1
Q
Metals can be classified into two main groups. What are they?
A
- Ferrous metals
- Non-ferrous metals
2
Q
What are ferrous metals?
A
A ferrous metal contains iron (ferrite) and carbon.
3
Q
What is a non-ferrous metal?
A
A non-ferrous metal does not contain iron.
4
Q
What is a ferrous alloy?
A
Ferrous alloys are a mixture of two or metals - at least one of which contains iron and carbon.
5
Q
What is a non-ferrous alloy?
A
A non-ferrous alloy is a mixture of two or more metals - none of which contain iron.
6
Q
Name four ferrous metals.
A
- Cast Iron
- Mild Steel
- Medium Carbon Steel
- High carbon steel
7
Q
Name at least five non-ferrous metals.
A
- Aluminium
- Copper
- Lead
- Tin
- Zinc
- Titanium
- Platinum
- Gold
- Silver
8
Q
Name three ferrous alloys.
A
- Stainless steel
- High speed steel
- Die (tool) steel
9
Q
Name three non-ferrous alloys.
A
- Brass
- Bronze
- Duralumin
10
Q
Gold is the only metal found in a useable form. All other metals are extracted from ores. Which ores contain the following metals - iron, copper, aluminium, lead, tin, zinc?
A
- Iron is found in magnetite and haematite
- Copper is found in chalcopyrite
- Aluminium is found in bauxite
- Lead is found in galena
- Tin is found in cassiterite
- Zinc is found in zinc blende
11
Q
What is added to iron to strengthen it? What is this material called?
A
- Iron is combined with carbon to produce steel.
- The amount of carbon determines the strength and hardness of the steel.
12
Q
What are the two most common metal ores?
A
- Aluminium is the earth’s most common ore (bauxite).
- Iron is the second most abundant metal ore.
To find out more click here and here
13
Q
The structure of all metals are made from what?
A
Crystals
Each crystal has a boundary that is firmly bonded to the boundary of a neighbouring crystal.
14
Q
How is iron converted from either haematite or magnetite ore?
A
- The ore is heated in a blast furnace.
- The impurities (slag) are removed from the surface.
- The material produced is called “pig iron”.
- Pig iron is then converted into steel by adding carbon in a basic oxygen furnace.
To find out more click here and here and here
15
Q
What effects are produced by increasing the carbon content in irons and steels?
(see the “Properties of materials” deck for key word definitions)
A
- The material becomes harder
- Toughness is reduced and the material becomes more brittle. Cast Iron can be brittle under impact.
- Medium and High Carbon steels can be heat treated to make them stronger and harder. The material can then be used for cutting tools (mild steel has insufficient carbon to be heat treated).
16
Q
What is the carbon content % of Mild Steel?
A
Less than 0.3%
17
Q
What is the carbon content % of Medium Carbon Steel?
A
0.3 to 0.6%
18
Q
What is the carbon content % of High Carbon Steel?
A
0.6 to 1.7%
19
Q
What is the carbon content % of cast iron?
A
3.5%
20
Q
Name at least three uses for mild steel.
A
- Nuts
- Bolts
- Washers
- Car body panels
- Panels for fridge freezers and other white goods
21
Q
Name two uses for medium carbon steel.
A
- Springs
- General gardening tools
22
Q
Name at least three uses for high carbon steel.
A
- Hand tools
- Scribers
- Dot Punches
- Chisels
- Plane blades
23
Q
Name at least three uses for cast iron.
A
- Castings
- Manhole covers
- Engine blocks
- Machine parts
- Brake Discs
- Vice jaws
24
Q
Although aluminium ore (bauxite) is the most abundant ore in the Earth’s crust, it is not the most processed metal - steel is. Why?
A
Aluminium is difficult to process, required large amounts of energy. It is therefore more expensive to produce.
25
Name three common uses for **aluminium.**
* Saucepans
* Overhead power cabels
* Engine blocks
* Brake calipers
* Car Body panels
* Aircraft parts
26
Name three common uses for **copper.**
* Electric contacts
* domestic water pipe work
* electrical cable
* jewellery
27
Name three common uses for **gold.**
* Jewellery
* Electronic components
* Switch and cable contacts
* SIM cards
28
Name a common use for **lead.**
* Flashing on roofs - where the tiles meet the brickwork
29
Name two common uses for **platinum.**
* Expensive jewellery
* Thermocouple cables
30
Name two common uses for **silver.**
* Expensive cutlery
* Jewellery
* Solder
* Ornaments
31
Name two common uses for **tin.**
* Coating for steel food cans
* food wrapping (foil)
32
Name two common uses for **titanium.**
* Hip replacements
* spectacle frames
* aerospace parts due to it's high strength to weight ratio
33
Name at least three common uses for **zinc.**
* A coating for steel (galvanising and zinc plating)
* buckets
* electrical unit casings
* lock mechanisms
* high detail die castings
34
List at least four benefits of **alloying** metals.
