Due to inherent characteristics of 400-series stainless steel, drawability and weldability fall below those of 304. However, drawability is improved by using extremely minute [C+N] and the ferrite-only phase is maintained by adding Nb, a ferrite stabilizing element. As a result, this new type of steel for water tanks has an improved corrosion resistance and softness as well as higher resistance to stress, corrosion, and cracking. Furthermore, the heat treatment before and after welding can be omitted. It is mostly used in large capacity water tanks, solar-powered water heater, electric water heater, and other potable water facilities.