1. Annealing  Annealing is done to improve ductility (the ability to be drawn and extruded) and reduce brittleness.  Annealing consists of softening the metal by heating it between 30 & 50 degrees C above it upper critical point and allowing it to cool slowly.  This can be done in either hot sand, ashes of a fire or by leaving the metal in an oven or furnace until cooled.

2. Tempering  Tempering is done to remove some of the brittleness and hardness of steel after hardening.  Suitable temperatures for tempering vary considerably  Tempering by colour still provides an accurate and reliable method of dealing with plain carbon steels  Hacksaws blades 220.C Pen knifes 250.C Light brown

3. Normalising  The main purpose of normalising is to obtain a structure that is uniform throughout the work piece and is free from any ‘locked up’ stresses.  Similar to annealing, but the cooling rate is accelerated by taking the work piece from the furnace and allowing it to cool in free air.  This more rapid cooling results in a finer grain structure which in turn leads to improved physical properties and improved finishes when machining.

4. Hardening  Hardening of steels is done to increase the strength and wear properties.  Carbon steel is heated 30 & 50 degrees C above the upper critical point and then quenched quickly  The quicker the steel is cooled the harder it will be.

5. Assignment- Heat Treatment and work hardening of metals  Aim: The aim of this experiment is to test the effects of hardening then tempering a piece of medium carbon steel to a level required for a punch  Hypothesis: I predict that after hardening……..  Method: Hardening…….  Results/ Testing….After filing and hammering  Conclusion: After the results