Our more commonly used terms
Galvanised Steel
Steel that has been through a process to receive a protective zinc coating to prevent rusting/increase corrosion resistance.
G300
Refers to the steel grade that has a minimum yield strength of 300MPa (megapascals). Megapascals is a unit that measures pressure, one megapascal is approximately equal to about 100 metric tons resting over one square metre.
Z275
Refers to the combined minimum Zinc coating mass of 275g/m2 for both sides of pre-galvanised sheet metal. So, each side would have approximately 138g/m2 zinc coating.
Z = The coating is galvanised (zinc)
275 = The total/combined mass of the coating
This process of pre-galvanising is similar to the process of hot dipped galvanising however generally takes place at the beginning of the process, so products would be cut and shaped further down the line.
Z600
For brick ties and many roofing needs, a combined minimum Zinc coating mass of 600g/m2 for both sides of pre-galvanised sheet metal is either required by Australian standards or commonly used for increased durability.
Z = The coating is galvanise (zinc)
600 = The total/combined mass of the coating
Hot Dipped Galvanised (HDG)
A common form of galvanisation. The process of dipping a steel or fabricated steel product in a molten (450 degree celcius) pool of zinc and other chemicals to add a protective coating.
It involves a process of cleaning the original material, wetting the surface of the steel and immersion into the bath along with any post treatment afterward.
Stainless Steel 304 (SS304)
This is the most common form of stainless steel. It is suited for more corrosive environments compared to HDG, but will rust and corrode when exposed to severe coastal conditions.
304 stainless steel is a member of the austenitic family of stainless steels, meaning it contains nickel in addition to chromium. To be precise, 304 stainless steel contains at least 18 percent chromium and 8 percent nickel, which is why it can be known as 18/8 steel.
Stainless Steel 316 (SS316)
This is also known as marine grade stainless steel. It is similar to the chemical make-up of SS304, however also contains molybdenum (2-3%), which makes its much more resistant to corrosion. However, this will also require regular maintenance (ie cleaning off salt), to keep its resistance.
This grade of stainless steel is particularly effective when used in acidic environments. With this metal, corrosion that is caused by acetic, hydrochloric and other forms of acids can be prevented.
Zinc-Nickel Coated
This is an alloy (combination of metals). This alloying of nickel and zinc (normally approx. 85-90% zinc, 10-15% nickel) can be up to ten times stronger than zinc alone. The process of applying this coat requires an electrical current to be applied to the metal surface, followed by the coating.
The combination of zinc and nickel created a composition that will corrode slower than zinc alone.
Salt Spray Testing
Also known as salt fog, or salt mist testing. This allows for an accelerated and accurate testing of how coastal environments can affect a product. It is conducted in a dedicated chamber which is then injected with a salt solution which has a precisely controlled pH (measuring the acidity/basicity of a solution) and salt content percentage.
Bimetallic Corrosion
Also known as Galvanic corrosion, this is an electrochemical process. When the electrical currents that each metal has are notably different, then the risk of bimetallic corrosion is high. Generally, a level of moisture will also need to be present, as well as oxygen.
This issue can be seen when stainless steel products have been cut by non-similar metals, as well as galvanised metal on a stainless steel product in a frequently wetting area. Bimetallic corrosion is an accelerated form of corrosion compared to if only one metal was present.
Electroplating
This is the process of coating, through a form of placing a metal product into a solution and applying an electrical current in order to coat the product with a thin layer of another metal by electrolysis. This is designed improve the metal’s corrosion resistance. Metals commonly used in plating include copper and nickel.