solid steel. However, lead is sometimes added to carbon and alloy steels by means of mechanical dispersion during pouring to improve the machinability.

•Boron is added to fully killed steel to improve hardenability. Boron-treated steels are produced to a range of 0.0005 to 0.003%. Whenever boron is substituted in part for other alloys, it should be done only with hardenability in mind because the lowered alloy content may be harmful for some applications.•Boron is a potent alloying element in steel. A very small amount of boron (about 0.001%) has a strong effect on hardenability. Boron steels are generally produced within a range of 0.0005 to 0.003%. Boron is most effective in lower carbon steels.



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•Chromium is commonly added to steel to increase corrosion resistance and oxidation resistance, to increase hardenability, or to improve high-temperature strength. As a hardening element, Chromium is frequently used with a toughening element such as nickel to produce superior mechanical properties. At higher temperatures, chromium contributes increased strength. Chromium is a strong carbide former. Complex chromium-iron carbides go into solution in austenite slowly; therefore, sufficient heating time must be allowed for prior to quenching.

•Nickel is a ferrite strengthener. Nickel does not form carbides in steel. It remains in solution in ferrite, strengthening and toughening the ferrite phase. Nickel increases the hardenability and impact strength of steels.

•Molybdenum increases the hardenability of steel. Molybdenum may produce secondary hardening during the tempering of quenched steels. It enhances the creep strength of low-alloy steels at elevated temperatures.



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•Aluminum is widely used as a deoxidizer. Aluminum can control austenite grain growth in reheated steels and is therefore added to control grain size. Aluminum is the most effective alloy in controlling grain growth prior to quenching. Titanium, zirconium, and vanadium are also valuable grain growth inhibitors, but there carbides are difficult to dissolve into solution in austenite.

•Zirconium can be added to killed high-strength low-alloy steels to achieve improvements in inclusion characteristics. Zirconium causes sulfide inclusions to be globular rather than elongated thus improving toughness and ductility in transverse bending.

•Niobium (Columbium) increases the yield strength and, to a lesser degree, the tensile strength of carbon steel. The addition of small amounts of Niobium can significantly increase the yield strength of steels. Niobium can also have a moderate precipitation strengthening effect. Its main contributions are to form precipitates above the transformation temperature, and to retard the recrystallization of austenite, thus promoting a fine-grain microstructure having improved strength and toughness.



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•Titanium is used to retard grain growth and thus improve toughness. Titanium is also used to achieve improvements in inclusion characteristics. Titanium causes sulfide inclusions to be globular rather than elongated thus improving toughness and ductility in transverse bending.

•Vanadium increases the yield strength and the tensile strength of carbon steel. The addition of small amounts of Vanadium can significantly increase the strength of steels. Vanadium is one of the primary contributors to precipitation strengthening in microalloyed steels. When thermomechanical processing is properly controlled the ferrite grain size is refined and there is a corresponding increase in toughness. The impact transition temperature also increases when vanadium is added.•All microalloy steels contain small concentrations of one or more strong carbide and nitride forming elements. Vanadium, niobium, and titanium combine preferentially with carbon and/or nitrogen to form a fine dispersion of precipitated particles in the steel matrix.


Stainless Steels General Information Stainless steels are high-

alloy steels that have superior corrosion resistance than other steels because they contain large amounts of chromium. Stainless steels can contain anywhere from 4-30 percent chromium, however most contain around 10 percent. Stainless steels can be divided into three basic groups based on their crystalline structure: austenitic, ferritic, and martensitic. Another group of stainless steels known as precipitation-hardened steels are a combination of austenitic and martensitic steels.

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http://www.efunda.com/materials/alloys/stainless_steels/stainless.cfm


Stainless Steels Ferritic grades: Ferritic stainless steels are

magnetic non heat-treatable steels that contain chromium but not nickel. They have good heat and corrosion resistance, in particular sea water, and good resistance to stress-corrosion cracking. Their mechanical properties are not as strong as the austenitic grades, however they have better decorative appeal.

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Stainless Steels Martensitic grades: Martensitic grades are

magnetic and can be heat-treated by quenching or tempering. They contain chromium but usually contain no nickel, except for 2 grades. Martensitic steels are not as corrosive resistant as austenitic or ferritic grades, but their hardness levels are among the highest of the all the stainless steels.

