Modifications of the properties of materials (metal)

Question 1

tempering: process

Answer 1

to heat the metal to a temperature for an amount of time that will make the metal less brittle (more ductile) and much tougher.

Question 2

tempering industrial

Answer 2

• metal brought from a hot to a cold temperature quickly (quenching) to produce desired qualities in the final product.
• a big change in temp 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 other working.
• full annealing is done to give workability to such parts as forged blanks destined for use in the machine tool industry.
• annealing is done for relief of internal stresses.
• temps vary with metals, 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, depth approx 0.03mm.
• inner core left untouched and so still posses 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 is used for steels with a low carbon content.

Question 8

work hardening

Answer 8

• when a metal is cold worked: it is 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 it needs to be hardened.
• in order to keep its shape it is planished, hit over gently with a hammer.

Question 9

age hardening

Answer 9

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