Does heat-treated glass mean tempered glass?

Does heat-treated glass mean tempered glass? Heat-treated glass does not necessarily imply tempered glass. Heat treatment refers to heating glass to a specific temperature range, followed by rapid cooling to increase its surface and internal compressive stress. This process can make glass stronger, more durable, and safer and give it unique properties. Tempered glass and heat-strengthened glass are two glass types produced using heat treatment.

The heat treatment process of glass generally includes two kinds of annealing and quenching. Annealing is to relieve permanent stress in the glass while quenching is to relieve thermal stress in the glass. It’s important to note that the specific treatment process and parameters used for glass heat treatment will depend on the type of glass material and design requirements. This ensures that the quality and performance of the treated glass meet the necessary standards.

What difference between these two heat-treated glass?

Tempered Glass

  • Production process: To manufacture tempered glass, the glass is heated to a high temperature (approximately 620°C) and then rapidly cooled with air. This creates a high state of compression on the surface of the glass, giving it its strength.
  • Safety: broken patterns of the tempered glass are unique. After being shattered, it becomes small fragments with relatively obtuse angles, basically without sharp corners, and will not cause significant harm to the human body. It is a kind of safety glass.
  • High Strength: Tempered glass is much stronger than annealed or untreated glass, 4-5 times stronger than annealed glass. It can meet the requirements of high-rise and super-high-rise buildings.
  • Thermal stability: Tempered glass has good thermal stability. The temperature difference that tempered glass can withstand is 2.5 to 3 times that of annealed glass.
  • Reworkability: generally cannot be reprocessed. The glass must first be cut, edged, corner-cut, drilled, etc., into the desired shape before it can be tempered.
  • Disadvantages: First, the tempered glass self-explosion due to nickel sulfide impurities in a few pieces. Secondly, the flatness of tempered glass is not as good as before tempering, and sometimes the stress lines on the tempered glass can be vaguely or even clearly seen.
  • Application: Tempered glass is safety glass, usually used in safety-conscious applications, such as high-rise buildings, doors and windows, guardrails, and other places.

Heat-strengthened Glass

  • Production process: The production process for heat-strengthened glass is similar to that of tempered glass. The glass is heat-treated (heated to a temperature of around 600°C), and its strength is increased by controlling the cooling time with a slower cooling curve.
  • Safety: When heat-strengthened glass is broken, the cracks of the whole piece of glass start to expand from the stress point to the edge, showing a radioactive state. If heat-strengthened glass falls from a building, it will cause severe injuries to people, just like ordinary glass. It’s not safety glass like tempered glass.
  • Strength: heat-strengthened glass is about twice as strong as annealed glass and not as strong as tempered glass.
  • Thermal stability: The thermal stability of heat-strengthened glass is double that of annealed glass. But lower than tempered glass.
  • Reworkability: heat-strengthened glass, like tempered glass, is also non-reworkable. When it is reprocessed, the glass will break.
  • Self-explosion: Tempered glass is self-explosive due to nickel sulfide impurities or excessive tempering, while heat-strengthened glass can easily avoid self-explosion.
  • Flatness: The bow and wave deformation of heat-strengthened glass is smaller than that of tempered glass. This better flatness is conducive to reprocessing into the heat-strengthened coated or heat-strengthened laminated glass.
  • Application: heat-strengthened glass is not considered safety glass, so a single piece of heat-strengthened glass is not commonly used in applications where safety is a concern. If it is used, it is generally made into safe laminated glass.

In conclusion

Heat treatment is a process that alters the surface properties of glass, making it stronger, more durable, and safer. However, it is essential to note that heat-treated glass does not necessarily mean tempered glass. While tempered glass is heat-treated, other types exist, such as heat-strengthened glass. It is crucial to understand the differences between these types of glass to ensure that the right style is selected for the intended application. Tempered glass, for instance, is known for its high strength and safety features, making it ideal for use in applications where safety is a concern. As a professional, it is essential to clearly understand the properties of different types of glass to make informed decisions and recommendations.