2507 S32750 1.4410 Resistance to Corrosion
2507 Duplex Steel is highly resistant to uniform corrosion by organic acids such as formic and acetic acid. It is also highly resistant to inorganic acids, especially if they contain chlorides. Alloy 2507 is highly resistant to carbide-related intergranular corrosion. Due to the ferritic portion of the duplex structure of the alloy it is very resistant to stress corrosion cracking in warm chloride containing environments. Through additions of chromium, molybdenum and nitrogen localized corrosion such as pitting and crevice attack are improved. Alloy 2507 has excellent localized pitting resistance.
The high chromium and molybdenum content of SAF 2507 makes it extremely resistant to uniform corrosion by organic acids like formic acid and acetic acid. SAF 2507 also provides excellent resistance to inorganic acids, especially those containing chlorides.
In dilute sulfuric acid contaminated with chloride ions, SAF 2507 has better corrosion resistance than 904L, which is a highly alloyed austenitic stainless steel pipe grade specially designed to resist pure sulfuric acid.
Stainless steel tube of type 316L (2.5%Mo) cannot be used in hydrochloric acid due to the risk of localized and uniform corrosion. However, SAF 2507 can be used in dilute hydrochloric acid. Pitting need not be a risk in the zone below the borderline in this figure, but crevices must be avoided.
Intergranural Corrosion
SAF 2507’s low carbon content greatly lowers the risk of carbide precipitation at the grain boundaries during heat treatment; therefore, the alloy is highly resistant to carbide-related intergranular corrosion.
Stress Corrosion Cracking
The duplex structure of SAF 2507 provides excellent resistance to chloride stress corrosion cracking (SCC). Because of its higher alloy content, SAF 2507 is superior to 2205 in corrosion resistance and strength. SAF 2507 is especially useful in offshore oil and gas applications and in wells with either naturally high brine levels or where brine has been injected to enhance recovery.
Pitting Corrosion
Different testing methods can be used to establish the pitting resistance of steels in chloride-containing solutions. The data above were measured by an electrochemical technique based on ASTM G 61. The critical pitting temperatures (CPT) of several high-performance steel in a 1M sodium chloride solution were determined. The results illustrate the excellent resistance of SAF 2507 to pitting corrosion. The normal data spread for each grade is indicated by the dark gray portion of the bar.
Crevice Corrosion
The presence of crevices, almost unavoidable in practical constructions and operations, makes stainless steel pipe more susceptable to corrosion in chloride enviroments. SAF 2507 is highly resistant to crevice corrosion. The critical crevice corrosion temperatures of SAF 2507 and several other high-performance stainless steel are shown above.
2507 Super Duplex Pipe
General Properties
Application
Standards
Chemical Composition
Resistance to Corrosion
Physical Properties
Mechanical Properties
Welding
Processing
ASTM A789/A789M
ASTM A 790/A 790M
Duplex Stainless Steel Pipe
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2507 S32750 1.4410 Duplex Stainless Steel Tube Pipe
Super-Duplex Stainless Steels and their characteristics
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