* changes the **melting point**
* changes the **colour**
* increases **strength, hardness and ductility**
* enhances resistance to **corrosion and oxidation**
* changes **electrical/thermal** properties
* improves **flow** properties, producing better castings
## Footnote
For more information [click here](http://www.technologystudent.com/joints/alloys1.html)
35
What is **oxidation?**
**Oxidation** is an oxide layer that forms on a metal surface when in contact with oxygen. In most metals this protects the surface from further oxidation but in steels, it is **porous** and results in further oxidation and corrosion.
36
What metals are **alloyed** to produce **duralumin** and what is it commonly used for?
* **Duralumin** is an alloy of **aluminium** and **4% copper, 1% manganese and 0.1% magnesium**.
* It is used for structural components on aircraft.
37
What metals are **alloyed** to produce **brass** and what is it commonly used for?
* **Brass** is an alloy of **copper** and **35% zinc**.
* It is used for cast valves, taps, boat fittings and ornaments.
38
What metals are **alloyed** to produce **bronze** and what is it commonly used for?
* **Bronze** is an alloy of **copper** and **10% tin**.
* It is used for statues, coins and bearings.
39
What metals are **alloyed** to produce **nitinol** and what is it commonly used for?
* **Nitinol** is made from **nickel and titanium**
* It is a **smart metal** alloy used in **springs and muscle wires**
For more info [click here](http://www.technologystudent.com/equip1/sma1.htm) and [here](http://www.technologystudent.com/equip1/sma2.htm)
40
Which metals can be alloyed with steel to produce **High Speed Steels (HSS)?**
* Tungsten
* Chromium
* Vanadium
* Cobalt
41
What are the properties of **high speed steels** and what are they used for?
* **HSS**s are very hard and will cut at very high temperatures
* Therefore they are used for cutting tools such as **drills**
42
What are the properties of **high tensile steels** and what are they used for?
* **High tensile steels** have a good tensile strength and toughness and are generally corrosion resistant.
* They are used for car engine components.
43
Which metal is **alloyed** with steel to produce **high tensile steel?**
* Nickel
44
Which three metals are **alloyed** with steel to produce **stainless steel?**
* Chromium
* Nickel
* Magnesium
45
What are the properties and uses of **stainless steel**?
* **Stainless steel** is tough, durable and corrosion resistant
* It is used for sinks, cutlery and sanitary ware.
46
Which two metals are **alloyed** with steel to produce **tool and die steel?**
* Chromium
* Manganese
47
What are the properties of **tool and die steels** and what are they used for?
* **Tool and die steels** are very hard and tough with excellent wear resistance.
* They are used for fine press tools, extruder dies, blanking punches and dies, some hand tools.
48
Explain the term **work hardening.**
**Work hardening** occurs when metals are "cold worked" such as bending, rolling or hammering. The crystal structure of the metal is distorted causing internal stresses that make the metal harder.
49
How do you return **work hardened** metal to a "soft" state?
The metal must be **annealed.**
For information on **annealing** [click here](http://www.technologystudent.com/equip1/heat3.htm)
50
What is **planishing?**
**Planishing** is the term given to a beaten decorative finish in a metal such as copper or silver. The hammering **work hardens** the material.
51
List at least four **heat treatment** processes.
* Annealing
* Hardening
* Tempering
* Normalising
* Quenching
* Case Hardening
* Carburising
* Nitriding
* Flame hardening
* Induction hardening
52
What is the definition of **heat treatment?**
**Heat treatments** are processes to heat and cool metals in a controlled way to achieve a beneficial change in the properties of the materials.
53
What is **annealing?**
**Annealing** is a metal heat treatment process that reverses the internal stresses caused by work hardening. By heating the metal, the crystals grow making the material **softer** and more **ductile**. The temperature must be maintained for a sufficient period of time to allow the material to **"soak".** The material is then cooled slowly allowing the crystals to keep their new shape.
