One common question we often encounter from our customers is: Why are Grade 80 and Grade 100 components not recommended to be hot dip galvanized or electro galvanized? The answer lies in the intricate interplay between material properties and the galvanization process. Let’s dive into the details to understand why these high-strength components are incompatible with hot-dip galvanizing or electro galvanizing and why do we recommend powder coating instead.
The Incompatibility of Grade 80 and Grade 100 with Hot-dip Galvanizing or Electro Galvanizing
1. Hydrogen Embrittlement
Both galvanizing processes, especially electro-galvanizing, can introduce hydrogen into the steel. This is particularly concerning for high-strength steels like Grade 80 and Grade 100, as the absorbed hydrogen can potentially lead to embrittlement. This condition significantly reduces the toughness and ductility of the steel, making it prone to failure under load or impact conditions.
2. Temperature Sensitivity
Hot-dip galvanizing involves immersing components in molten zinc at high temperatures (around 860°F or 460°C). This exposure can alter the mechanical properties of high-strength steels, potentially leading to a reduction in strength. The tempering process for these grades is done at lower temperatures, which makes them more susceptible to degradation when subjected to the heat of galvanizing.
3. Surface Preparation Issues
The surface preparation required for galvanizing can be detrimental to high-strength steels. Processes such as pickling and cleaning may compromise the integrity of the steel surface, leading to potential performance issues in critical applications.
Why Do We Recommend Powder Coating Instead?
Powder coating involves applying a dry powder that is cured under heat to form a hard finish. While it does not provide the same level of corrosion protection as hot-dip galvanizing, it can be effective for certain applications.
Here are the key reasons:
1. Avoidance of Hydrogen Embrittlement
Unlike electro-galvanizing and hot-dip galvanizing, powder coating does not introduce hydrogen into the steel. This is crucial for high-strength steels like Grade 80 and Grade 100, as hydrogen embrittlement can significantly weaken these materials, leading to premature failure under stress.
2. No Heat Treatment Interference
Grade 80 and Grade 100 components are heat-treated to achieve their exceptional strength and durability. The curing process for powder coating typically occurs at temperatures around 150°C to 200°C (300°F to 400°F), which is significantly lower than the temperatures used in hot-dip galvanizing. This ensures that the heat treatment of the components remains unaffected, preserving their mechanical properties.
3. Aesthetic Flexibility
Powder coatings are available in a wide range of colors and finishes, allowing for greater aesthetic flexibility. This capability enables manufacturers to achieve specific visual effects that may not be possible with traditional galvanizing.
Conclusion
While galvanizing is an effective method for protecting steel components from corrosion, it is not suitable for all types of steel. High-strength components like Grade 80 and Grade 100 are particularly vulnerable to the risks associated with galvanizing, including hydrogen embrittlement and heat treatment concerns. Understanding these limitations is crucial for ensuring the safety and performance of your projects.