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Stainless Steels Austenitic grades: Austenitic stainless steels are non-

magnetic non heat-treatable steels that are usually annealed and cold worked. Some austenitic steels tend to become slightly magnetic after cold working. Austenitic steels have excellent corrosion and heat resistance with good mechanical properties over a wide range of temperatures. There are two subclasses of austenitic stainless steels: chromium-nickel and chromium-manganese-low nickel steels. Chromium-nickel steels are the most general widely used steels and are also known as 18-8(Cr-Ni) steels. The chromium nickel ratio can be modified to improve formability; carbon content can be reduced to improve intergranular corrosion resistance. Molybdenum can be added to improve corrosion resistance; additionally the Cr-Ni content can be increased.

18 http://www.efunda.com/materials/alloys/stainless_steels/stainless.cfm


Tool Steels Tool steels typically have excess carbides (carbon alloys)

which make them hard and wear-resistant. Most tool steels are used in a heat-treated state, generally hardened and tempered. There are a number of categories assigned by AISI (American Iron and Steel Institute), each with an identifying letter:

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Aluminum – General Information Aluminum is a silverish white metal that has a

strong resistance to corrosion and like gold, is rather malleable. It is a relatively light metal compared to metals such as steel, nickel, brass, and copper with a specific gravity of 2.7. Aluminum is easily machinable and can have a wide variety of surface finishes. It also has good electrical and thermal conductivities and is highly reflective to heat and light.

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Aluminum - Characteristics At extremely high temperatures (200-250°C) aluminum alloys tend to lose

some of their strength. However, at subzero temperatures, their strength increases while retaining their ductility, making aluminum an extremely useful low-temperature alloy. Aluminum alloys have a strong resistance to corrosion which is a result of an oxide skin that forms as a result of reactions with the atmosphere. This corrosive skin protects aluminum from most chemicals, weathering conditions, and even many acids, however alkaline substances are known to penetrate the protective skin and corrode the metal.

Aluminum also has a rather high electrical conductivity, making it useful as a conductor. Copper is the more widely used conductor, having a conductivity of approximately 161% that of aluminum. Aluminum connectors have a tendency to become loosened after repeated usage leading to arcing and fire, which requires extra precaution and special design when using aluminum wiring in buildings.

Aluminum is a very versatile metal and can be cast in any form known. It can be rolled, stamped, drawn, spun, roll-formed, hammered and forged. The metal can be extruded into a variety of shapes, and can be turned, milled, and bored in the machining process. Aluminum can riveted, welded, brazed, or resin bonded. For most applications, aluminum needs no protective coating as it can be finished to look good, however it is often anodized to improve color and strength.

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Aluminum Alloy Designations

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Designation

Major Alloying Element

1xxx Unalloyed (pure) >99% Al

2xxxCopper is the principal alloying element, though other elements (Magnesium) may be specified

3xxxManganese is the principal alloying element

4xxx Silicon is the principal alloying element

5xxxMagnesium is the principal alloying element

6xxxMagnesium and Silicon are principal alloying elements

7xxx

Zinc is the principal alloying element, but other elements such as Copper, Magnesium, Chromium, and Zirconium may be specified

8xxxOther elements (including Tin and some Lithium compositions)

9xxx Reserved for future usehttp://www.materialsengineer.com/E-Aluminum.htm


Aluminum Alloy Characteristics

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1xxx Series. These grades of aluminum are characterized by excellent corrosion resistance, high thermal and electrical conductivities, low mechanical properties, and excellent workability. Moderate increases in strength may be obtained by strain hardening. Iron and silicon are the major impurities.

2xxx Series. These alloys require solution heat treatment to obtain optimum properties; in the solution heat-treated condition, mechanical properties are similar to, and sometimes exceed, those of low-carbon steel. In some instances, precipitation heat treatment (aging) is employed to further increase mechanical properties. This treatment increases yield strength, with attendant loss in elongation; its effect on tensile strength is not as great. The alloys in the 2xxx series do not have as good corrosion resistance as most other aluminum alloys, and under certain conditions they may be subject to intergranular corrosion. Alloys in the 2xxx series are good for parts requiring good strength at temperatures up to 150 °C (300 °F). Except for alloy 2219, these alloys have limited weldability, but some alloys in this series have superior machinability.

http://www.materialsengineer.com/E-Aluminum.htm



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3xxx Series. These alloys generally are non-heat treatable but have about 20% more strength than 1xxx series alloys. Because only a limited percentage of manganese (up to about 1.5%) can be effectively added to aluminum, manganese is used as major element in only a few alloys.

