Overview
When selecting materials, you've likely come across a variety of designations, such as Monel 400, UNS N04400, and W.Nr. 2.4360. Perhaps you're wondering why the same grade has so many different designations. It can be confusing.
In this article, we'll explain the specifications of each grade and provide a detailed nickel alloy grade comparison table.
What is Grade?
The alloys we commonly encounter are made by fusing different metallic elements. These elements, combined in varying proportions, form various grades. In other words, different grades have different chemical compositions. These differences in chemical composition lead to varying properties, making them suitable for different applications.
In the field of nickel alloys, alloys with similar compositions are generally grouped together into a broad category. For example, Monel alloy refers to a nickel-copper alloy, primarily nickel and copper. Inconel, on the other hand, is primarily a nickel-chromium alloy. Incoloy is primarily a nickel-chromium-iron alloy. Hastelloy is a nickel-chromium-molybdenum alloy.
Within this broad category of alloys, there are many specific grades. For example, Monel 400 refers to an alloy with a nickel content greater than 63% and a copper content of 28-34%. However, the same grade can sometimes be referred to by different names. For example, Monel 400 is also known as UNS N04400 or W.Nr. 2.4360 (in practice, the UNS and W.Nr. are omitted). Below, we will introduce these two specifications.
What is UNS?
UNS stands for Unified Numbering System. It is an alloy designation system jointly developed by ASTM and SAE. It was developed to resolve the confusion surrounding alloy grade designations, providing a single, standardized designation for each metal.
UNS applies to all metal materials. Its standard designation is as follows:
UNS designates the use of the Unified Numbering System. N designates the alloy type as nickel alloy. 04400 designates the specific grade.
UNS is recognized by all major standards. ASTM, ASME, and SAE all use the UNS designation for different grades. This eliminates ambiguity caused by different grade names and standardizes the entire quality control process.
What is W.Nr.?
W.Nr. (German: Werkstoffnummer) is a metal material numbering system developed by DIN. It is also widely adopted by EN (European Union Standards). W.Nr. has a significant influence in Europe. Its standard notation is:
The digits before the “.” indicate the material's properties. For example, 1 represents steel, and 2 represents an alloy. The four digits following the “.” indicate the specific grade of the material. In actual procurement, W.Nr. is relatively rarely mentioned.
Specifications of Filler Metal and Welding Electrode
The specifications for filler metal and welding electrode are more specialized. They require reference to AWS A5.14 and AWS A5.11, respectively. These standards specify the specifications for different grades. The standard designation for filler metal is:
The standard designation for welding electrode is:
Where AWS A5.14/A5.11 indicates the referenced standard. ER stands for filler metal, and E stands for welding electrode. The following letters represent the primary element in the grade. The "-" followed by a number distinguishes materials of the same type.
It is important to note that the composition of some grades of filler metal and welding electrode differs from the standard composition. For example, the standard Monel 400 has a maximum silicon content of 0.5%. Monel 400 filler metal has a maximum silicon content of 1.25%, while Monel 400 welding electrode has a maximum silicon content of 1.5%. Besides silicon, they also have other compositional differences. Therefore, their UNS numbers are also different, namely: UNS N04400, UNS N04060 and UNS W84190.
Nickel Alloy Grade Comparison Table
The following table summarizes the specifications of different grades:
| Grade | UNS | W.Nr. | AWS A5.14 | UNS | AWS A5.11 | UNS |
|---|---|---|---|---|---|---|
| Monel 400 | N04400 | 2.4360 | ERNiCu-7 | N04060 | ENiCu-7 | W84190 |
| Monel 401 | N04401 | / | / | / | / | / |
| Monel 404 | N04404 | 2.4867 | / | / | / | / |
| Monel R-405 | N04405 | / | / | / | / | / |
| Monel K-500 | N05500 | 2.4375 | ERNiCu-8 | N05504 | / | / |
