Term
| What is the most useful type of material (more so than a pure metal)? |
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Definition
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Term
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Definition
| It is a mixture of two or more materials, one of which is a metal |
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Term
| How is an alloy most commonly made |
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Definition
| An alloy is most commonly made by heating the elements to an extremely high temperature and then mixing them together to form a homogeneous substance |
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Term
| How many alloys have been developed? How many pure elements have been used to do this (there are 40 total)? Why do companies put resources into making new alloys? |
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Definition
| about 2000 alloys have been developed using between 2 and 10 of the 40 elements available. Companies put resources towards this field because alloys are more useful for than pure elements and because they lead to technological advancements |
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Term
| What are some examples of alloys? |
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Definition
Pewter (Jefferson cup) Sn + Sb + Cu
Brass Cu + Zn
Bronze Cu + Sn
Solder Sn + Pb or Sn + Ag
Dental Amalgam Ag + Sn + Hg
Steel Fe+0.1C+1Mn+1Cr+1Ni+1Mo 1
Stainless Steel Fe + 15Cr + 10Ni
Aerospace Al Al + 5Cu + 1Mg + 0.15Cr
Titanium Ti + 6Al + 4V
Superalloy Ni+20Cr+15Fe+5Al+5Ti+5W
1
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Term
| Why are alloys important? What about their properties is unique? |
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Definition
| Alloys are important to technological advancements especially in electronics and whatnot. Their properties are interesting because an alloy's properties are not the sum of its component parties. Soft tin and soft copper make hard bronze. Even melting points can change drastically between part and whole. |
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Term
| Why is the microscopic structure of an alloy important? Who studies this structure? |
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Definition
The microscopic structure is important because it controls the properties of the alloy
Those in the field of metallurgy study the structure |
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Term
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Definition
| A phase is a form of matter in which the material is completely homogeneous throughout. The crystal structure, composition and properties are all the same. The phase must also be bounded and separated from other phases |
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Term
| How does iron (Fe) change as the temperature increases? Why is this important? |
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Definition
As the temperature increases, iron will move from body-centered cubic to face-centered cubic (910 C), however, if the temperature continues to increase, the iron will transform back into BCC iron (1400 C). If it gets even hotter, it will transform into a liquid and then a gas (1539 C and 2740 C)
Each time the iron shifts its crystal lattice structure, the phase it is in changes
These phase changes are the basis for all steel technology |
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Term
| Is sugar water one phase or two phases? |
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Definition
If the sugar in the water is completely dissolved, then the solution is in one phase.
if the sugar is not completely dissolved, then the the mixture is in two phases. |
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Term
| What is a solubility limit? (use sugar water as a tenable example) |
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Definition
The solubility limit of water is the point at which there is too much sugar in the water for any more to be dissolved. At this point, if any more sugar is added, it will precipitate on (fall to) the bottom of the glass. At this point the water is supersaturated.
aka, there is a maximum amount that a certain subject can be dissolved in another substance. This will cause two phases to be in existence. |
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Term
| If you want to increase the solubility limit, how do you do it? |
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Definition
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Term
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Definition
A phase diagram is a roadmap of the various phases that can form in a multi-element/ component system for different temperatures and alloy compositions
The diagram examines the alloy when it is in equilibrium and is not in between phase changes |
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Term
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Definition
| the boundary that describes the precipitation of solid β phase in the host α is called the Solvus. Under the solvus line you will see β + α |
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Term
| what is a binary phase-diagram |
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Definition
| it is a phase diagram which only consists of two component parts |
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Term
| What were the three sources of ferrous metals available to early man? |
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Definition
| meteoric iron, native iron, and man-made ferrous metals. The third came from reducing iron from its ore |
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Term
| What do you know about meteoric iron? |
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Definition
Meteoric iron was probably the first type of iron used by the ancient people. We know this because
1. the old names for iron translate reference the sky
2. there is a high nickel content in ancient iron artifacts which matches the nickel content of meteors
3. "primitive"-moderns use this type of iron to make iron instruments |
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Term
| What do you know about telluric (native) iron? |
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Definition
| It is very rare and the only truly large deposit of it is in Greenland (that we know of). It is unlikely, therefore, that ancient people were able to use this type of iron |
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Term
| What do you know about man-made ferrous material? |
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Definition
Metallic iron can be reduced from iron ore (especially from burning charcoal).
