Heat strengthened glass is less liable to breakages
In general the strength can be increased to as much as one and a half times that of the equivalent thickness of annealed glass. However, the heat strengthening process does not affect the modulus of elasticity of the product and care should be taken to limit excess deflection.
It offers greatly increased resistance to both sudden temperature changes and temperature differentials up to 100K compared with annealed glass, up to 40K. The stress characteristics of toughened safety glass, of normal soda-lime silica composition, are unchanged for continuing service up to 200°C
In the event of breakage heat strengthened glass breaks in manner similar to annealed glass.
Heat strengthened glass Performance under accidental human impact
Heat strengthened glass due to its breakage behaviour can not be classified according to EN 12600; for its pendulum impact performance. This product should not be used in critical locations (see BS 6262-4:2005)
Thermally treated glass – Processing restrictions
The characteristics of toughened and heat strengthened glass preclude any cutting or processing after manufacture. All holes and shapes must, therefore, be specified before ordering.