Glass can also be annealed.
For more information [click here](http://www.technologystudent.com/equip1/heat3.htm)
54
When working with steel, what is **hardening** and how is it achieved?
**Hardening** is a heat treatment that changes the way the carbon within the steel affects the strength and hardness of the material. The carbon in the structure moves out of its normal position and when the material is **quenched**, the carbon does not have time to return to its original place. This causes the material to be strengthened and hardened.
## Footnote
For more information [click here](http://www.technologystudent.com/equip1/heat1.htm)
55
What is **tempering** and why is it an important process to carry out after **hardening** medium and high carbon steels?
**Tempering** is carried out after hardening to remove any brittleness in the hardened steel. First the hardened steel is cleaned to a shiny grey colour and then heat is applied to the correct **tempering colour**. The material is then rapidly cooled (quenched). Without tempering the steel could well fail by cracking or shattering.
## Footnote
For more information [click here](http://www.technologystudent.com/equip1/heat1.htm)
56
How can you tell the what the **tempering temperature** is and what happens to the steel as the temperature rises?
The **tempering temperature** is determined by the colour of the steel. At 230ºC the steel is a pale straw colour. At 300ºC it is blue. This is known as the **tempering colour.** As the temperature rises the steel's hardness is reduced but the toughness is increased.
## Footnote
[Click here](http://www.technologystudent.com/equip1/heat1.htm)to view a **tempering colour** chart.
57
What is **quenching?**
**Quenching** is the rapid cooling of heat treated metals. Sometimes the quenching media (brine, water, oil or air) is agitated to prevent rapid localised cooling that might result in cracks.
58
What is **normalising** and how is it achieved?
**Normalising** is a heat treatment process where the **crystal structure** is allowed to become a uniform size. The metal is heated to a specific temperature where the crystal structure begins to change. The temperature is maintained (**soaked**) until all the crystals have been normalised. After cooling in air, the metal is **tougher** and more **ductile**.
59
What type of steels can be **case hardened**?
**Low carbon** steels such as **mild steel** are suitable for **case hardening**.
60
What is **case hardening** and what types of product benefit from the process?
* **Case hardening** is the hardening of the surface/outer skin of a low carbon steel.
* Cams and gears benefit from case hardening as it is only the surface that needs to be hard, leaving the remainder of the component in a less brittle state.
## Footnote
For more information [click here](http://www.technologystudent.com/equip1/heat2.htm)
61
List four different ways of **case hardening** mild steel.
* Carburising
* Nitriding
* Flame hardening
* Induction hardening
62
Explain the **case hardening** process of **carburising**.
In **carburising** the steel is placed in a ceramic box packed with carbon rich material and then heated to produce a carbon layer. Then the steel is heated to around 760ºC and then quenched to produce a hard case.
63
List two advantages of **case hardening** mild steel.
* Steels that have too little carbon for heat treatment can be given a hardened surface.
* The process leaves a tough inner core, making it suitable for camshafts, gears, steering components, all of which take a lot of wear.
64
Name one disadvantage of **case hardening**.
In most cases **grain-growth** occurs which increases the size of the steel. A machining process is then required to return the steel to its required size.
65
**Nitriding** is another **case hardening** process. Explain how its done.
In **nitriding**, steel is immersed in nitrogen whilst being heated to 500ºC. No additional hardening is necessary.
66
List at least three advantages of **nitriding.**
* No additional hardening is necessary.
* It removes the chance of surface cracks.
* It increases resistance to corrosion.
* It is a clean process.
* It is economical for large numbers.
67
Name two disadvantages of **nitriding.**
* Initial set up costs are high.
* If overheated there is a permanent loss of hardness.
68
Name two advantages of case hardening by **flame hardening** or **induction hardening.**
* A localised area of the product can be hardened leaving other area unaffected where toughness is required.
* Grain growth does not occur so no additional machining is required.
Product Design
flashcards
Decks in class (19)
# Cards
-
Composite Materials2
-
Plastics38
-
Metals68
-
Properties of Materials13
-
Metal Processes76
-
Plastics Processes1
-
Woods13
-
Component Identification5
-
Smart and Modern Materials0
-
Material Testing0
-
Plastic Processes0
-
Joining Processes0
-
Material Corrosion0
-
Material Finishes0
-
Glass & Ceramics0
-
Paper and Board0
-
Sustainability & the Environment0
-
Ergonomics and Anthropometrics0
-
Inclusive Design0
