Modifications of the properties of materials (metal)

Question 1

tempering

Answer 1

to heat the material to a temperature for an amount of time that will make the material less brittle and much tougher

Question 2

tempering: industrial

Answer 2

• often a metal is brought from a hot to a cool temp quickly (quenching), to produce desired qualities in the final product
• a drastic change in temperature like this can make the metal too brittle and weak to use safely

Question 3

annealing: process

Answer 3

• treatment of a metal or alloy by heating to a predetermined temp
• holding for a certain time
• cooling to room temp to improve ductility and reduce brittleness

Question 4

annealing: industrial

Answer 4

• process annealing is carried out intermittently during the working of a piece of metal to restore ductility lost through repeated hammering or working.
• full annealing is done to give workability to such parts as forged blanks destined for use in the machine tool industry.
• also done for relief of internal stresses.
• temperatures vary with metals and alloys and with properties desired but must be within a range that prevents the growth of crystals.

Question 5

normalising

Answer 5

• undertaken on ferrous metals that have become hardened, in order to return them to their unhardened state.
• once normalised and cooled it will have lost some of its hardness and can be reworked.
• heating the product to 900oc cherry red and cooled in air

Question 6

case hardening: process

Answer 6

• carbon is added to the outer surface of the steel to a depth of approx. 0.03mm.
• inner core is left untouched and so possess properties such as flexibility and is still relatively soft.

Question 7

case hardening: industrial

Answer 7

• simple method of hardening steel.
• less complex than hardening and tempering.
• technique used for steels with a low carbon content.

Question 8

work hardening

Answer 8

• when a metal is cold worked: its bent hit or shaped over a period of time.
• as the metal is shaped it becomes hard and brittle.
• useful for copper shaping, once the desired shape is achieved it needs to be hardened. to keeps its shape, it is planished.

Question 9

age hardening

Answer 9

• ferrous metals become hard with age.
• metal will need to be normalised before it can be tempered or annealed.