4xxx Series. The major alloying element in 4xxx series alloys is silicon, which can be added in sufficient quantities (up to 12%) to cause substantial lowering of the melting range. For this reason, aluminum-silicon alloys are used in welding wire and as brazing alloys for joining aluminum, where a lower melting range than that of the base metal is required. The alloys containing appreciable amounts of silicon become dark gray to charcoal when anodic oxide finishes are applied and hence are in demand for architectural applications.




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7xxx Series. Zinc, in amounts of 1 to 8% is the major alloying element in 7xxx series alloys, and when coupled with a smaller percentage of magnesium results in heat-treatable alloys of moderate to very high strength. Usually other elements, such as copper and chromium, are also added in small quantities. 7xxx series alloys are used in airframe structures, mobile equipment, and other highly stressed parts. Higher strength 7xxx alloys exhibit reduced resistance to stress corrosion cracking and are often utilized in a slightly overaged temper to provide better combinations of strength, corrosion resistance, and fracture toughness.



Copper Alloys

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Copper alloys are commonly used for their electrical and thermal conductivities, corrosion resistance, ease of fabrication, surface appearance, strength and fatigue resistance. Copper alloys can be readily soldered and brazed, and a number of copper alloys can be welded by arc, and resistance methods. Color of copper alloys is a significant reason for using them for decorative purposes. For decorative parts, conventional copper alloys having specific colors are readily available.

Copper is used extensively for cables and wires, electrical contacts, and a wide variety of other parts that are required to pass electrical current. Coppers alloys are used for automobile radiators, heat exchangers, and home heating systems. Because of copper alloys corrosion resistance they are used for pipes, valves, and fittings in systems carrying potable water, process water, or other aqueous fluids.

Along with ease of fabrication, some of the principal selection criteria for copper alloys are:• Corrosion resistance • Electrical conductivity • Thermal conductivity • Color and surface appearance


Copper Alloys

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Corrosion resistance of copper alloys is good in many environments, however copper alloys may be attacked by some common reagents and environments. Pure copper resists attack under some corrosive conditions. Some copper alloys, on the other hand, sometimes have inadequate performance in certain environments.Stress corrosion cracking most commonly occurs in brass. Brasses containing more than 15% Zn are the most susceptible.

Dealloying is another form of corrosion that affects zinc containing copper alloys. During dezincification of brass, selective removal of zinc results in gradual replacement of sound brass by weak, porous copper. Unless stopped the metal is weakened and liquids or gases may be capable of leaking through the porous structure.

Electrical and thermal conductivity of copper and its alloys are relatively good. This is why copper is the most commonly used electrical conductor. Alloying decreases electrical conductivity to a greater extent than thermal conductivity. This is why copper and high-copper alloys are preferred over other copper alloys when high electrical or thermal conductivity is required.


Common Copper Alloys

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Name Alloying elements

Coppers Cu

Brasses Cu-Zn

Leaded brasses Cu-Zn-Pb

Tin brasses Cu-Zn-Sn-Pb

Phosphor bronzes Cu-Sn-P

Leaded phosphor bronzes Cu-Sn-Pb-P

Copper-phosphorus and copper-silver-phosphorus alloys

Cu-P-Ag

Aluminum bronzes Cu-Al-Ni-Fe-Si-Sn

Silicon bronzes Cu-Si-Sn

Copper-nickels Cu-Ni-Fe

Nickel silvers Cu-Ni-Zn

Youngstown State University29

Resistance Properties of Common Copper Alloys

Alloy r a Notes

Pure Cu 1.67 0.00404

Electrolytic Cu

1.71 0.00397 ETP Copper

Oxygen Free Cu

1.71 N/A OF Copper

1.0% Pb 1.76 N/AFree Machining Copper

5% Zn 3.1 0.00231Gilding Metal

15% Zn 4.7 0.00160 Red Brass

30% Zn 6.2 0.00148Cartridge Brass

35% Zn 6.4 N/AYellow Brass

5% Sn 11 N/APhosphor Bronze

30% Ni 37 0.00048Cupro Nickel

mW*cm 1/K

20C http://www.gbint.com/Files/Apps/Alloy%20Table/Alloy%20Table.htm


Titanium

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Titanium Alloys The density of Titanium is roughly 55% that of steel. Titanium alloys are

