What kind of steel is stainless steel?

　　1. What kind of steel is stainless steel?

　　Stainless steel is a kind of steel. Steel refers to steel with a carbon (C) content of less than 2% and iron with a carbon (C) content of more than 2%. During the smelting process, the addition of chromium (Cr), nickel (Ni), manganese (Mn), silicon (Si), titanium (Ti), molybdenum (Mo) and other alloying elements improves the performance of the steel, making the steel resistant corrosive.

　　2. What stainless steel has different grades?

　　During the smelting process of stainless steel, due to the different types of alloying elements added and the different amounts added, the properties of stainless steel are also different. In order to distinguish them, different steel grades are labeled. The following is the "alloying element" content table of different steel grades of common stainless steel for reference only:

　　Steel grade Carbon Silicon Manganese P Sulfur Chromium Nickel Molybdenum Copper

　　304 ≤0.08 ≤1.00 ≤2.00 ≤0.045 ≤0.03 18-20 8-10

　　301 ≤0.15 ≤1.00 ≤2.00 ≤0.045 ≤0.03 16-18 6-8

　　202 ≤0.15 ≤1.00 7.5-10 ≤0.05 ≤0.03 17-19 4-6

　　201 ≤0.15 ≤1.00 5.5-7.5 ≤0.05 ≤0.03 16-18 3.5-5.5

　　3. What kind of stainless steel is not easy to rust?

　　There are three main factors affecting stainless steel corrosion:

　　1. The content of alloy elements. Generally speaking, steel with a chromium content of 10.5% will not rust easily.

　　The higher the chromium and nickel content, the better the anti-corrosion effect. For example, the nickel content of 304 is 8-10% and the chromium content is as high as 18-20%. This kind of stainless steel will generally not rust.

　　2. The smelting process of the production company will also affect the corrosion resistance of stainless steel. Large stainless steel plants with good smelting processes, advanced equipment and advanced technology can guarantee the control of alloy elements, removal of impurities and control of billet cooling temperature. 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 plants have backward equipment and backward processes. During the smelting process, impurities cannot be removed, and the products will inevitably rust.

　　3. It is not easy to rust in the external environment, dry climate, and ventilated environment. It is easy to rust in areas with high air humidity, continuous rainy weather, or environmental areas containing acidic and alkaline air.

　　4. Stainless steel is non-magnetic. Is non-magnetic stainless steel good? If the microstrip is magnetized, wouldn’t it be 304?

　　Many customers go to the market to buy stainless steel. They bring a small magnet with them and suck it when looking at the goods. They think that stainless steel that cannot be magnetized will not rust if it is not magnetized. In fact, this is a wrong understanding.

　　Whether stainless steel belt is magnetic or not is determined by its structure. Due to different solidification temperatures, stainless steels with different structures such as "ferrite", "austenite" and "martensite" will be formed. Among them, "ferrite" and "martensite" stainless steel are magnetic, and austenite stainless steel is magnetic. Tensite stainless steel has better comprehensive mechanical properties and weldability, but only in terms of corrosion resistance, magnetic "ferritic" stainless steel is stronger than "austenitic" stainless steel. The so-called 200 series and 300 series stainless steel currently circulating in the market, which contain high manganese and low nickel, are also non-magnetic, but their performance is very different from that of 304, which contains high nickel. On the contrary, 304 will also become slightly magnetic after stretching, annealing, polishing, casting and other processes. Therefore, it is a misunderstanding and unscientific to judge the quality of stainless steel by whether stainless steel strips are magnetic or not.