Why does 304 stainless steel belt rust?

Reasons for rust: 304 materials may rust due to the following reasons:

1: There are chloride ions in the use environment. Chloride ions exist widely, such as table salt/sweat stains/sea water/sea breeze/soil, etc. Stainless steel corrodes very quickly in the presence of chloride ions, even more than ordinary low carbon steel. Therefore, there are requirements for the environment in which stainless steel is used, and it needs to be wiped frequently to remove dust and keep it clean and dry. (In this way, he can be classified as "improper use".) There is an example in the United States: a company uses an oak container to hold a solution containing chloride ions. The container has been used for nearly a hundred years and was planned to be replaced in the 1990s. , because the oak material was not modern enough, the container leaked due to corrosion 16 days after it was replaced with stainless steel.

2: No solid solution treatment. The alloy elements are not dissolved into the matrix, resulting in a low alloy content in the matrix structure and poor corrosion resistance.

3: This material, which does not contain titanium and niobium, has an inherent tendency for intergranular corrosion. Adding titanium and niobium, coupled with stabilization treatment, can reduce intergranular corrosion. A kind of high-alloy steel that can resist corrosion in the air or chemically corrosive media. Stainless steel has a beautiful surface and good corrosion resistance. It does not need to undergo surface treatment such as color plating, but can utilize the inherent surface properties of stainless steel and is used in many applications. A type of steel, often called stainless steel. Representative performance include 13 chromium steel, 18-8 chromium-nickel steel and other high alloy steels.

From a metallographic point of view, because stainless steel contains chromium, a very thin chromium film is formed on the surface. This film isolates the oxygen that intrudes into the steel and plays a role in corrosion resistance. In order to maintain the inherent corrosion resistance of 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 comprehensive properties (corrosion resistance and formability). 304 stainless steel is a brand of stainless steel produced in accordance with American ASTM standards. 304 is equivalent to my country's 0Cr19Ni9 (0Cr18Ni9) stainless steel. 304 contains 19% chromium and 9% nickel.

304 is the most widely used stainless steel/heat-resistant steel. Used for food production equipment/Xitong chemical equipment/nuclear energy, etc.: 304 corresponds to the Chinese brands 0Cr18Ni9, 1Cr18Ni9Ti, carbon content ≤0:08% 304L is a variant of 304 stainless steel with lower carbon content, used for occasions requiring welding. The lower carbon content minimizes the precipitation of carbides in the heat-affected zone close to the weld, and the precipitation of carbides may cause intergranular corrosion (welding erosion) of stainless steel in certain environments.