There is rust in the 304 material, which may be due to the following reasons:
First, the presence of chloride ions in the environment
Chloride ions are widely present, such as salt/sweat/seawater/sea breeze/soil. Stainless steel in the presence of chloride ions, corrosion is very fast, even more than ordinary low carbon steel.
Therefore, there is a requirement for the use environment of stainless steel, and it is necessary to wipe frequently to remove dust and keep it clean and dry.
Second, no solution treatment
The alloying elements are not dissolved in the matrix, resulting in a low content of the matrix microstructure and poor corrosion resistance.
Third, this material without titanium and niobium has a tendency to be born with intergranular corrosion.
The addition of titanium and niobium, together with a stable treatment, can reduce intergranular corrosion.
A high-alloy steel that resists corrosion in air or chemically corrosive media. Stainless steel has an aesthetically pleasing surface and good corrosion resistance. It does not require surface treatment such as plating, but also exhibits the inherent surface properties of stainless steel. One of the aspects of steel, commonly referred to as stainless steel.
From the perspective of metallography, because stainless steel contains chromium and the surface forms a very thin chromium film, this film is isolated from the intrusion of oxygen in the steel to resist corrosion.
In order to maintain the corrosion resistance inherent in stainless steel, the steel must contain more than 12% chromium.
304 is a versatile stainless steel that is widely used to make equipment and parts that require good overall performance (corrosion resistance and formability).
304 stainless steel is a grade of stainless steel produced in accordance with American ASTM standards. 304 is equivalent to China's 0Cr19Ni9Ti stainless steel. 304 contains 18% chromium, 9% nickel, carbon content ≤0:08%
304L is a variant of 304 stainless steel with a lower carbon content for applications requiring soldering. The lower carbon content minimizes the precipitation of carbides in the heat affected zone near the weld, which may result in intergranular corrosion (weld erosion) in certain environments.