Alloy 20

Alloy 20 is a nickel–chromium–molybdenum stainless steel alloy developed for applications involving sulfuric acid. Its corrosion resistance also finds other uses in the chemical, food, pharmaceutical, power generation, and plastics industries. Alloy 20 resists pitting and chloride ion corrosion and its copper content protects it from sulfuric acid. Alloy 20 is not a stainless steel but a nickel alloy (ASTM). Alloy 20 is often chosen to solve stress corrosion cracking problems, which may occur with 316L stainless.

It is also known as Carpenter 20. Cast versions are designated CN7M.

Composition

• Nickel, 32.5–35%
• Chromium, 19–21%
• Carbon, 0.06% maximum
• Copper, 3–4%
• Molybdenum, 2–3%
• Manganese, 2% maximum
• Silicon, 1% maximum
• Niobium, (8.0 X C), 1% maximum
• Iron, 31–44% (balance)

Other names^[1]

• UNS N08020
• DIN 2.4660.
• CN7M

• Carpenter 20 CB 3^TM
• AL 20^TM
• Carlson Alloy C20^TM
• Nickelvac 23^TM
• Nicrofer 3620 Nb^TM

Specifications

ASTM B729, B464, B366, B463, B473, B462^[1]

ASME SB729, SB464, SB366, SB473, SB462

ANSI / ASTM A555-79^[2]

EN 2.4660^[3]

UNS N08020^[3]

Werkstoff 2.4660^[3]

References