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Tempered glass is obtained by cutting the common annealed glass into the required size, heating it to about 700 degrees near the softening point, and then cooling it quickly and uniformly.

After tempering, uniform compressive stress is formed on the surface of the glass, while tensile stress is formed inside, which improves the bending and impact strength of the glass. Its strength is about four times higher than that of ordinary annealed glass. The tempered glass that has been tempered cannot be cut, ground or damaged, otherwise it will be crushed due to the destruction of the uniform compressive stress balance.