DZR (Dezincification Resistant) and CW617N are brass alloys, but they differ significantly in their resistance to dezincification – a type of corrosion that can weaken brass components. CW617N is a standard brass alloy that is susceptible to dezincification, whereas DZR brass is specifically designed to resist this type of corrosion. This difference results from their composition and manufacturing processes, with DZR containing additives such as arsenic or nickel that help prevent dezincification.
CW617N
Composition:
Typically contains copper (57–59%), zinc (37–40%), and lead (1.5–2.5%).
Dezincification:
Highly susceptible to dezincification, especially in aggressive water environments.
Application:
The lead content may limit its use in potable water applications.
Machinability:
Good machinability due to the presence of lead.
DZR (Dezincification Resistant) Brass
Composition:
The composition may vary, but DZR brass generally has a higher copper content and a lower zinc content than CW617N. It also contains additives such as arsenic (up to 0.15%) or nickel (up to 0.3%) that prevent dezincification.
Dezincification:
Specifically designed to resist dezincification, making it suitable for applications where corrosion resistance is critical.
Applications:
Used in plumbing systems, water fittings, and other applications where exposure to water may lead to corrosion.
Manufacturing:
May be more expensive than CW617N due to specific alloying and manufacturing processes.
Main Differences
Resistance to Dezincification:
DZR is specifically engineered to resist dezincification, whereas CW617N is not.
Composition:
DZR brass has a different composition, often with lower zinc and higher copper content, and includes additives such as arsenic or nickel.
Application:
DZR is preferred in situations where corrosion is a concern, while CW617N is suitable for general applications where dezincification is not a primary factor.
Cost:
Due to specific manufacturing requirements, DZR brass may be more expensive.
Dezincification is a type of corrosion that affects brass – an alloy of copper and zinc. It occurs when zinc is selectively removed from the alloy, leaving behind a porous, copper-rich structure. This process weakens the brass and can lead to leaks, cracks, or even component failure.
What Is It?
Dezincification is a form of corrosion in which zinc is preferentially removed from brass.
It leaves behind a porous, copper-rich layer that is weaker than the original brass.
This process can occur in various environments but is especially common in plumbing and water systems.
How Does It Occur?
Zinc is more reactive than copper and is therefore more susceptible to corrosion under certain conditions. In the presence of water – particularly with high chloride or sulfate content, low alkalinity, or a pH around 8 – zinc can dissolve while copper remains. This may occur uniformly across the surface or locally, forming cavities or plugs.
Consequences of Dezincification:
Weakening of the brass component, which may lead to leaks, cracks, or breakage.
Reduced mechanical strength in the affected area.
A color change of the brass from yellow to pinkish or reddish.
Prevention of Dezincification:
Using brass alloys with lower zinc content (less than 15%).
Adding alloying elements such as tin, arsenic, or antimony.
Ensuring proper water chemistry and avoiding stagnant water or high chloride levels.
Using dezincification-resistant brass (DZR brass) in plumbing applications.
