Overview
CK20 is an austenitic stainless steel casting alloy defined by ASTM A351/A351M, primarily intended for high-temperature, pressure-containing components such as reformer tubes, manifolds, and heat exchanger parts. With a nominal composition of 25% chromium and 20% nickel, CK20 offers excellent resistance to oxidation, carburization, and sulfidation in elevated-temperature service environments. Its stable austenitic microstructure ensures good creep resistance and structural integrity under long-term thermal exposure, making it a preferred material in the petrochemical, refining, and heat treatment industries. CK20 is widely used where both high-temperature strength and corrosion resistance are critical for reliable performance.
Chemical Composition
Carbon
Manganese
1.50% Max
Silicon
1.75% Max
Phosphorus
0.04% Max
Sulfur
0.04% Max
Chromium
23.00 - 27.00%
Nickel
19.00 - 22.00%
Molybdenum
0.50% Max
Mechanical Properties
Yield Strength
28 ksi Min
Tensile Strength
65 ksi Min
Elongation at 2 in
30% Min
Resources
ASTM Standard