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The performance of 904L stainless steel pipe
International names: 904L, Al-904L, UNS N08904, SUS890L, F904L, W- Nr. 1.4539, NAS 255, 00Cr20Ni25Mo4.5Cu Executive standards: ASTM A240/ASME SA-240, ASTM A276, ASTM A182/ASME SA-182, ASTM A312/ASME A312
ASTM B625/ASME B625、ASTM B673/ASME B673
Main components: carbon (C) ≤ 0.02, manganese (Mn) ≤ 2.00, nickel (Ni) 23.0 ～ 28.0, silicon (Si) ≤ 1.0, phosphorus (P) ≤ 0.045, sulfur (S) ≤ 0.035, chromium (Cr) 19.0 ～ 23.0, copper (Cu) 1.0 ～ 2.0, molybdenum (Mo) 4.0 ～ 5.0
Physical property: 904L Density: 8.24g/cm3, melting point: 1300-1390 ℃, magnetic property: none
Heat treatment: heat preservation between 1100-1150 ℃ for 1-2 hours, rapid air cooling or water cooling.
Mechanical property of 904L stainless steel pipe: tensile strength: σ B ≥ 490Mpa, yield strength σ B ≥ 215Mpa: elongation: δ≥ 35%, hardness: 70-90 (HRB)
Corrosion resistance and main use environment: 904L is a kind of austenitic stainless steel with low carbon content and high alloying designed for harsh corrosion conditions. It has better corrosion resistance than 316L and 317L, and takes into account both price and performance, with high cost performance. Due to the addition of 1.5% copper, it has excellent corrosion resistance for reducing acids such as sulfuric acid and phosphoric acid. It also has excellent corrosion resistance to stress corrosion, pitting corrosion and crevice corrosion caused by chloride ion, and has good resistance to intergranular corrosion. In the concentration range of 0-98% pure sulfuric acid, the service temperature of 904L can be as high as 40 ℃. The corrosion resistance of pure phosphoric acid in the concentration range of 0-85% is very good. In industrial phosphoric acid produced by wet process, impurities have a strong impact on corrosion resistance. Among all kinds of phosphoric acid, 904L has better corrosion resistance than ordinary stainless steel. In strong oxidizing nitric acid, 904L has lower corrosion resistance compared with high alloyed steel without molybdenum. In hydrochloric acid, 904L is used at a lower concentration of 1-2%. In this concentration range. The corrosion resistance of 904L is better than that of conventional stainless steel. 904L steel has high resistance to pitting corrosion. It can resist crevice corrosion in chloride solution. The force is also very good. The high nickel content of 904L reduces the corrosion rate at pits and crevices. When the temperature of ordinary austenitic stainless steel is higher than 60 ℃, it may be sensitive to stress corrosion in a chloride-rich environment. This sensitivity can be reduced by increasing the nickel content of stainless steel. Due to the high nickel content, 904L has high resistance to stress corrosion cracking in chloride solution, concentrated hydroxide solution and hydrogen sulfide rich environment.
The 904L stainless steel pipe has stronger corrosion resistance compared with other similar austenitic stainless steel pipes, which is mainly due to the addition of 1.5% copper element, especially for acid corrosion similar to sulfuric acid and phosphoric acid, which has very high corrosion resistance. At the same time, it is convenient for welding and processing, and has this low carbon characteristic.
In industrial phosphoric acid produced by wet process, impurities have a strong impact on corrosion resistance. Among all kinds of phosphoric acid, 904L stainless steel pipe has better corrosion resistance than ordinary stainless steel pipe. In high oxidizing nitric acid, the corrosion resistance is lower than that of high alloy steel without molybdenum. In hydrochloric acid, the use of 904L stainless steel tubes is limited to a lower concentration of 1-2%. Within this concentration range.
904L stainless steel pipe has better corrosion resistance than traditional stainless steel pipe. It has high resistance to spot corrosion. It also has good resistance to crevice corrosion in chloride solution. The high nickel content of 904L stainless steel pipe reduces the corrosion rate of pits and gaps. Ordinary austenitic stainless steel may be sensitive to stress corrosion in chloride-rich environment with temperature higher than 60 ℃. This sensitization can be reduced by increasing the nickel content of stainless steel.
Due to its high nickel content, 904L stainless steel pipe has high resistance to stress corrosion cracking in chloride solution, concentrated hydroxide solution and environment rich in hydrogen sulfide.