What is stainless steel? Which types of stainless steel are not prone to rust?

Stainless steel refers to steel that is resistant to corrosion by weak corrosive media such as air, steam, and water, and chemically corrosive media such as acids, alkalis, and salts. It is also called stainless acid-resistant steel. In practical applications, steel that is resistant to corrosion by weak corrosive media is often called stainless steel, while steel that is resistant to corrosion by chemical media is called acid-resistant steel. Due to the difference in chemical composition between the two, the former is not necessarily resistant to corrosion by chemical media, while the latter is generally rust-resistant. The corrosion resistance of stainless steel depends on the alloying elements contained in the steel.
1. The content of alloying elements.
Generally speaking, steel with a chromium content of 10.5% is not easy to rust. The higher the chromium and nickel content, the better the corrosion resistance. For example, the nickel content of 304 material is 8-10%, and the chromium content reaches 18-20%. Such stainless steel will not rust under normal circumstances.
2. The smelting process of the production enterprise will also affect the corrosion resistance of stainless steel.
Large stainless steel mills with good smelting technology, advanced equipment and advanced processes can ensure the control of alloy elements, removal of impurities and control of cooling temperature of steel billets, so the product quality is stable and reliable, the internal quality is good and it is not easy to rust. On the contrary, some small steel mills have backward equipment and backward processes. Impurities cannot be removed during the smelting process, and the products produced will inevitably rust.
3. External environment, dry and well-ventilated environment is not easy to rust.
However, areas with high air humidity, continuous rainy weather, or high acidity and alkalinity in the air are prone to rust. 304 stainless steel will also rust if the surrounding environment is too bad.