The low-alloy steel 09CrCuSb, also known as 09 Chromium Copper Antimony (ND steel), is specifically designed to resist sulfuric acid dew point corrosion. It is commonly used for seamless steel tubes, plates, forgings, and specialized welding materials.
The material is produced through ultra-high power electric furnace smelting, followed by secondary refining and vacuum degassing, ensuring high purity and uniform composition.
During the corrosion process, ND steel naturally develops a compact passivation layer enriched with chromium (Cr), copper (Cu), antimony (Sb), and titanium (Ti). This dense protective film provides excellent resistance to sulfuric acid condensation corrosion, giving the steel its remarkable durability and longevity.
As a low-alloy structural steel, ND steel offers superior mechanical strength and corrosion resistance compared with other steels such as mild steel, weathering steel (Corten), and Japanese grade CR1A.
Research has shown that ND steel forms a multi-layered, fine-grained passive film that contains significantly higher concentrations of Cr, Cu, Sb, and Ti than the base metal. This film enhances its protection capability under sulfur-rich conditions.
Experimental data indicate that in 70°C, 50% sulfuric acid solution, ND steel demonstrates 10 times the corrosion resistance of 20G mild steel, 3 times that of 304 stainless steel, and 1.5 times that of CR1A steel.
Chemical Composition
|
Grade |
Chemical Composition(%) |
|||||||
|
C |
Si |
Mn |
Cr |
Cu |
Sb |
P |
S |
|
|
09CrCusb |
≤0.10 |
0.20-0.40 |
0.35-0.65 |
0.70-1.20 |
0.25-0.45 |
≤0.10 |
≤0.10 |
≤0.10 |
Mechanical Properties
|
Grade |
Tenslle Strength(MPa) |
Yield Strength(MPa) |
Elongation(%) |
|
09CrCuSb |
390-550 |
≥245 |
≥25 |
Applications
09CrCuSb (ND steel) tubes and plates are widely used in power plants, refineries, and chemical industries to manufacture economizers, air preheaters, heat exchangers, and evaporators operating in high-sulfur flue gas environments, effectively preventing acidic condensate corrosion.
