There may be several reasons for rusting of stainless steel angle steel materials:

1. Chloride ions exist in the use environment.

Chloride ions are widely present, such as table salt, sweat stains, sea water, sea breeze, soil and so on. Stainless steel corrodes very quickly in the presence of chloride ions, even more than ordinary low carbon steel.

Therefore, there are requirements for the use environment of stainless steel, and it needs to be wiped frequently to remove dust and keep it clean and dry.

2. Without solution treatment.

Alloying elements are not dissolved into the matrix, resulting in low alloy content in the matrix structure and poor corrosion resistance.

3. This titanium- and niobium-free material has an inherent tendency to intergranular corrosion.

The addition of titanium and niobium, together with stabilization treatment, can reduce intergranular corrosion.

A high-alloy steel that can resist corrosion in the air or in chemically corrosive media. Stainless steel has a beautiful surface and good corrosion resistance. It does not need surface treatment such as color plating to exert the inherent surface properties of stainless steel. It is used in many applications. A type of steel, usually called stainless steel. High-alloy steels such as 13 chrome steel and 18-8 chrome-nickel steel represent performance.

From the perspective of metallography, because stainless steel contains chromium, a very thin chromium film is formed on the surface. This film isolates it from the oxygen intruded into the steel and acts as a corrosion resistance. In order to maintain the inherent corrosion resistance of stainless steel, the steel contains more than 12% chromium.