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World standard steels and valve steels
Common steels used in the manufacture of valves include carbon steel, stainless steel, alloy steel and low-temperature steel such as ASTM A105N and F11. The choice of valve steel depends on the particular valves, temperature, conditions and usage environment.
1. Carbon steel
Carbon steel is the earliest and most commonly used material for valves. It is also the most important material in valve production. Carbon steel valves have excellent strength and suitable cost, so they are widely used, especially in non-corrosive environments.
Carbon steel, usually referred to as commercial grade steel, is divided into grades WCB and WC6, which are low-carbon steel and high-carbon steel respectively. WCB has low carbon content, good welding performance and oxidation resistance, and is often used to make gate valves, triple eccentric butterfly valves, globe valves and check valves with relatively low working pressure. WCB is widely used in industrial production for wall thickness ≤50mm, operating temperature ≤425°C, and steam / fluid medium with working pressure ≤2.5MPa.
2. Stainless steel
Valves made of stainless steel are not corrosion resistant, but have good corrosion resistance. Generally 304 and 316 stainless steels are used to make valves. The 304 stainless steel is used to make valves with the working pressure of 6MPa and a working temperature of 200℃ or below; while the 316 stainless steel is suitable for valves that require higher temperature or pressure.
3. Alloy steels
Alloy steels refer to steels that contain other chemical elements besides carbon, such as cobalt, chromium, nickel, molybdenum, etc., and are used in combination with other metals to form alloy steels. The most commonly used alloy steels for valves are 1Cr18Ni9Ti and 0Cr18Ni9. 1Cr18Ni9Ti is a kind of steel with high strength and good plasticity, and due to its higher nickel content, its corrosion resistance is slightly better than that of 0Cr18Ni9. Its ideal temperature range is -50~450℃ and the maximum pressure range is 4MPa. 0Cr18Ni9 is a kind of stainless steel with good plasticity and corrosion resistance, and is widely used for die forging in titanium industry. Its ideal temperature range is -50~400℃ and its maximum pressure range is 10MPa.
4. Low temperature steel
Low temperature steels, commonly referred to as low temperature steels, are special steels that are made from ordinary carbon structural steels by adding chrome, nickel and copper. Low temperature steels are mainly composed of carbon, chromium, nickel, copper, molybdenum, manganese, phosphor and sulfur elements. Low temperature steels are strong, tough and ductile. There are two types of low temperature steels: ASTM A105N and F11. ASTM A105N is mainly used to make nuclear power plants and other important valve products, as well as cryogenic valves. It is widely used in working conditions under -60℃. F11 is widely used to make valves and has high strength, gooddimensional stability and excellent corrosion resistance, and is most suitable for working in medium temperatures below 550℃.
In conclusion, due to the different working conditions and application environment, valve manufacturers will choose different valve steels. The selection of valve steel should take into account not only economic factors, but also the working temperature, working pressure and corrosion resistance of the environment, so as to prolong the service life of valves.