Charcoal is composed primarily of carbon and has iron in the form of iron oxides. When oxygen is introduced at the bottom of the bed of charcoal it will combine with the carbon and create heat by forming carbon dioxide. This, because of the remaining carbon, is transformed into carbon monoxide. This CO reacts with the oxygen in the iron oxide to form CO2 which escapes, leaving wrought iron |
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Term
| How is steel formed? What is steel? |
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Definition
| Steel is an alloy consisting of iron and carbon. Carbon is added to the steel when it is at a high temperature and is in the FCC phase (between 910 and 1394 C). Expand on this topic? |
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Term
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Definition
| a hard brittle alloy that iron and carbon can from. It is also known as cemetite and Fe3C. It is a very hard, ceramic material |
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Term
| What are Pearlite, Bainite, and Martensite? |
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Definition
Pearlite: Mixture of ferrite and carbide. It is layered and is not wanted in samurai swords, however it is used in piano wire. It is associated with strength
Bainite: Also a mixture of ferrite and carbide, but without the layers. Wanted for the backbone of the samurai sword because it is very tough (i.e. stands up to abuse -- will not allow cracks to break the sword in two) To get Bainite you should cool your iron quickly to a mid-level temperature and then slowly
Martensite: Occurs after metal is quenched from a high temperature and results in the carbon being trapped inside the iron. This type of metal is very hard, but very brittle. It is used to form the cutting edge of the sword. To get this you need to cool the metal rapidly to room temperature
Each of these three have different combinations of ferrite and cementite, but with different distributions |
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Term
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Definition
| It is a complex mixture of organic compounds (primarily plant remains -- the principle elements of coke are carbon and hydrogen). This is the substance that is left over after the destructive distillation of coal |
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Term
| What is flux and what is its purpose? |
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Definition
| Flux is the material used to help septate iron from its impurities. Separating iron can be difficult because many of its impurities are difficult to melt off. The flux helps to melt the impurities and gives it something to attach to once out of the iron |
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Term
| Long Range vs. Short Range Order |
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Definition
| A long-range order structure is one in which a pattern persists over a long distance on the atomic scale. Glass is not like this. Glass has an atomic arrangement similar to that of a liquid and has a short-range order. |
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Term
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Definition
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Term
| What are modified network chain polymers? |
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Definition
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Term
| What is one naturally occurring glass? |
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Definition
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Term
| What is glass transition? |
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Definition
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Term
| Among the following three different forms of iron, malleable iron, pig iron and wrought iron, which is not useful without further treatment? What is the reason? |
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Definition
| Pig iron. It is brittle unless purified, in particular of sulfur and phosphorous |
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Term
| What are the properties of glass? |
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Definition
Glass does not solidify at specific temperatures the way crystalline solids do
Upon cooling from the melt, the glass will become more and more viscous
in glassy materials the volume decreases continually with the temperature
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Term
| Which of the following three iron-containing materials, meteoric iron, telluric iron and hematite, must be processed through a blast furnace? |
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Definition
| hematite (because it is an iron compound). |
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Term
| Iron comes primarily from: (a) Ore, (b) Coke, (c) Meteorites (d) Telluric Iron |
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Definition
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Term
| Complete the statement: Carbon is necessary in a blast furnace to make pig iron because . . . . |
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Definition
| Answer: at high temperataure it reacts with the iron ore, forming CO and CO2 and leaving behind iron. |
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Term
| The principal iron-ore deposits of North America are in |
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Definition
| the Lake Superior District |
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Term
| Question: What are the two main uses of flux in steel making and what is the chief natural flux? |
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Definition
| Flux is used (i) to render materials such as iron ore, which are difficult to melt, more easily fusible and (ii) to provide a substance with which the impurities in the iron ore may combine in preference to the metal. (iii) The chief natural flux is limestone. |
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Term
| The thermal, chemical and mechanical separation of metal from its ore is called ____________ |
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Definition
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Term
Fill in the blanks and know what the heck this says
__________ is soft and magnetic. Much less carbon dissolves in __________. Body centered cubic (bcc) is the crystal structure of __________. |
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Definition
| ferrite; ferrite; ferrite |
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Term
| Be sure you know the phase diagram for Fe-C |
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Definition
| Know it. I mean it. He's really going to ask this on the exam! |
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Term
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Definition
| Ferrite is BCC iron and it is very soft and deformable |
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Term
| How many layers does a samurai sword have? |
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Definition
experimentally 30,000
Wow! That's a lot! |
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Term
| Which two types of iron is the samurai sword made of? What two properties does this give the sword? |
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Definition
It is made of Martensite (cutting edge) and Bainite (backbone)
these two materials give the sword hardness (Martensite) and toughness (Bainite) |
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Term
| What would happen if you increased the carbon content in the sword? |
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Definition
| It would increase the hardness of the ferrite |
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Term
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Definition
an Amorphous solid
and
Viscous at elevated temperatures |
