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Is Inconel® 625 the same as Nickel 625?

The answer, not surprisingly, is yes and no. The chemistry, mechanical properties, and range of uses are within the same standards of quality, but Inconel® is a trademark that can only be used by one mill-Special Metals Corporation.

There's still some confusion among buyers, engineers, and machinists when it comes to superalloy grades. Why does the print say Inconel® 600 and the mill test reports refer to it as Nickel 600 or "ATI"® 600? Can one be substituted for the other? The answer to this is a definite yes. ASTM and AMS specifications guide the manufacturing of these high performance alloys. Reputable mills make absolute sure that the material they produce meets these strict standards. What's important in the name is not what comes before the alloy number, but the alloy number itself.


Why the Names?

Most of the high temp alloys were formulated after 1940 to support the high demands of aerospace engines. Jets needed to become more powerful, reliable, and durable. This required machined metal parts that surpassed the current technology. The nickel superalloys were developed to stand up to high pressure, highly corrosive, and high kinetic energy uses. The mills that developed these alloys trademarked them when granted their patents. Those trademarked names are still commonly used today, even though the patents have long expired.

Confusion and concessions

Your print might still say Inconel® and not Nickel. Airplanes last a long time. The end user can be slow to change the language used to purchase accepted components. Alloys can be referred to by the old trademarks out of habit.

All that can cause a problem, especially in Department of Defense contracts. The DOD contractor will often have to get a customer concession on the alloy name. For example, Inconel® 625, by that trademark, is not available in the metal distribution network. The name is currently owned by Special Metals Corporation, and they will only produce the alloy as a mill run quantity of 2000 lbs minimum. If you need less than that, like most machine shops we deal with do, you have to buy from a metal distribution center. We may or may not buy the product from Special Metals. More often than not material comes from a mill like Allegheny or Allvac. The same holds true for the Hastelloy® trademarks owned by Haynes International.

End Results

Vincent, and most other distributors, quote to generic names like "Nickel 400" instead of "Monel® 400", or "Alloy C-276" instead of "Hastelloy® C-276". We do this because the patents are no longer in effect on these high performance nickel alloys. We might be stocking nickel alloy rod made by any one of the high quality, tightly controlled DFARS-compliant mills that roll equally good product.

What really matters is that the material in the supply chain, the material that goes into products that have a huge impact on all our lives, are made to the highest standards of quality. And that they are mill tested and certified to accepted internationally recognized specifications.

All Trademarks are held by their respective owners