Tempered glass blew up How did this happen?

The automatic explosion of tempered glass under the action of no direct mechanical external force is called self-explosion of tempered glass. Self-explosion is one of the inherent characteristics of tempered glass. There are many reasons for self-explosion, simply summarizing the following: 1 The effect of glass quality defects

A. There are stones and impurities in the glass: impurities in the glass are the weak points of the tempered glass, and also the stress concentration. In particular, if the stone is in the tensile stress zone of the tempered glass, it is an important factor leading to the cracking. The stone is present in the glass and has a different coefficient of expansion than the glass body. The stress concentration in the crack region around the stone after the tempering is multiplied. When the coefficient of expansion of the stone is smaller than that of the glass, the tangential stress around the stone is in a tension state. Crack propagation that occurs with stones is highly prone to occur.

B. Glass containing nickel sulfide crystals

C. The surface of the glass is scratched, blasted, deep-blasted, etc. due to improper processing or operation, which may cause stress concentration or self-explosion of the tempered glass. 2 The stress distribution in the tempered glass is uneven, and the temperature gradient generated by the offset glass in the direction of the glass thickness during heating or cooling is uneven and asymmetrical. The tempered products have a tendency to self-explosion, and some produce "wind explosion" when chilled. The tempered glass forms a self-explosion if the tensile stress zone is offset to one side of the article or offset to the surface. 3 The influence of the degree of tempering, the experiment proves that when the degree of tempering is increased to 1 level/cm, the self-explosion number is 20-25%. It can be seen that the greater the stress, the higher the degree of tempering and the larger the self-explosion.