Nickel & Nickel-Based Alloys
Inconel, Hastelloy, Monel, and Incoloy: materials for heat and aggressive media
AI generated Nickel-base alloys withstand what normal steels give up on: extreme temperatures, aggressive acids, seawater. The best-known representatives are Inconel, Hastelloy, Monel, and Incoloy. When , they are demanding – they tend to hot cracking and require the highest cleanliness.
is the element that makes steels tough and – and as the base for its own alloys, it becomes the material for the toughest jobs: gas turbines, power plants, chemical plants, seawater technology. Pure nickel ( 200/201) covers the chemical industry, but the real stars are the nickel-base alloys.
The most important families: (Ni-Cr) for high temperatures – turbine blades, furnace construction, exhaust systems. (Ni-Cr-Mo) for the fight against aggressive acids and . (Ni-Cu) for seawater and hydrofluoric acid. And Incoloy (Ni-Fe-Cr) as an economical compromise for moderate temperatures. All have one thing in common: they are expensive, and they don't weld like steel.
The biggest danger when is . Nickel-base alloys solidify with a coarse grain and are prone to solidification and liquation cracks, especially when the with the is unfavorable – too much iron or sulfur from an unalloyed steel makes the weld bead crack-sensitive. Therefore: keep the joint clean and grease-free, and keep the low.
Welding is almost always done with and low heat input. Nickel-base alloys can't handle high heat inputs – otherwise the grain in the coarsens irreversibly and the weld loses and corrosion resistance. No , small layers, keep interpass temperature low. Use argon as , and on the root.
Important when working with these materials: the weld bead shines metallic after if everything is right. Heat tint, slag, or tell you that your wasn't clean – and that's exactly when corrosion resistance is no longer right.