Nickel and nickel alloys are widely used in various industrial applications due to their excellent mechanical properties (high strength, toughness, oxidation resistance at high temperature), high resistance to corrosion, and good weldability.
However, the weldability of nickel and nickel alloys depends on several factors such as the composition, the welding process, and the welding conditions.
This article, by MaterialWelding, provides a comprehensive overview of the weldability of nickel and nickel alloys.
It covers the characteristics of nickel and nickel alloys, their weldability, the factors that affect their weldability, and the best practices for welding them.
Whether you are a welding engineer, a material specialist, or a student studying welding technology, this article will help you gain a better understanding of the weldability of nickel and nickel alloys and how to weld them effectively.
What is Nickel?
Nickel is a chemical element with the symbol “Ni” and atomic number 28. It is a silvery-white, hard, ductile, and lustrous metal that belongs to the transition metals and is located in the middle of the periodic table.
The UNS (Unified Numbering System) designation for nickel is N02200, and it is also referred to as Alloy 200.
The density of nickel is 8.908 g/cm³, which makes it one of the densest elements.
Nickel has several unique characteristics, including:
- Good ductility and high tensile strength.
- Excellent resistance to corrosion and oxidation, particularly in alkaline environments.
- Magnetic properties, making it useful in electromagnets and electric guitar strings.
- High melting point (1453 °C) and boiling point (2732 °C).
- Forms alloys with many other metals, including iron, copper, and chromium, resulting in enhanced strength, corrosion resistance, and heat resistance.
Nickel is widely used in various industrial applications, including the production of stainless steel, alloys, electroplating, batteries, and electronics.
Common Nickel Alloy Grades
Nickel alloys are a group of alloys that contain a high percentage of nickel as their main alloying element, along with other elements such as chromium, molybdenum, iron, and copper.
Nickel alloys exhibit excellent mechanical properties, high resistance to corrosion and oxidation, and good weldability, making them suitable for a wide range of industrial applications.
Some of the most common nickel alloy grades include:
- Inconel 600 – contains 72% nickel, 14-17% chromium, and small amounts of iron and copper. It has high strength and excellent resistance to corrosion and oxidation.
- Inconel 625 – contains 58% nickel, 20-23% chromium, and small amounts of molybdenum, niobium, and iron. It has high strength and excellent resistance to corrosion, oxidation, and fatigue.
- Hastelloy C276 – contains 57% nickel, 15-17% molybdenum, 4-7% iron, and small amounts of tungsten and cobalt. It has excellent resistance to corrosion and oxidation in harsh environments.
- Monel 400 – contains 67% nickel, 23% copper, and small amounts of iron, manganese, and silicon. It has good mechanical properties and excellent resistance to corrosion in a variety of environments.
- Nickel 200 – contains 99.6% nickel, with small amounts of iron and other elements. It has good mechanical properties and excellent resistance to corrosion in alkaline environments.
- Nickel 201 – similar to Nickel 200, but with lower carbon content for improved resistance to corrosion in reducing environments.
Nickel Rod Welding
Nickel can be welded using Stick Welding, TIG Welding, and MIG welding applications.
The Most Commonly used Nickel Rods for Nickel welding are:
|Sr. No.||Nickel Grade||AWS Rod Classification||ISO 18274 Classification|
|1.||Pure Nickel||ENi-1 (Stick welding), ERNi-1 (TIG & MIG Welding)||Ni 2061|
|2.||Monel||ENiCu-7 (Stick welding), ERNiCu-7 (TIG & MIG Welding)||Ni 4060|
|3.||Alloy 600||ERNiCr-3 (TIG & MIG Welding)||Ni 6082|
|4.||Alloy 625||ENiCrMo-3 (Stick welding), ERNiCrMo-3 (TIG & MIG Welding)||Ni 6625|
|5.||Alloy 800||ENiCrMo-3/ ENiCrFe-3 (Stick welding), ERNiCrMo-3 (TIG & MIG Welding), Bohler 21/33 MNNb||Ni 6625|
Nickel Welding Wires
Nickel welding wires are specialized welding consumables used for joining and overlaying nickel alloys, which are known for their excellent resistance to high-temperature and corrosive environments.
