Stainless steel valve stem materials are usually divided into four categories according to the matrix structure:

1. Ferritic stainless steel stem: 12% to 30% chromium. Its corrosion resistance, toughness and weldability increase with the increase of chromium content, and its resistance to chloride stress corrosion is better than other types of stainless steel valve stems.

2. Austenitic stainless steel valve stem: contains more than 18% chromium, and also contains about 8% nickel and a small amount of molybdenum, titanium, nitrogen and other elements. It has good comprehensive performance and is resistant to corrosion by various media.

3. Austenitic-ferritic duplex stainless steel stem: It has the advantages of both austenitic and ferritic stainless steel ball stems, and has superplasticity.

4. Martensitic stainless steel stem: high strength, but poor plasticity and weldability.