PreQ ESD - 2.20 Heat treatment

Annealing uses

Preventing metal from breaking off when being bent by heating the metal to soften.

Aluminium annealing method

Put soap on the surface and heat with a blowtorch until the soap turns black

Aluminium annealing cooling

washing off the soap in cold water (400 degrees)

Steel annealing method

heat to cherry red (725 degrees)

Steel cooling

Burying the steel in sand

Copper annealing method

Heat to dull red (500 degree)

Copper cooling

cool naturally in air

Tempering use

To soften the high carbon steel after cooling it

Tempering method

Clean the area to be tempered

Head gently until colour appears

Plunge the tip into water and swirl it around

Light brown

240 degrees - for drills and milling cutters

Dark brown

270 degrees - Scissors and knives

Dark purple

290 Degrees - screwdrivers and spanners

Case hardening use

to allow mild steel to be hardened and tempered by heating the mild steel in bright red and then buried in carbon rich powder up to 2 mm