WHAT MAKES OUR HANDLES SO IMPERVIOUS TO CORROSION?
We make our door handles from stainless steel. Our material of choice is AISI 304 steel, which consists of:
- 18% chromium,
- 8 – 9% nickel,
- the rest being mainly steel.
This type of material withstands corrosion (rusting) when exposed to both air and fresh water – i.e., ordinary use.
Corrosion can be caused when water contains salt, chlorine or acidic substances. Handles for use in such aggressive conditions are made from stainless steel with a molybdenum alloying agent. Called AISI 316, it is corrosion-resistant in saline, chlorine and acidic environments.
Alloying agents make the metal stronger
By using the right steel in the handle, we can keep the product from rusting in most environments. Stainless steel owes its special properties come from chromium, which should account for at least 12% of the total mass. In such items, a thin layer of chromium oxide invisible to the eye forms on the surface of the steel, protecting the metal from corrosion. If the oxide layer is lost, a new protective layer forms immediately thanks to the oxygen in the air.
Besides chromium, metals like nickel and molybdenum also add more corrosion resistance. Stainless steel’s ability to withstand corrosion is greater at a higher chromium, nickel and molybdenum content.
In the final phase of producing the handles, we treat the surfaces with a passivator, a compound that increases resistance to corrosion from the moment the product comes out of the plant.
What should be avoided?
Patches of rust may appear on stainless steel handles in the following cases:
- the surface is exposed to a significantly more aggressive environment than the one for which the steel in the specific category was intended. This effect is associated with heavily polluted air, saline solutions or residues of chlorine-containing cleaning products;
- the surface of the handles is polished, which allows corrosive substances from the surrounding environment and carbon steel particles to stick to the surface;
- The material’s surface has been marred by dust from polishing and other metal particles from tools used in the installation process;
- Ordinary carbon steel details were used to fasten the handles;
- the stainless steel comes into contact with components made of ordinary carbon steel in a wet or moist environment.
In the first three situations, the risk of corrosion is greater if the steel alloy has a low nickel and molybdenum content. The risk of corrosion can be significantly reduced by using AISI 316 stainless steel, which has extra molybdenum in it.
In the last three cases, the stainless steel surface is marred by rust from ordinary carbon steel.