Heatstrengthened

Heatstrengthened glass is a type of partially tempered glass. It is produced by reheating annealed glass to a temperature below its softening point, typically around 370 degrees Celsius, and then cooling it in a controlled manner. This process creates compressive stress on the surface of the glass and tensile stress in the interior.

The resulting glass is stronger than annealed glass but not as strong as fully tempered glass. It can withstand greater thermal loads and mechanical stresses compared to standard annealed glass. When fractured, heatstrengthened glass breaks into large shards, similar to annealed glass, rather than the small, granular pieces characteristic of fully tempered glass. This makes it less safe for applications where breakage might pose a hazard to occupants.

Heatstrengthened glass is often used in applications where increased strength and thermal resistance are desired, but the safety implications of full tempering are not required or are undesirable. Common uses include structural glazing, facades, and in some types of laminated glass where the risk of injury from broken glass is mitigated by the interlayers. It is important to distinguish heatstrengthened glass from fully tempered glass, as their mechanical properties and breakage patterns differ significantly.