| Inconel 600 | N06600 | 2.4816 | ERNiCr-3 | N06082 | ENiCrFe-3 | W86182 |
| Inconel 601 | N06601 | 2.4851 | ERNiCrFe-11 | N06601 | / | / |
| Inconel 602CA | N06025 | 2.4633 | ERNiCrFe-12 | N06025 | ENiCrFe-12 | W86025 |
| Inconel 617 | N06617 | 2.4663a | ERNiCrCoMo-1 | N06617 | ENiCrCoMo-1 | W86117 |
| Inconel 625 | N06625 | 2.4856 | ERNiCrMo-3 | N06625 | ENiCrMo-3 | W86112 |
| Inconel 625LCF | N06626 | 2.4856 | / | / | / | / |
| Inconel 686 | N06686 | 2.4606 | ERNiCrMo-14 | N06686 | ENiCrMo-14 | W86026 |
| Inconel 690 | N06690 | 2.4642 | ERNiCr-7 | N06073 | ENiCrFe-7 | W86152 |
| Inconel 693 | N06693 | / | ERNiCrFeAl-1 | N06693 | / | / |
| Inconel 706 | N09706 | / | / | / | / | / |
| Inconel 718 | N07718 | 2.4668 | ERNiFeCr-2 | N07718 | / | / |
| Inconel 718SPF | N07719 | / | / | / | / | / |
| Inconel 725 | N07725 | / | ERNiCrMo-15 | N07725 | / | / |
| Inconel 740H | N07740 | / | ERNiCrCo-1 | N07740 | / | / |
| Inconel X-750 | N07750 | 2.4669 | / | / | / | / |
| Inconel 751 | N07751 | / | / | / | / | / |
| Inconel MA754 | N07754 | / | / | / | / | / |
| Inconel 783 | R30783 | / | / | / | / | / |
| Incoloy 800 | N08800 | 1.4876 | / | / | / | / |
| Incoloy 800H | N08810 | 1.4958 | / | / | / | / |
| Incoloy 800HT | N08811 | / | / | / | / | / |
| Incoloy 803 | S35045 | / | / | / | / | / |
| Incoloy 825 | N08825 | 2.4858 | ERNiFeCr-1 | N08065 | / | / |
| Incoloy 864 | S35135 | / | / | / | / | / |
| Incoloy 890 | N08890 | / | / | / | / | / |
| Incoloy 903 | N19903 | / | / | / | / | / |
| Incoloy 907 | N19907 | / | / | / | / | / |
| Incoloy 908 | N09908 | / | / | / | / | / |
| Incoloy 909 | N19909 | / | / | / | / | / |
| Incoloy 925 | N09925 | / | / | / | / | / |
| Incoloy 926 | N08926 | 1.4529 | / | / | / | / |
| Incoloy 945 | N09945 | / | / | / | / | / |
| Incoloy 945X | N09946 | / | ERNiFeCr-3 | N09946 | / | / |
| Incoloy MA956 | S67956 | / | / | / | / | / |
| Incoloy A-286 | S66286 | 1.4980 | / | / | / | / |
| Incoloy 20 | N08020 | 2.4660 | / | / | / | / |
| Incoloy 28 | N08028 | 1.4563 | / | / | / | / |
| Incoloy DS | 1.4862 | 1.4862 | / | / | / | / |
| Incoloy 330 | N08330 | 1.4886 | / | / | / | / |
| Incoloy 25-6HN | N08367 | / | / | / | / | / |
| Incoloy 27-7MO | S31277 | / | / | / | / | / |
| Hastelloy B | N10001 | / | ERNiMo-1 | N10001 | ENiMo-1 | W80001 |
| Hastelloy B-2 | N10665 | 2.4617 | ERNiMo-7 | N10665 | ENiMo-7 | W80665 |
| Hastelloy B-3 | N10675 | 2.4600 | ERNiMo-10 | N10675 | ENiMo-10 | W80675 |
| Hastelloy C-4 | N06455 | 2.4610 | ERNiCrMo-7 | N06455 | ENiCrMo-7 | W86455 |
| Hastelloy C-22 | N06022 | 2.4602 | ERNiCrMo-10 | N06022 | ENiCrMo-10 | W86022 |
| Hastelloy C-22HS | N07022 | / | / | / | / | / |
| Hastelloy C-276 | N10276 | 2.4819 | ERNiCrMo-4 | N10276 | ENiCrMo-4 | W80276 |
| Hastelloy C-2000 | N06200 | 2.4675 | ERNiCrMo-17 | N06200 | ENiCrMo-17 | W86200 |
| Hastelloy G-3 | N06985 | / | ERNiCrMo-9 | N06985 | ENiCrMo-9 | W86985 |
| Hastelloy G-30 | N06030 | 2.4603 | ERNiCrMo-11 | N06030 | ENiCrMo-11 | W86030 |
| Hastelloy G-35 | N06035 | / | ERNiCrMo-22 | N06035 | ENiCrMo-22 | W86035 |
| Hastelloy N | N10003 | / | / | / | / | / |
| Hastelloy S | N06635 | / | / | / | / | / |
| Hastelloy W | N10004 | / | ERNiMo-3 | N10004 | ENiMo-3 | W80004 |
| Hastelloy X | N06002 | 2.4665 | ERNiCrMo-2 | N06002 | ENiCrMo-2 | W86002 |
FAQ
Are the different specifications simply different names?
For most materials, the different specifications are simply different names; they all represent the same material. However, for filler metal and welding electrodes, there are sometimes subtle compositional differences.
Which of these specifications is most commonly used?
Generally speaking, names like Monel 400 and Inconel 600 are the most common because they are easier to pronounce. UNS is the second most common specification, and most standards use this type of specification.
Further Reading
Conclusion
Alloys are classified into different grades based on their chemical composition. Each grade corresponds to a variety of notations, known as specifications. UNS is a commonly used specification in the United States, while W.Nr. is more common in Europe. The AWS specification primarily applies to filler metal and welding electrode.
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