Determine cast iron butterfly valve core material must be related to the media, can be considered from the following aspects:

If it is non-corrosive media, such as water, you can use 45 other steel or other structural steel.

If it is the corrosive medium, we must know the nature, temperature, concentration and other factors of corrosion, under normal circumstances. Acidic environment must know the nature of acid, temperature, PH value of concentration, etc., or even the choice of stainless steel corrosion will occur. If it work in alkaline environment, room temperature can use carbon structural steel, high temperature, high concentrations can use stainless steel.