Melt Practice

This superalloy is initially melted using Vacuum Induction Melting (VIM) techniques. This is followed by an Electro Slag Remelt (ESR) to remove some impurities. This practice may be followed by Vacuum Arc Remelting (VAR). The triple-melt practice is thought to give best overall performance for this alloy.

  ASTM F562
Carbon 0.025
Manganese 0.15
Silicon 0.15
Phosphorus 0.015
Sulfur 0.01
Chromium 19-21
Nickel 33-37
Molybdenum 9-10.5
Cobalt Balance
Titanium 1
Iron 1
Boron 0.015

Physical Properties
Density 0.304 lbs/in3
Modulus Of Elasticity 33.76-34.05 psi x 106
Electrical Resistivity 1033 µohms-mm
Thermal Conductivity 11.2 W/mK (100°C)

Thermal Treatment

A reducing atmosphere is preferred for thermal treatment but inert gas can be used. MP35N will fully anneal at 1010-1177°C in just a few minutes. For optimum mechanical properties, cold worked MP35N should be aged at 538-593°C for four hours.


MP35N is an excellent combination of strength and corrosion resistance. Typically used in the cold-worked condition, tensile strengths are typically comparable to 304. End uses in the medical field are: pacing leads, stylets, catheters and orthopaedic cables.

Mechanical Properties
%CW U.T.S. (psi) % Elongation
(10" gauge length)
0% 152,000 50%
20% 201,000 7%
37% 253,000 3%
50% 285,000 2.5%
60% 303,000 3.2%
68% 319,000 3.0%
75% 329,000 3.1%
80% 332,000 3.3%
84% 339,000 3.2%
90% 345,000 3.4%
93% 346,000 2.2%
95% 362.000 2.8%

Values are typical and may not represent all diameters. Test method will affect results.

Surface Condition

Cobalt based alloys develop a highly polished appearance as they are drawn to fine diameters. Surface roughness can be less than 5 RMS when processed using SCND* dies and measured with a profilometer.

Diameters over 0.040" will not have as smooth a finish because of polycrystaline dies. Diameters over 0.100" will have an even rougher surface because they are drawn with carbide dies. Additional finish treatments can enhance the surface of the wire.

*SCND means single crystal natural diamond.