Topic 3.1: Processes, techniques and specialist tools

Question 1

Hardening

Answer 1

Medium and high carbon steels are heated then held at a certain temperature for a given time, then quenched in water, oil or saltwater baths.

The process increases the hardness but also increases brittleness.

Question 2

Tempering

Answer 2

This reduces some of the excess hardness and brittleness from a hardened metal and increases the toughness and ductility.

the metal is heated to below the critical point for a given time then slowly air cooled.

The exact temperature the metal is heated to will determine the amount of hardness removed.

Question 3

Case hardening

Answer 3

This process hardens the surface of steels which have less than 0.4 percent carbon content.

Case hardening produces an outer surface which has improved hardness and resistance to surface indentation, while the inner core of the metal retains the original properties.

Question 4

Annealing

Answer 4

The heating and slow cooling of work hardened metal to make it easier to work. less brittle and more ductile.

Question 5

Normalising

Answer 5

Used on low carbon steels to give the metal a uniform, fine-grained structure (often carried out after the metal has been hot worked into a shape).

Material is heated to about the same temperature as for hardening. quickly quenched then left to cool.

It makes the metal more ductile, with increased toughness.

Question 6

Alloying

Answer 6

An alloy is a metal made of two or more metals, or combining two or more elements, one of which must be a metal.

An alloy gives enhanced properties over either of the original metals.

Alloys are produced in either a furnace or in a casting process.

The metals to be combined are melted together in specific quantities and then poured into bars or ingots to be used for. future products.

Question 7

Offset lithography