Monel alloy not only has high strength and toughness, but also has excellent corrosion resistance to reducing acid and strong alkali media and sea water. Therefore, it is usually used to manufacture equipment for transporting hydrofluoric acid (HF), brine, neutral media, alkali salts and reducing acid media C23. Monel alloy is also suitable for dry chlorine, hydrogen chloride, high temperature chlorine (425℃) and high temperature hydrogen chloride (450℃), but it is not resistant to corrosion by sulfur-containing media and oxidizing media (such as nitric acid, media with high oxygen content) Because nickel reacts violently with sulfur and oxygen, it is easy to form Ni3S2 and NiO.
Uses of Monel alloy
The structure of Monel 400 alloy is a high-strength single-phase solid solution. It is a corrosion-resistant alloy with the largest amount, the widest application, and excellent comprehensive properties. Monel alloy has excellent corrosion resistance in hydrofluoric acid and fluorine gas media, and also has excellent corrosion resistance to hot concentrated lye. At the same time, it is resistant to corrosion from neutral solutions, water, sea water, air, organic compounds, etc. An important feature of Monel alloy is that it generally does not produce stress corrosion cracks and has good cutting performance.
Monel K500 (K500, NCu30-2-1, UNS N05500) alloy not only has excellent mechanical properties such as high strength, corrosion resistance, and non-magnetic properties, but also has the same corrosion resistance as Monel 400. It can be used as a pump shaft material and is suitable for working under the harsh geological mining conditions of high sulfur and high wax oil layers. Since Monel has no plastic-brittle transition temperature, it is very suitable for various low-temperature equipment. This alloy is mainly used for pump shafts and valve stems, conveyor scrapers, oil well drilling rings, elastic parts, valve pads, etc. It is suitable for petroleum, chemical shipbuilding, pharmaceutical and electronic sectors.
Corrosion resistance of Monel alloy
Monel alloy has excellent corrosion resistance in fluorine gas, hydrochloric acid, sulfuric acid, hydrofluoric acid and their derivatives. Acid medium: M400 is corrosion resistant in sulfuric acid with a concentration of less than 85%. M400 is one of the few important materials that can withstand hydrofluoric acid. Water corrosion: In most water corrosion conditions, M400 alloy has excellent corrosion resistance, and pitting corrosion and stress corrosion are rarely found. The corrosion rate is less than 0.025mm/a. High temperature corrosion: the highest temperature of M400 continuous working in the air Generally around 600℃, the corrosion rate is less than 0.026mm/a in high temperature steam. Ammonia: Due to the high nickel content of Monel 400 alloy, it can withstand corrosion under anhydrous ammonia and ammoniating conditions below 585°C.