强化玻璃、淬火玻璃或钢化玻璃是由退火玻璃经过热处理而制成。一般强化玻璃比退火玻璃的强度高4至6倍。原因是玻璃表面的轻微裂痕都会被应力所紧压，而内层可能出现裂痕的可能性亦较低。 但是强化玻璃亦有缺点。由于玻璃内的应力需要平衡，所以如果强化玻璃上出现任何损坏或裂痕，整块玻璃就会碎成指甲大小，但同时因为会碎成没有尖角的小碎片，相对也比较安全。所以对玻璃的切割及打磨处理需在强化工序前进行。而且与退火玻璃相比，强化玻璃的硬度较低，较容易被刮花。

Toughened or tempered glass is a type of safety glass processed by controlled thermal or chemical treatments to increase its strength compared with normal glass. Tempering puts the outer surfaces into compression and the inner surfaces into tension. Such stresses cause the glass, when broken, to crumble into small granular chunks instead of splintering into jagged shards as plate glass (aka: annealed glass) creates. The granular chunks are less likely to cause injury.