H.C. Starck offers NRC® niobium metal produced from electron beam melted ingots. Grain Stabilized Niobium (GSNb) is made by EB and VAR melting. Both materials are malleable, weldable, machineable and formable. GSNb is used in applications where a consistently finer grain size is required.

GSNb is a patent pending single-phase micro-alloy that has a grain size of approximately 2 ASTM numbers finer than standard commercial grade niobium.

Niobium is used in the manufacture of products for diverse applications.

  • Synthetic diamonds
  • Sputtering targets for fiber optic applications or architectural glass
  • Nickel based superalloys; and alloyed with titanium or tin
  • Superconductors
  • Nuclear reactors it has low thermal neutron cross section and superior  corrosion resistance
  • High temperature vacuum furnaces, where it is an excellent getter
  • Sodium vapor lamps, where it is resistant to attack by the molten alkali

Niobium Sheet and Plate

Niobium sheet and plate are supplied with a cold-rolled and chemically-cleaned surface. Because of their strength and workability, very thin sheets of niobium can be clad to other surfaces, providing superior corrosion protection and cost effectiveness.

Depending on your specifications and needs, all of our niobium sheet and plate are visually inspected for slivers, laminations, excessive roll marks and handling scratches.

Niobium Rod

Niobium rod is worked cold from ingot to final diameter. Forging, rolling, swaging, and drawing are used singularly or in combination to reach the desired size. Proprietary techniques have been developed by H.C. Starck to overcome the metal's extremely high-galling tendencies.

Rod is generally supplied with a forged surface above 1-3/8" diameter, and a swaged or drawn finish in smaller diameters. Rod, preferably un-annealed, may be centerless ground to improve diameter tolerances. The minimum diameter for centerless grinding is .125". Rod to a maximum of 1/4" and wire may be supplied in coils or straightened and cut to length.

Corrosion Resistance

The corrosion resistance of GSNb is identical to that of commercial grade niobium and can be used in all applications where commercial grade niobium is used. Like tantalum, GSNb is resistant to most acids with the exception of hydrofluoric, however it is not as resistant as tantalum to strong acids at high temperature. It should not be used with strong bases (alkalis).


Type I (R04200) – Reactor Grade 0.1% Ta Max.
Type II (R04210) – Commercial Grade 0.2% Ta Max.
GSNb – Per H.C. Starck Internal Specification

Metallurgical Characteristics

Material is single-phase niobium. Stress relieve at 650°C, Re-crystallize at 950°C.


Foil0.001” to 0.006” thick by widths up to 12” wide
0.006” to 0.1875” thick by widths up to 40” wide
0.1875” to 1” thick in common widths
Welded Tubing
0.015” to 0.035”wall x ½” to 2” diameter

Plate, Rod, Wire, Bar and customer specified specialty sizes of all materials:

Physical Properties of Niobium

Atomic Number41
Atomic Weight
8.57 gm/cc (0.31 lbs/in3)
Melting Point
Coefficient of Expansion 
(20° – 100°C) 7.1 X 10-6/K
Specific Heat (27°C) 
0.065 cal/gm/°C
Thermal Conductivity 
54 W/m K
Electrical Resistivity (0° - 100°C)14.5 microhm-cm
Crystal Structure

Mechanical Properties of GSNb (annealed):

GSNb meets the mechanical properties requirements of ASTM B393 Type 2 Commercial Grade Niobium (UNS R04210)
Tensile Strength   18,000 psi (125 MPa) minimum
Yield Strength   
10,500 psi (73 MPa) minimum
20 % minimum (above 0.004” thick)
15 % minimum (0.002 to 0.0039” thick)

Additional information not included in ASTM B363

Hardness (Typical): HV 10
Grain Size (ASTM): 6 or finer (45 ums) for thicknesses < 0.010”

Olsen Cup Testing is available on request for thinner gauges.
GSNb has similar values to Commercial Grade niobium.
Typical Olsen Cup depth values for 0.005 to 0.010” thick GSNb are 0.240” (6.1mm).


Machinability: While challenging, GSNb can be machined using high rake angle tools, slow feeds and speeds, and water-soluble oils.

Weldability: GSNb can be resistance welded to itself and other metals such as tantalum, nickel, platinum, titanium and niobium. It can be welded using GTAW (TIG) using proper shielding and cleanliness techniques. It can also be Electron Beam (EB) welded.

Heat Treatment: GSNb will recrystallize at temperatures above about 1650 °F (900°C) (Heat treat in vacuum only).

Typical Applications

Sheet/Strip/Foil for forming applications such as crucibles, cups, and formed parts. Any application that can use commercial grade niobium but requires improved forming and surface finish.

Niobium and Niobium Alloy Products:

Refer to Product Data Sheets for Niobium for sizes:

PD-7034 Niobium (COLUMBIUM)

PD-7038 Grain Stablizied Niobium (GSNb)