A level metals

Question 1

Alloying definition

Answer 1

A parent metal combined with another substance (metal or carbon) resulting in superior properties including strength, hardness, durability etc.

Question 2

Common alloying metals for steel

Answer 2

Chromium- increased corrosion resistance, hardness and toughness

Vanadium- increases strength and toughness including wear resistance

Nickel- increased strength and hardness and corrosion resistance

Question 3

Smart alloys

Answer 3

Alloys that react to changes in the external environment eg. Nitinol which reforms to a set shape when heated ( made of nickel and titanium)

Question 4

Tungsten carbide

Answer 4

Tungsten and carbon a made into a powder then sintered (heated and pressurised extremely to produce a solid)
Cutting tools, jewellery, machinery

Pros - 2x as hard as steel and 2x density

Cons - expensive to work with, need diamond to process

Question 5

high speed steel

Answer 5

18% tungsten, chromium and vanadium are mixed with carbon steel
- higher melting point means it is used for machining bits and it is also very hard

Question 6

heat treatment

Answer 6

involves the use of heating and chilling to extreme temperatures to make a metal harder or softer

Question 7

hardening and tempering

Answer 7

• heat gradually with a torch until it is red hot
• plunge into cold water or oil

to temper:
- use emery cloth to clean the surface
- heat again to red hot
- leave to cool in air until it reaches the desired colour
- quench in water again to make it less brittle

Question 8

steel tempering colours

Answer 8

pale yellow - lathe tools - 230
dark yellow - drill bits - 250
brown - shears - 260
purple - knives - 270
dark purple - saws - 280
blue - screwdrivers - 300

Question 9

case hardening

Answer 9

works by creating a thin layer of high carbon steel that is much harder
- placed in a high carbon environment like being covered in carbon and then heated till red hot and repeat to increase the cases thickness
- allow to slowly cool

creates a hard edge but maintains a soft core

Question 10

annealing

Answer 10

softens the metal

• for steel use a torch to heat until red hot (900 degrees)
• allow to slowly cool
• for aluminium hold the torch at a distance and use soap to show when it is hot enough
• allow to slowly cool

Question 11

normalising

Answer 11

returning to its original state

• heat the steel until cherry red
• allow to cool in air

Question 12

mig welding

Answer 12

(metal inert gas)
- heat generated through an electric current
- workpiece clamped into negative electrode
- steel electrode used as filler material

Question 13

tig welding

Answer 13

(tungsten inert gas)
- heat generated by an electric arc (electrode doesn’t touch the work)
- tungsten electrode isn’t used up
- filler material added separately

Question 14

spot welding

Answer 14

• welds sheets together without filler material
• contacting sheets are joined by heat from an electric current
• workpieces held by electrodes

Question 15

oxypropane/acetalyne welding

Answer 15

uses a gas torch to melt the metal together
- oxygen and other gas ratio are altered to change the temperature of the flame

Question 16

soft soldering

Answer 16

for below 320 degrees
- tin or lead solder is added and heated by a soldering iron
- melted between two components to join them

Question 17

hard soldering

Answer 17

590-870 degrees
- used for higher MP metals
- uses a torch to melt the solder
- used in jewellery making

Question 18

brazing

Answer 18

more than 850 degrees
- heated with a torch to melt brazing rods
- used to join copper or brass