Alloy C-276 (UNS N10276)

Description

Alloy C-276 is a nickel-molybdenum-chromium-iron-tungsten alloy which is among the most corrosion resistant of alloys currently available. The C-276 alloy is widely used in the severest environments encountered in the chemical and petrochemical processing, flue gas desulfurization, pulp and paper and other specialized fields. Design of the alloy allows a high level of corrosion resistance to be retained even in the welded condition.

Alloy C-276 also has good high temperature strength and moderate oxidation resistance although the alloy will eventually form embrittling high temperature precipitates.  This alloy is exceptionally resistant to crevice corrosion and stress corrosion cracking and to chemical attack in both highly oxidizing to moderately reducing conditions.  Alloy 625 is virtually immune to corrosion in marine environments and is used extensively in the hot section of jet engines and in high temperature corrosive environments in the chemical processing industry. The alloy has outstanding resistance to creep and stress rupture up to 1200ºF (649˚C), and oxidation and scaling resistance up to 2000ºF (1093˚C).

The alloy is readily fabricated by welding using techniques similar to those used for austenitic stainless steels and other nickel base alloys. Precautions are advisable during fabrication because raising the low carbon and silicon contents of the material may adversely affect the corrosion resistance.

Chemical Composition

Chemical Composition (wt%) limits as specified in ASTM B574*

Carbon 0.010 Silicon 0.08
Chromium 14.5-16.5 Cobalt 2.5
Iron 4.0-7.0 Vanadium 0.35
Molybdenum 15.0-17.0 Phosphorus 0.04
Tungsten 3.0-4.5 Sulfur 0.03
Manganese 1.0    

*Maximum, unless range is indicated

Physical Properties

Physical properties for Alloy C-276

Density, lb/in3 0.321
Modulus of Elasticity, psi 29.8 x 106
Coefficient of Thermal Expansion, 68-212˚F, /˚F 6.2 x 10-6
Thermal Conductivity, Btu/ft hr ˚F 5.9
Specific Heat, Btu/lb ˚F 0.10
Electrical Resistivity, Microhm-in 51.2

Mechanical Properties

Mechanical property requirements as specified for annealed product in ASTM B 574

Yield Strength, min. (ksi) 41
Tensile Strength, min. (ksi) 100
Elongation, min. (%) 40

Standards

Typical standards for Alloy C-276

ASTM B574
ASME SB574