Self Explosion Solution For Tempered Glass To Reduce Stress Value

The distribution of stress in tempered glass is that the two surfaces of tempered glass are under compressive stress, while the core layer is under tensile stress. The stress distribution in the glass thickness is similar to a parabolic curve. The center of the glass thickness is the vertex of the parabola, which is the point where the tensile stress is maximum; There is compressive stress near the two surfaces of the glass on both sides; The zero stress surface is approximately one-third of the thickness. By analyzing the physical process of tempering and quenching, it can be seen that there is a rough proportional relationship between the surface tension of tempered glass and the maximum tensile stress inside, that is, the tensile stress is 1/2 to 1/3 of the compressive stress. Domestic manufacturers generally set the surface tension of tempered glass at around 100MPa, but the actual situation may be higher. The tensile stress of tempered glass itself is about 32MPa~46MPa, and the tensile strength of glass is 59MPa~62MPa. As long as the tension generated by the expansion of nickel sulfide is within 30MPa, it is sufficient to cause self explosion. If the surface stress is reduced, it will correspondingly reduce the inherent tensile stress of tempered glass itself, thereby helping to reduce the occurrence of self explosion.
The surface stress range of tempered glass specified in the American standard ASTMC1048 is greater than 69MPa; The semi tempered (heat strengthened) glass is between 24MPa and 52MPa. The standard BG17841 for curtain wall glass specifies a semi tempered stress range of 24<; δ≤ 69MPa. The new national standard GB15763 implemented in China. 2-2005 "Safety Glass for Building Use - Part 2: Tempered Glass" requires that the surface stress should not be less than 90MPa. This is 5MPa lower than the 95MPa specified in the old standard, which is beneficial for reducing self explosion.