The following heat treatments alter the properties of metals Steel can be treated by intense heat to give it different properties of hardness and softness. (only high carbon steel can be hardened and tempered).

Hardening If steel is heated until it glows red and is quenched (dipped) in clean water immediately, it becomes very hard but also brittle. This means it is likely to break or snap if put under great pressure. In a school workshop most heat treatment of metals takes place on a brazing hearth

is a heat process where is metal is heated to a specific temperature /colour and then allowed to cool slowly Annealing a heat treatment that alters the microstructure of a material causing changes in properties such as strength and hardness and ductility This softens the metal which means it can be cut and shaped more easily. Mild steel, is heated to a red heat and allowed to cool slowly. Aluminium will melt if heated for too long.

As a rule they are heated and allowed to cool slowly are relatively soft can be cut and shaped more easily They bend easily when pressure is applied. As a rule they are heated and allowed to cool slowly Difficult to cut and shape. Very difficult if not impossible to bend. As a rule they are heated and cooled very quickly by quenching in clean, cold water.

TEMPERING Tempering is a heat treatment technique for metals, alloys and glass Tempering is achieved by a controlled reheating of the material piece to a temperature below its lower critical temperature (melts) The temperatures used in tempering are often too low to be gauged by the colour of the workpiece. In this case, the blacksmith will heat the work piece for a known amount of time.

heated again to a red colour is a simple method of hardening steel. It is less complex than hardening and tempering. Case Hardening Carbon is added to the outer surface of the steel. One advantage of this method of hardening steel is that the inner core is left untouched and so still processes properties such as flexibility and is still relatively soft. steel is heated to red heat heated again to a red colour plunged into case hardening compound (high in carbon ) and allowed to cool a little. plunged into cold, clean water