Posted by Eric von Spreckelsen on

 

When you call your local metal supplier and ask for a coil of tantalum sheet or a plate of niobium, do they ask you about your application? Do they ask you what type of machining you will be performing or if you’re drawing parts from this material? These are examples of important questions to ask.

If you’re a new customer to Admat, we always ask these questions. Not to be nosy or to take up your time. But, because tantalum and niobium are unique metals which can be manufactured in multiple fashions. After all tantalum and niobium are expensive and we don’t want to sell you something that will not work in your application. For example, a customer using material for stamped parts will want softer metal that is able to be drawn without the surface becoming grainy or tearing, while someone using the material for shielding may want the material stiffer. Some customers use the material for semiconductors and they want exceptional purity of 99.999% pure while others are lining a chemical tank and 98% pure is less expensive and ideal for their job.

We can supply material in multiple tempers, with “as rolled” surfaces, or conditioned surfaces. Admat’s extensive experience with these metals can help you decipher what your material requirements should be, in most cases, just by asking a few questions. Still it is always a good idea to get a basic understanding of the typical standards yourself.

There are so many different specifications of tantalum that one can easily become confused. It’s important to be educated regarding specifications and grades of tantalum and how they apply to the materials.

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ASTM specifications for tantalum and niobium are by far the most commonly used today. These specifications clearly lay out the chemical, mechanical, and physical requirements of the material. Because different diameters, thicknesses or widths may impact the mechanical properties or manufacturing tolerances, ASTM has charts that include a wide variety of sizes. If your material is outside the range on the charts, that particular property will not apply. In such a case it is best to speak with Admat to determine what requirements are possible.

As for chemistry, there are multiple alloys of tantalum and niobium, each with unique requirements. ASTM utilizes the UNS (Unified Numbering System) to differentiate. We have included a chart in this post which lists some of the more common metals and alloys.

In addition to ASTM specifications and which particular alloy, you must also consider the temper of the material. In other words, do you want the manufacturer to vacuum heat treat the material to relieve the stresses and reform the crystal structure of the material. Annealed material is most commonly ordered if you plan on forming the material in such a method as stamping, drawing or spinning, or if you are going to use the material as a sputtering target. However most commonly rods or bars are ordered as unannealed unless you plan on working (not machining) the material further. This would apply mostly to wire drawing.

The second most common series of specifications are managed by SAE International. These specifications most commonly apply to tantalum and niobium for aerospace applications. SAE specifications start with AMS and are very similar to the ASTM standards.

Many businesses have their own specifications for refractory metals. Admat would be happy to review your existing specs or help your engineers develop one to fit your process. Furthermore Admat has internal specifications for various end uses. For example if you are using the material to makes springs for drinking water chlorinators, Admat has a proprietary internal specification just for that material and end use.

Even if your business does not have your own standard, Admat will ensure you get the right material for the job.

Call our experts today and let them help you determine the right specification for your process.