In the process of valve opening and closing, the valve stem is subjected to pulling, pressing, and torsion forces, and is in direct contact with the medium. At the same time, there is relative frictional movement between the filler and the filler. Therefore, the stem material must ensure that there is sufficient temperature at the specified temperature. Strength and impact toughness, a certain degree of corrosion resistance and scratch resistance, as well as good craftsmanship.
Commonly used stem materials are the following.
First, carbon steel
When used in water and steam media with low pressure and medium temperature not exceeding 300°C, A5 ordinary carbon steel is generally used.
For medium and medium temperature and medium temperature not exceeding 450 °C water, steam medium, generally choose 35 high-quality carbon steel.
Second, alloy steel
Medium pressure and high pressure, medium temperature does not exceed 450 °C of water, steam, petroleum and other media, the general choice of 40Cr (chrome steel).
For high pressure, medium temperature does not exceed 540 °C water, steam and other media, the choice of 38CrMoALA nitriding steel.
For high pressure, steam medium medium temperature does not exceed 570 °C, the general choice of 25Cr2MoVA chromium molybdenum vanadium steel.
Third, stainless acid-resistant steel
For medium pressure and high pressure, non-corrosive medium with medium temperature not exceeding 450°C and weak corrosive medium, 1Cr13, 2Cr13, 3Cr13 chromium stainless steel can be used.
When used in corrosive media, Cr17Ni2, 1Cr18Ni9Ti, Cr18Ni12Mo2Ti, Cr18Ni12Mo3Ti and other acid-resistant steels and PH15-7Mo precipitation hardened steels are available.
Fourth, heat-resistant steel
For high temperature valves with medium temperature not exceeding 600°C, 4Cr10Si2Mo martensitic heat-resistant steel and 4Cr14Ni14W2Mo austenitic heat-resistant steel are available.