Stainless steel are magnetic like carbon steel. They are problematic to weld due to grain growth in the heat affected zone which reduces ductility and may result in cracks. Increasing chromium and molybdenum contents increase corrosion resistance as it does for austenitic stainless steels, however, this high alloying results in the precipitation of embrittling intermetallic phase upon welding. These microstructural problems due to welding restrict the use of ferritic stainless steels to very thin thicknesses and thus are not used in the construction of large heavy walled vessels and tanks, and structures like austenitic stainless steels. Common ferritic grades are: Type AISI
SAE 304 stainless steel by SAE International as part of its SAE steel grades. Outside of the US it is commonly known as A2 stainless steel, in accordance with ISO 3506 for fasteners. In the commercial cookware industry it is known as 18/8 stainless steel. In the unified numbering system it is UNS S30400. The Japanese equivalent grade of this material is SUS304.. It is also specified in European norm 1.4301. 304 stainless steel has excellent resistance to a wide range of atmospheric environments and many corrosive media. It is subject to pitting and crevice corrosion in warm chloride environments and to stress corrosion