Ferritic stainless steel is divided into five categories, of which categories 1-3 are standard grades and categories 4-5 are special grades. So far, the largest usage and widest range of applications are mainly concentrated in standard steel grades. Therefore, standard ferritic stainless steels are generally fully capable of meeting and adapting to the requirements of most applications.

Category 1 – Cr content: 10%-14%; typical grades 409, 410L.

This type of steel has the lowest chromium content among all stainless steels and is therefore the cheapest. It is most suitable for use in environments where there is no corrosion or slight corrosion and local slight rust is allowed. Type 409 stainless steel was originally designed for automobile exhaust system mufflers (exterior parts that are not severely corroded). Type 410L stainless steel is commonly used in containers, buses and long-distance cars, and has recently been used as the outer frame of LCD monitors.

Category 2 – Cr content: 14%-18%; typical grade 430.

It is the most widely used type of ferritic stainless steel. It contains higher chromium and has better corrosion resistance. Most of its properties are similar to 304. An alternative to Type 304 stainless steel in some applications and generally has sufficient corrosion resistance for indoor use. Typical uses include washing machine drums, interior panels, etc. Typical 430 is often used as a 304 replacement material in kitchen appliances, dishwashers, pots and pans, etc.

Category 3 – Cr content: 14%-18%, including stabilizing elements Ti, Nb, etc.; typical grades are 430Ti, 439, 441, etc.

Compared with type 2, this type of grade has good weldability and formability. In most cases, its performance is even better than 304. Typical uses include sinks, heat exchange tubes (sugar industry, energy, etc.), automobile exhaust systems (longer life than 409) and welded parts of washing machines. Category 3 grades can even replace 304 for applications with higher performance requirements.

Category 4 – Mo content is above 0.5%; typical grades include 434, 436, 444, etc.

This type of grade increases corrosion resistance by adding molybdenum. Its typical application areas are hot water tanks, solar water heaters, automobile exhaust systems, electric heating kettles and microwave oven parts, automobile decorative strips and outdoor panels, etc. The corrosion resistance of 444 stainless steel is equivalent to that of 316 stainless steel.

Category 5 – Cr content: 18%-30%; typical grades include 446, 445/447, etc.

These grades improve corrosion and oxidation resistance by adding more chromium and containing molybdenum. The corrosion resistance and oxidation resistance of this type of grade are better than 316. Typical uses Coastal and other high corrosion resistance environments. The corrosion resistance of JIS447 is equivalent to that of metallic titanium.