Why stainlesss steel doesn’t rust

Chromium

The main reason behind why stainless steel won’t rust.

Stainless steel contains at least 10.5% chromium, which in reacting to air will create a protective layer.

Certain conditions will affect how the oxide layer forms and how well it does its job.

No oxide layer could occur with constant exposure to certain acids and constant wear.

Porous oxide layer can be the result of a dirty surface or overheating.

Oxide layer could be damaged by scrapes or impacts.

Even oxide layer provides the best corrosion resistance.

A faulty oxide layer will still cause the stainless steel to rust.

Especially after welding, it’s extremely common for stainless steel welds to rust after few months. Understandably, it’s not something easy to spot by eye, as the weld would look great at first.

Thus it’s important to passivate the metal with nitric/citric acid or with the Cleanwelds cleaning device if you want to make sure it has the best corrosion resistance.