> Niobium


BIMO is one of the leading producers and suppliers of Niobium products and niobium components. Our niobium is serving the full range of applications: special industrial machinery, sodium vapor lamps, superconductor materials, beams and girders in buildings and offshore drilling towers, oil and gas pipelines, railroad equipment, and automobiles.


Our standard inventory and production sizes are as follows.

  • Niobium Rods
  • Niobium Wires
  • Niobium Tubes
  • Niobium Flanges
  • Niobium Pipes
  • Niobium Fasteners
  • Niobium Sheets
  • Niobium Plates

Custom sizes and parts can easily be made upon request.




Niobium Properties



Tensile strength (at room temperature)

275 MPa

40 ksi

Modulus of elasticity

105 GPa

15250 ksi

Shear modulus

38 GPa

5511 ksi

Poissons Ratio



Hardness, Brinell



Hardness, Vickers



Hardness, Mohs





8.57 g/cc

Melting Point:

2750 K, 2468 degrees C, 4490 degrees F

Boiling Point:

5017K, 4927 degrees C, 8571 degrees F

Coefficient of Thermal Expansion (20 degrees C):

7.1 x 10-6/degrees C

Electrical Resistivity (20 degrees C):

15 microhms-cm

Electrical Conductivity:

13.2% IACS

Specific Heat:

.126 cal/g/degrees C

Thermal Conductivity:

.523 cal/cm2/cm degrees C/sec



Machining Niobium


Thanks to its high level of ductility, niobium is very suitable for forming processes such as bending, stamping, pressing or deep-drawing. To prevent cold welding, it is preferable to use steel or hard metal tools. It is very difficult to use cutting processes with niobium. The chips do not break cleanly. We therefore recommend using tools equipped with chip formers. Niobium offers excellent weldability compared to tungsten and molybdenum.


The machining characteristics of niobium and its common alloys are similar to those of 316 stainless steel, and in lathe turning they behave much like soft copper. Fine chips and grinding dust of niobium and niobium-based alloys may burn and sustain combustion. Special attention needs to be paid to tool design and lubricant use. All of the normal machining techniques can be used for Niobium. The use of high speed tooling with adequate lubrication and cooling with soluble oil following the parameters given here is recommended.

Although carbide tools can be used, the tendency to gall is more pronounced with them with high speed steel. In turning, the metal should be removed in a shearing action and the chip allowed to slide off the tool surface. When build-up of the chip occurs, the resulting pressure breaks the cutting edge of the tool.

The machining recommendations shown in the accompanying table generally give satisfactory results. The minimum surface speed of 80 feet per minute is important. Slower speeds will cause the metal to tear, particularly annealed stock. Normally, unannealed metal is preferred for lathe operations.

The forming characteristics of niobium and niobium alloys should be similar to copper and some mild steels. Niobium sheet metal can be formed easily without special working techniques. There are two unusual features that must be considered when working with niobium and its alloys. First, no appreciable softening occurs below 400°C (752°F), because of its high melting point. Also, sheathing protection is not practical, since the sheathing material is likely to be softer than the niobium. Niobium’s cold working properties are excellent. Annealing is necessary after the surface has been worked 90%, with heat treatment at 1200°C (2192°F) for one hour causing complete recrystallization of material cold worked over 50%. The annealing must be performed in an inert gas, or preferably, in a high vacuum.


Tooling Recommendations for Machining Niobium

Approach angles:

15-20 degrees

Side Rake:

30-35 degrees

Side and End Clearances:

5 degrees

Plan Relief Angle:

15-20 degrees

Nose Radius:


Cutting Speed:

60-80 feet / minute with high speed steel; 250-300 feet / minute with carbide tools


Feed, Roughing .008″-.012″ / revolution

Depth of cut:




Drilling Niobium

Drilling niobium and its alloys is accomplished using standard high-speed drills. It is necessary to check the peripheral lands of the drill often for excessive wear; this will prevent drilling undersized holes.


Grinding Niobium

Grinding niobium is difficult. Most grinding wheels have a tendency to load, and silicon carbide wheels such as Carborundum 120-T (for rough grinding) and 120-R or 150-R (for finishing) should be used. An adequate supply of cooling water is desirable.


Threading Niobium

Standard techniques for threading can be used when enough lubricant is available to reduce the galling tendency and consequent tearing of the metal from the surfaces. In threading larger diameters, it is better to cut the threads on a lathe rather than with a threading die. When dies or taps are used, they must be kept free of chips and cleaned often.


