Inconel
Inconel is a registered trademark that refers to nickel-chromium superalloys with common characteristics. As they are austenitic nickel alloys, the Inconel family is also at times referred to as Chronin, Altemp, Haynes, Nickelvac, and Nicrofer. While Inconel alloys can differ widely in terms of composition, all feature nickel as the highest percentage element used, with chromium as the second highest percentage.
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Applications of Inconel Alloys
Inconel alloys are often used for these high temperature applications:
- Nuclear
- In which Inconel 718 is often used in nuclear reactors, rocket motors, and spacecraft.
- Chemical
- For processing equipment.
- Industrial Manufacturing
- In heat treating equipment, such as furnaces and various machines and components such as gas turbine.
- Marine
- For salt corrosion-resistant piping, springs, and fastener.
- Aerospace
- Where Inconel is used for piping, safety wire, shims, and other structural metal on aircrafts.
Manufacturing Process of Inconel Alloys
Since Inconel alloys rapidly harden under machining, they can be difficult to shape. Often, the Inconel alloy must be in a solutionized form for machining to occur. However, machining must be done aggressively and using hard tools, such as in welding or brazing stainless steel. Threaded inserts are commonly used. In addition, the most common welding technique that is used on Inconel alloys is gas tungsten arc welding (GTAW), which is more generally known as tungsten inert gas (TIG) welding. However, recent developments in pulsed micro laser welding are becoming an increasing popular technique for welding Inconel alloys as well.
Notable Types of Inconel Alloys
- Inconel 617
- An alloy of Ni, cobalt, chromium, and molybdenum. This exceptional combination improves its strength, oxidation resistance, and metallurgical resistance. The addition of aluminum enhances its resistance to oxidation. It can also resist corrosion even when exposed to different corrosive environments. It is used in ducting, transition liners, petrochemical processing, heat-treating equipment, nitric acid production, and gas turbines.
- Inconel 601
- An alloy of Ni, iron, and chromium. It is a versatile engineering material for various applications that require high levels of resistance to corrosion and heat. It has high strength; high resistance to aqueous corrosion as well as readily machined and welded. It has high levels of metallurgical stability and a high-temperature resistance of about 1250掳F. It has an adherent layer that is resistant to spalling. Inconel 601 is widely used in fabricated combustion chambers, thermal reactors, insulting cans, and refractory cans.
- Inconel 625
- Is 58% nickel, 20-23% chromium, 5% iron, 8-10% molybdenum, 3.15-4.15% niobium, 1% cobalt, and trace amounts of manganese, aluminum, titanium, silicone, carbon, sulphur, and phosphorus.
- Inconel 600
- Is 72% nickel, 14-17% chromium, 6-10% iron, 1% manganese, and trace amounts of copper, silicone, sulphur, and carbon.
- Inconel 718
- A nickel-chromium-cobalt alloy widely known for its superior metallurgical stability. The Inconel 718 alloy is widely used in chemical production, power generating plants, gas turbine, combustion cans, and ducting. It has high resistance to corrosive aqueous environments and oxidation at high temperatures. The addition of molybdenum and cobalt imparts a solid-solution strengthening. It is easy to fabricate, which makes it easy to join with metals using conventional welding techniques.
- Inconel 718 is 50-55% nickel, 19% chromium, 17% iron, 3% molybdenum, 5% niobium, 1% cobalt, 1% aluminum and trace amounts of manganese, copper, titanium, silicone, carbon, sulphur, phosphorus, and boron.
- Other alloys include 601, 690, 751, 903, and 939.