extensively utilized for significantly loaded aerospace components. Titanium is used in applications requiring somewhat elevated temperatures . The good corrosion resistance experienced in many environments is based on titanium’s ability to form a stable oxide protective layer. This makes titanium useful in surgical implants and some chemical plant equipment applications.

Unalloyed (commercially pure) titanium can be found in two crystallographic forms:

Hexagonal close-packed (hcp) or alpha (α) phase is found at room temperature

Body centered cubic (bcc) or beta (ß) phase is found above 883 °C (1621 °F)

The control of alpha (α) and beta (ß) phases through alloying additions and thermomechanical processing is the basis for the titanium alloys used by industry today. It is also the primary method for classifying titanium alloys. Titanium alloys are categorized as either alpha (α) alloys, beta (ß) alloys, or alpha+beta (α+ß) alloys. One of the primary effect of alloying elements used in titanium production is the affect on the alpha to beta transformation temperature. Some elements raise the alpha to beta transformation temperature thereby stabilizing the alpha crystal structure. While other elements lower the alpha to beta transformation temperature thereby stabilizing the beta crystal structure. The effect of some elements is shown below:

http://www.materialsengineer.com/E-Titanium.htm


Titanium

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One of the primary effect of alloying elements used in titanium production is the affect on the alpha to beta transformation temperature. Some elements raise the alpha to beta transformation temperature thereby stabilizing the alpha crystal structure. While other elements lower the alpha to beta transformation temperature thereby stabilizing the beta crystal structure. The effect of some elements is shown below:

Element Effect Aluminum alpha stabilizer Tin alpha stabilizer Vanadium Beta stabilizer Molybdenum Beta stabilizer Chromium

Beta stabilizer Copper Beta stabilizer Alpha alloys commonly have creep resistance superior to beta alloys. Alpha

alloys are suitable for somewhat elevated temperature applications. They are also sometimes used for cryogenic applications. Alpha alloys have adequate strength, toughness, and weldability for various applications, but are not as readily forged as many beta alloys. Alpha alloys cannot be strengthened by heat treatment.

Beta alloys have good forging capability. Beta alloy sheet is cold formable when in the solution treated condition. Beta alloys are prone to a ductile to brittle transition temperature. Beta alloys can be strengthened by heat treatment. Typically beta alloys are solutioned followed by aging to form finely dispersed particles in a beta phase matrix.

Alpha + beta alloys have chemical compositions that result in a mixture of alpha and beta phases. The beta phase is normally in the range of 10 to 50% at room temperature. Alloys with beta contents less than 20% are weldable. The most commonly used titanium alloy is Ti-6Al-4V, an alpha + beta alloy. While Ti-6Al-4V is fairly difficult to form other alpha + beta alloys normally have better formability.

Alpha + beta alloys can be strengthened by heat treatment. When strengthening alpha + beta alloys the components are normally quickly cooled from a temperature high in the alpha-beta range or even above the beta transus. Solution treatment is then followed by aging to generate an proper mixture of alpha and transformed beta. Heat treatment is dependent on the cooling rate from the solution temperature and can be affected by the size of the component.



Titanium

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Some of the uses of titanium alloys: Surgical Implants Prosthetic devices Jet engines Chemical processing plants Pulp and paper industry Marine applications Sports equipment



Unified Numbering System (UNS)

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UNS Series Metal A00001 to A99999 Aluminum and aluminum alloys C00001 to C99999 Copper and copper alloys D00001 to D99999 Specified mechanical property steels

E00001 to E99999 Rare earth and rare earthlike metals and alloys

F00001 to F99999 Cast irons

G00001 to G99999 AISI and SAE carbon and alloy steels (except tool steels)

H00001 to H99999 AISI and SAE H-steels J00001 to J99999 Cast steels (except tool steels) K00001 to K99999 Miscellaneous steels and ferrous alloys L00001 to L99999 Low-melting metals and alloys

