Material : Cobalt

United Titanium manufactures fasteners from cobalt-based multiphase alloys.  Fasteners made from these alloys offer excellent strength and toughness characteristics.  These alloys are designed for use in corrosive applications such as seawater, petrochemicals, aerospace and medical prosthetics and implants.


UT35N is a vacuum induction, vacuum arc remelted cobalt-based alloy that offers an unusually favorable combination of high strength and corrosion resistance. The nominal composition ofthis alloy is 35% Co, 35% Ni, 20% Cr, and 10% Mo.

In the annealed condition UT35N has a tensile and yield strengths of 135 ksi and 60 ksi, respectively. However, when properly work strengthened and age hardened, this alloy can attain an ultimate tensile strength ofover 300 ksi.

It is critical to recognize that the strength-imparting hexagonal-close-packed phase can only be achieved through deformation. Therefore, age-hardening of annealed material will not yield these high strengths. The proper combination of cold-work and aging of UT35N produces strength levels consistent with that ofthe high¬strength, low-alloy steels but offers superb ductility, toughness, and corrosion resistance as well. These attractive characteristics make alloy UT35N a terrific candidate for high performance fasteners, high strength wire, medical prostheses, and marine and aerospace components.

Due to the difficulty ofmachining in the age-hardened condition, the manufacture ofcomponents in UT35N most often uses AMS 5844 material (solution treated and work strengthened). Once machining and forming operations are complete, the component is age hardened to achieve AMS 5845 properties.

UT35N Mechanical Properties

Common Name  Minimum Values
UTS (ksi) YS (ksi) EI (%) Ra(%)
UT35N 260 230 8 35

UT35N Material Specifications

AMS 5844 Solution Treated and Cold Drawn Rod (Bar) AMS 5845 Solution Treated, Cold Drawn, and Age Hardened Rod (Bar)


Conventional UT159 is an alloy with a unique combination of ultra-high strength, ductility, and corrosion resistance capable of 260 ksi or more. It is from this alloy that the new superalloy UT98T (also known as UT159 Modified) evolved for meeting the ever-changing requirements for critical naval marine fasteners

UT98T meets the demand for a fastener material with superior fracture toughness to go with high strength and good ductility. While the chemistry of UT98T is identical to that of UT159, superior fracture toughness was achieved while retaining exceptional strength by modifying the cold work and age hardening parameters

A key component of the success of this alloy comes from transfonning a part of the matrix from one crystal structure to another, thus creating a multiple-phase structure. For this reason UT98T is a terrific candidate for the production of large diameter fasteners since the cold-work and age hardening parameters allow for consistent properties throughout the cross-section of the fastener.

UT98T Mechanical Properties

Common Name  Minimum Values
UTS (ksi) YS (ksi) EI (%) Ra(%)
UT159* 265 255 8 35
UT98T* 200 160 15 40

*Work Strengthened and Age Hardened

UT98T Material Specifications

AMS 5919 Solution Treated and Work Strengthened Bar AMS5920 Solution Treated, Work-Strengthened, and Age Hardened Bar