Here is a brief overview of some commonly used nickel welding wires and their applications:
- ERNi-1: This welding wire is primarily used for welding nickel 200 and 201, which are pure nickel alloys with good corrosion resistance and excellent thermal and electrical conductivity. It can also be used for welding nickel-copper alloys.
- ERNiCu-7: This welding wire is used for welding alloys such as Monel 400 and R-405, which are nickel-copper alloys with excellent corrosion resistance in marine and chemical environments. It is also used for welding other nickel-copper alloys, such as Inconel 625.
- ERNiCrMo-3: This welding wire is used for welding nickel-chromium-molybdenum alloys such as Hastelloy C-276, which are highly resistant to corrosion and cracking in aggressive chemical environments.
- ERNiCr-3: This welding wire is used for welding nickel-chromium alloys such as Inconel 600 and 601, which are used in high-temperature applications such as furnace components and heat exchangers.
- ERNiFeCr-2: This welding wire is used for welding high-temperature alloys such as Incoloy 800 and 800H, which are used in furnace and heat-treating applications.
- ERNiCrMo-10: This welding wire is used for welding nickel-chromium-molybdenum alloys such as Hastelloy C-22, which are highly resistant to corrosion and cracking in aggressive chemical environments.
- ERNiMo-7: This welding wire is used for welding nickel-molybdenum alloys such as Hastelloy B-2 and B-3, which are highly resistant to corrosion and cracking in reducing environments.
Nickel Stick Welding
Nickel stick welding electrodes are classified according to the American Welding Society (AWS) AWS A5.11, which designates each electrode with a unique code based on its composition and characteristics.
For pure Nickel, the most commonly used stick welding rod is ENi-1. The chemical compositions of ENi-1 are:
- Carbon (C): 0.10% maximum
- Manganese (Mn): 0.75% maximum
- Silicon (Si): 1.25% maximum
- Iron (Fe): 0.75% maximum
- Nickel (Ni): 92% minimum
- Copper (Cu): 0.25% maximum
- Aluminum (Al): 1.0% maximum
- Titanium (Ti): 1.0- 4.0%
The minimum tensile strength of ENi-1 rod is 60 Ksi (410 MPa) with a minimum of 20% elongation. It is used for welding N02200 or N02201 materials.
Stick welding of Nickel is carried out using DCEP welding polarity. ENi-1 offers good weldability.
Nickel TIG Welding
ERNi-1 is a type of nickel TIG & MIG welding filler metal that is primarily used for welding pure nickel alloys such as nickel 200 and 201.
The composition of ERNi-1 is as follows:
- Nickel (Ni): 93.0% minimum
- Iron (Fe): 1.0% maximum
- Carbon (C): 0.15% maximum
- Manganese (Mn): 1.0% maximum
- Silicon (Si): 0.75% maximum
- Copper (Cu): 0.25% maximum
The high nickel content in ERNi-1 provides excellent corrosion resistance and thermal and electrical conductivity.
The low levels of carbon and other impurities help to minimize the risk of porosity and cracking during the welding process.
Nickel MIG Welding
Nickel MIG (Metal Inert Gas) welding is a process used to join or overlay nickel alloys using a consumable wire electrode and a shielding gas such as pure argon.
ERNi-1 is a type of nickel MIG welding wire that is primarily used for welding pure nickel alloys such as nickel 200 and 201.
How to Weld Nickel to Steel?
Welding of Pure Nickel to Steel is carried out using ENi-1 or ERNi-1 welding electrodes.
Nickel alloys such as Monel to Steel welding are carried out using ENiCu-7 Stick welding electrode or ERNiCu-7 TIG & MIG filler wire.
When TIG or MIG welding, pure argon gas is used for gas shielding and purging. Purging with inert gas is required for Nickel welding to avoid oxidation of Nickel and other alloying elements.