M00001 to M99999 Miscellaneous nonferrous metals and alloys

N00001 to N99999 Nickel and nickel alloys P00001 to P99999 Precious metals and alloys

R00001 to R99999 Reactive and refractory metals and alloys

S00001 to S99999 Heat and corrosion resistant (stainless) steels

T00001 to T99999 Tool steels, wrought and cast W00001 to W99999 Welding filler metals Z00001 to Z99999 Zinc and zinc alloys

http://www.materialsengineer.com/E-UNS-designations.htm


Polymer Vocabulary

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additive Any substance that is added to a plastic during manufacturing in order to improve its properties.

butyl A type of elastomer that is often used to make airtight products. chloroprene A type of elastomer that effectively resists oil, weather, heat, and flame. Chloroprene

was one the first successful synthetic rubbers. cross-linking The development of primary bonds that form between polymer molecules. Elastomers

are slightly cross-linked; thermosets are heavily cross-linked. elastomer A formation of a thermoplastic or thermoset that can stretch and then return to its original

shape without permanent deformation. Elastomers are only slightly cross-linked. Filler An additive that is used to partially replace a plastic material and reduce its cost. macromolecule An incredibly large molecule that consists of repeating molecular units. mer The basic molecular unit that combines in long chains to form polymers. molecule The smallest unit into which a material can be divided without changing its properties. A

molecule consists of a group of atoms held together by strong primary bonds. natural polymer A polymer resulting from raw materials found in nature. natural rubber A natural elastomer that is extracted as a sap from tropical trees. Natural rubber must

be vulcanized for commercial use. phenolic A type of thermoset known for its chemical stability and ability to maintain its desired

dimensions. plastic A material consisting of very large molecules characterized by light weight, high corrosion

resistance, high strength-to-weight ratios, and low melting points. Most plastics are easily shaped or formed. plasticizer An additive that is used to add softness and flexibility to a plastic in order to facilitate the manufacturing process.

Polyester A type of thermoset that is commonly combined with other polymers for numerous commercial uses.

rubber.

http://www.toolingu.com/class_class_desc.aspx?class_ID=500240


Polymer Vocabulary

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polyethylene A type of thermoplastic known for being both chemically inert and inexpensive. Polyethylene is the most popular commercial plastic.

polymer A material made of very large molecules that generally does not have a crystalline structure. Polymer is a more technical term for a plastic.

polypropylene A type of thermoplastic known for being very lightweight. polystyrene A type of thermoplastic that is both transparent and easily shaped. polyurethane A type of plastic that is often chemically complex. Polyurethane can be manufactured as both a thermoset

and an elastomer. polyvinyl chloride A type of thermoplastic that can be manufactured to produce both rigid and flexible materials. primary bond A bond that forms between atoms and that involves the exchanging or sharing of electrons. secondary bond A bond that involves attraction between molecules. Unlike primary bonding, there is no transfer or

sharing of electrons. shellac A resinous substance secreted from a particular beetle that is used to coat floors and furniture. Shellac is a

natural polymer. silicone A type of thermoset known for being both heat resistant and water repellant. stabilizer An additive that is used to help prevent a plastic from breaking down due to exposure to adverse

environments. steel A metal consisting of iron and up to 2.11% carbon, usually with small amounts of manganese, phosphorus, sulfur,

and silicon as well. strength-to-weight ratio The relationship between a material's strength and its weight. Materials that are light but also

very strong have a high strength-to-weight ratio. synthetic polymer A polymer that is chemically manufactured from separate materials. Synthetic polymers require

human intervention. thermal conductivity The ability of a material to conduct heat. thermoplastic A type of plastic that can be softened by heat, hardened by cooling, and then softened by heat over and

over again. Thermoplastics are not cross-linked. thermoset A type of plastic that is permanently hardened by cooling. Thermosets are heavily cross-linked. vulcanization A manufacturing process that uses additives and chemicals along with heat and pressure to increase the

number of cross-linked bonds in an elastomer. Vulcanization adds strength and toughness to a rubber.

