MP35N Springs

MP35N is a non-magnetic Cobalt-Nickel-Chromium-Molybdenum alloy having an excellent combination of very high strength, excellent corrosion resistance, and high fatigue strength.

Technical Specification MP35N
Nominal Composition

Ni:33.0 - 37.0
Cr: 19.0 - 21.0

Co: balance

Mo: 9.0 - 10.5


0.304 lb./in3, (8.42 g/cm3)

Modulus of Elasticity (E)

At 70°F (20°C):33.8 x 10 3 ksi

Modulus of Rigidity (G)

At 70°F (20°C):12.1 x 103 ksi

Coefficient of Expansion

8.2 µin/in.-°F (70°F to 600°F)

Electrical Resistivity

40.6 µΩ.in, (103µΩ.cm)

Thermal Conductivity

78 Btu-in/ft2hr-°F

Min Size

0.005 in (0.127 mm)

Max Temp

315oC (600oF)

Uses of MP35N

MP35N is recommended for applications where a combination of high strength and high corrosion resistance are required. Precipitation treatment is required to develop full spring properties.  Primary examples of use in Oil Field and Downhole springs.  Used when failure from corrosion and sour gas are issues.  This material allows better performance over Inconel X750 in such applications due to improved strength and ductility.