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Term
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Definition
| we did it during the last lecture |
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Term
| What is the structure of glass normally called? |
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Definition
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Term
| What is the glass transition temperature? |
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Definition
| The temperature below which glass is considered to be a solid |
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Term
| In glass materials, does volume increase continuously as temperature decreases? |
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Definition
No
as the temperature decreases, the volume will decrease as well. Water is the only material that does not follow this rule because it expands when it freezes |
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Term
| What is the difference between a crystalline and amorphous structure? |
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Definition
| The crystal remains solid up to a fixed melting point and then turns into a liquid. The amorphous material gradually softens over a broad temperature range because it has the liquid structure throughout but its viscosity rises steeply with decreasing temperature. |
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Term
| In between which two phase points is glass worked |
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Definition
| the softening point and the working point |
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Term
| Task: Discuss why glass is said to be non- crystalline and list some of the other characteristics of glasses. |
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Definition
| Glass is a class of matter, rather than a particular material. By using X-rays one can see that the structure is not crystalline and does not have Long Range Order in the atomic arrangement. Mostly glasses may be regarded as super-cooled and highly viscous liquids except that they have a transition temperature, the glass transition temperature, Tg, below which their viscosity is essentially infinite and they are proper solids. By contrast, crystals typically melt and solidify at fixed temperatures. |
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Term
| What is the major difference between glass and quartz? |
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Definition
| Quartz has a crystalline structure, where glass does not. Therefore, quartz will actually melt while glass becomes more and more viscous while the temperature rises |
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Term
| What is the ―glass transition temperature, Tg? What happens above and below Tg? Does the volume of glass increase or decrease at lower temperature? |
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Definition
| Below Tg the material is a glassy solid glass, above it is best understood as a super-cooled liquid, that with heating gradually transforms into an ever more fluid liquid. The volume decreases continuously with decreasing temperature. |
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Term
| Many materials can exist in both the glassy and the crystalline state. The difference is due to the arrangement of the atoms among each other. (a) What is that difference? (b) How can one determine this by the use of x-rays? (c) In which manner can one obtain the glassy rather than the crystalline state? |
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Definition
| (a) Glasses have no long-range order. (b) On account of lacking long-range order, glasses do not generate sharp x-ray reflection or refraction spots. (c) By quenching from the liquid state. |
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Term
What is not a characteristic of ceramic materials?
a. High melting point
b. Low thermal shock resistance
c. High strength in tension
d. High oxidation resistance
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Definition
| C is not a characteristic. Ceramic materials do not have a high strength in tension |
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Term
| What type of material is a computer chip likely to be made of? |
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Definition
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Term
| What material is likely to be used to dope a computer chip? |
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Definition
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Term
| Which material (that we've studied in this unit) were the Romans masters at? And which did they greatly advance? |
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Definition
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Term
| What type of bonding does glass use? |
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Definition
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Term
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Definition
the Eutectic is a special alloy composition where a single composition of the liquid phase freezes directly
to form two solid phases of specific compositions. Occurs at at a specific temperature rather than in a range of temperatures.
This point can be manipulated by changing the composition of an alloy.
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Term
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Definition
are used when there is a minimum of
alloying elements other than carbon. They make up a major
proportion of the steel produced, because most of our
structural steels fall into this category.
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Term
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Definition
are made with up to 5 w/o additions of
manganese, nickel, chromium and molybdenum.
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Term
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Definition
including stainless steels are designed for
severe service conditions and have a high alloy content of
chromium and nickel.
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Term
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Definition
Most tools that the average person handles, such
as hammers, saws, wrenches, pliers, etc., are not made of tool
steels, but of mass produced carbon or low-alloy steels heat
treated to give the desired combination of properties. The
products called tool steels are intended to be used for the
shaping of other metals by cutting, shearing, etc. Tool steels
commonly have high levels of those alloying elements which
form carbides (e.g. W, V, Mo, Cr), because hard stable
carbides retain their hardness under severe stress and locally
high temperatures encountered in metal-removal operations
(machining).
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Term
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Definition
When carbon is a major alloying element (3-3.5
w/o) the temperature of 100% liquid steel drops to below
2300°F (1260°C) as compared to 2800°F for pure iron. This
reduced temperature makes high-carbon alloys very adaptable
for castings. The liquid metal fills the mold readily and reacts
very little with the mold surface. Therefore it is used
extensively as cast iron.
Graphite shows up in the microstructure as flakes and weakens the iron.
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Term
| What are the materials that need to be removed from pig iron to make steel? |
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Definition
Carbon, manganese, phosphorus, sulphur, and
silicon |
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Term
| What does more carbon do to iron? |
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Definition
| It makes it harder -- think martensite. It has the carbon trapped inside and it is the hard cutting edge of the sword |
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