http://www.toolingu.com/class_class_desc.aspx?class_ID=500240


Epoxy Epoxy has been mass-produced since 1946. - It is a

thermoset polyadduct. - Applications: Used in reactive molding compounds. Also used in adhesives. - General properties: It is air curable, highly fillable, possesses low shrinkage and low susceptibility to stress formation. Good adhesion to almost all materials. High tensile and vibrational strength. High heat resistance, high heat deformation resistance, and high chemical attack resistance. Good aging properties. Good electrical and dielectrical properties. Odorless, tasteless, low flammability. Systems can be formulated to meet specific requirements. - Trade Name: Acme, Aerolam, Basoset, Beckopx, Conapoxy, Corlar, Cycom, DER, Desmobond, Dobeckot, Dynopon, Ecco, Epikote, Epocast, Epodite, Eprosin, Eurepox, Exatron, Grilonit, Hysol, Isochembond, Lekutherm, Lopox, Nikalet, Paraplex, Quartrex, Scotchcast, Synthane.

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http://www.efunda.com/materials/polymers


PTFE (Teflon) Fluoroplastics, also known as PTFE, or FEP,

PFA, CTFE, ECTFE, ETFE, has been mass-produced since 1950. - It is a thermoplastic polymer. - Applications: Used in applications needing excellent dielectric strength, chemical, and temperature resistance. - General properties: It has low mechanical strength and is expensive. Very low coefficient of friction. - Trade Name: Teflon.

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Phenol-formaldehyde (Phenolic) Phenol-formaldehyde Plastic, also known

as PF, or Phenolic, has been mass-produced since 1909. - It is a thermoset polycondensate. - Applications: The first volume-produced synthesized polymer resin, PF was used in early consumer electronic products such as telephones and radios. - General properties: A naturally brittle material in pure form, it is able to be strengthened with fillers such as wood pulp and cellulose. - Trade Name: Bakelite.

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Polyamide (Nylon) Polyamide, also known as PA, or Nylon, has

been mass-produced since 1935. - It is a thermoplastic polycondensate. - Applications: Used to make high-lubricity parts (e.g. bearings, blow moldings, and clothing fabric). - General properties: It has high lubricity and moderate strength. It is tough, inexpensive, and has poor dimensional stability due to water absorption (hygroscopic nature). - Trade Name: Ultramid, Zytel.

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Polycarbonate (Lexan) Polycarbonate, also known as PC, has been

mass-produced since 1958. - It is a thermoplastic polycondensate. - Applications: Used to make optical lenses, windows, medical items, CD's, and power tool housings. Also used in truck cabs. - General properties: It has excellent strength and toughness. It possesses good dimensional stability, dielectric strength, flame retardancy, and impact resistance (highest among transparent rigid materials). It is susceptible to stress cracking with aromatic solvents, and is difficult to machine. - Trade Name: Lexan, Makrolon.

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Polyethylene Polyethylene, also known as PE, has been

mass-produced since 1939. - It is a thermoplastic polymer. - Applications: The largest volume commodity plastic, PE is used in blow-molded beverage bottles, auto gas tanks, and extruded pipe. - General properties: It has good toughness at low temperatures and is inexpensive. - Trade Name: Marlex, Alathon, Hostalen.

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Polyurethane Polyurethane, also known as PU, has been

mass-produced since 1940. - It is a thermoplastic or thermoset, (typically reinforced), polyadduct. - Applications: Used in automotive structural members, computer housings, furniture, and packaging foams. - General properties: It has high impact resistance, dielectric strength, chemical resistance, and abrasion resistance. It can be made into films, solid moldings, or flexible foams. Becomes brittle with outdoor exposure. - Trade Name: Estane, Pellanthane.

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Silicone Silicone, also known as SI, has been mass-

produced since 1943. - It is a thermoset polycondensate. - Applications: Used in computer chips, IC, cooking ware, and food containers. - General properties: It possesses dimensional stability and good electrical and dielectrical properties over wide frequency and temperature ranges. It has flame resistance, low water absorption, moderate thermal shock resistance, and average polymeric mechanical properties. It has a high cost, limited shelf-life, and a long curing time. - Trade Name: Baysilon, Blu-Sil, Commex, Fiberite, Lamitex, Siltemp, Textolite.

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Youngstown State University Lecture Summary 1 Lecture Topic: Materials – Fundamentals of...

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