How are ferritic stainless steels classified?
Ferritic stainless steel can be divided into two categories: ordinary and high-purity ferrite according to whether the total carbon and nitrogen content is less than 0.05%. According to the chromium content, ordinary ferritic stainless steel is subdivided into low chromium, medium chromium and high chromium ferritic stainless steel.
The chromium content of low-chromium ferritic stainless steel is generally between 10.5% and 14%. It has the lowest chromium content among all ferritic stainless steels and is also the cheapest material. This type of stainless steel is suitable for use in slightly corrosive environments or scenes that allow local rust. For example, 409 is specially designed for automobile exhaust mufflers; 410L is used for containers and LCD display frames.
The chromium content of medium-chromium ferritic stainless steel is between 14% and 19%, and its performance is close to austenitic 304 stainless steel. It is the most widely used material in the ferritic system. Due to its high chromium content and excellent corrosion resistance, 430 is widely used in washing machine drums, dishwashers, cookers and kitchen equipment. It is the preferred alternative to austenitic 304 materials.
The chromium content of high-chromium ferritic stainless steel is between 19% and 30%. By further increasing the chromium content and adding molybdenum and other elements, the corrosion resistance and oxidation resistance are improved. This type of stainless steel has advantages over austenitic 316 stainless steel, so it is widely used in coastal buildings and corrosive environments with high chlorine content.
High-purity ferrite means that the total carbon and nitrogen content is less than 0.05%. At the same time, elements such as molybdenum, titanium, and niobium are added to increase resistance to intergranular corrosion, pitting corrosion, crevice corrosion, and welding performance. Therefore, this type of material is more commonly used in microwave oven parts, hot water tanks, solar water heaters or electric heating kettle products.