Sawing Niobium

No special considerations are necessary when sawing niobium and its alloys. High-speed steel blades can be used with power hacksaws, band saws, and circular saws.


Blanking and Punching Niobium

Dies and punches made of steels usually used for this purpose are satisfactory for niobium. A 6% clearance between the punch and the die is recommended. Light oils or similar lubricants should be used to prevent scoring the dies.


Form Stamping Niobium

Beryllium copper, aluminum bronzes, and steel may be used for tools. The techniques used can be the same as used for stamping steel. The tools should be polished to reduce the tendency to gall as much as possible. Light oils or similar lubricants should also be used, again to reduce the chances of galling.


Deep Drawing Niobium

Deep drawing of annealed niobium can be accomplished without much difficulty. Tool materials such as steel, aluminum bronzes, and beryllium copper can all be used for drawing operations. Single draws can be made if the depth of the draw does not exceed the diameter of the blank can be accomplished. Intermediate annealing in a vacuum may be desirable with multiple draws. Sulfonated tallow and Johnson’s 150 drawing wax can be used as lubricants.


Spinning Niobium

Normal techniques of metal spinning may be applied successfully to niobium, with minor modifications. The metal should be worked in small steps or stages with long sweeping strokes using light pressure rather than a few heavy strokes. Wooden formers may be used for rough spinning, but a brass or bronze former is essential for finishing, because the metal is soft and takes up the contour of the former. Yellow soap, or tallow, is suitable for lubricating the material, which must be cold worked continually. The peripheral speed of the work piece should be about 500 feet per minute. When spinning, niobium is prone to thinning and care must be taken to avoid this. The tool should be worked in many long sweeping strokes using a light pressure rather than a few heavy strokes.


Welding Niobium

As already stated, niobium is a very reactive metal. It reacts with all of the common gases. The metal also reacts with surface contaminants such as oil, grease, residues from degreasing solutions, and residues from cleaning fluids such as acetone. It is for these reasons the surfaces of metal to be welded, either by fusion or resistance welding must be absolutely clean before welding.

An acid etch in a solution of 45 parts nitric acid, 1 part hydroflouric acid, and the rest water at ambient temperatures or up to 65 degrees C (150 degrees F) is acceptable. The amount of hydrofluoric acid may be increased if a more severe etching action is needed. The metal should be thoroughly rinsed after etching, preferably in distilled or deionized water.


Resistance Welding Niobium

Resistance welding of niobium to niobium and certain other metals can be done with conventional equipment and techniques. Because of it’s high melting point and relatively low electrical resistance, niobium requires a high power input to obtain a sound weld. Weld duration should be kept as short as possible, preferably 1-10 seconds (60Hz) to prevent excessive heating of the weld area. If at all possible, the work should be flooded with water. In seam resistance welding, the work actually should be submerged in water, to exclude both air from the heat affected zone and to cool the metal as rapidly as possible.

RWMA Class 2 welding electrodes are recommended and should have water cooling. Any copper pick up on the niobium could be easily removed by pickling in nitric acid, which will not attack niobium. As already emphasized, the parts to be welded must be thoroughly cleaned before welding. After the parts have been cleaned, they should be handled with lint-free cotton gloves so that body oils will not contaminate the surfaces.


Fusion Welding Niobium

Strong, ductile fusion welds can be made with niobium using TIG welding. Because of the weld’s reactivity with air, certain modifications to the TIG method must be made.

The best approach is to weld in a chamber, using argon or a mixture of argon and helium. If chamber welding is not practical or not available, welding in a normal atmosphere can be done with proper fixturing to provide an inert gas atmosphere not only for the molten zone, but also for the heat affected zone. Trailing shields are necessary to protect the fusion zone during cooling and the metal must not be exposed to air until the temperature has dropped to 260 degrees C (500 degrees F) or lower. The back side of the weld zone must also be protected with inert gas shield during both the welding and cooling cycles.

Normal sheet with a thickness of .050″ or less can be welded without using a filler rod. Heavier sheet often requires the use of filler rod. Bare rod should be used. Use of coated rod or any flux is not good practice, since molten niobium reacts with all of the known fluxes. Cleanliness of the material to be welded as well as the filler rod is essential.

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