Why is Monel so expensive?
Overview
If you are researching and comparing metals for precision machined parts, stainless steel may be the first choice you come across. Stainless steel is one of the most commonly used materials, but it is not suitable for every type of project. There are many other metals and alloys that you may not be familiar with. One of these lesser-known alloys is Monel.
Monel is a nickel-based alloy that is a more exotic and expensive structural material than steel alloys (mainly iron). By comparison, nickel prices are around $8-$9 per pound, while iron ore costs $0.08 per pound.
Monel is a trade name referring to a group of copper-nickel alloys. This alloy is much stronger than nickel alone, highly resistant to corrosion and highly weldable.
Spex uses Monel to machine custom fittings, adapters, manifolds, precision screws, pins and nuts.
Read on to learn more about Monel and its applications in today's world.
Strength and durability
High-temperature alloys such as Monel are commonly used in the oil and gas industry, chemical and petrochemical processing, power plants and other harsh environment applications. Metals and metal alloys are tested in several different ways to determine their strength and durability. This includes testing yield strength, tensile strength and corrosion resistance.
The yield strength of a material is calculated as the stress that the metal (or alloy in this case) can withstand without permanent deformation.
The tensile strength of a material is the maximum stress an alloy can withstand when stretched or pulled before failing or breaking.
Corrosion resistance refers to the degree to which a metal withstands corrosive environments in the presence of acids, salt water, or gases and oils.
Monel is a nickel-based alloy with excellent corrosion resistance. Specifically, Monel 400 is known for its toughness, which it maintains over a wide range of high and low temperatures.
We call Monel a superalloy because it maintains its strength in harsh environments of high temperature, high stress and high oxidation atmosphere. The yield strength of Monel alloy is as high as 350MPa, and the tensile strength is about 550MPa.
Monel alloy
Monel refers to a group of alloys containing approximately 63% nickel and 30-35% copper. The other 2-5% is a combination of iron, manganese, silicon, aluminum and titanium. Just like stainless steel comes in different alloys (316, 404, 304, etc.) Monel comes in 5 common alloys.
Monel 400: This alloy has good ductility and thermal conductivity. Monel 400 is commonly used in marine engineering, chemical and hydrocarbon processing, heat exchangers, valves and pumps.
Monel 401: This alloy is designed for specialized electronic applications. Monel 401 is easily autogenous weldable by the gas tungsten arc process.
Monel 404: The composition of Monel 404 has been carefully tailored to provide an extremely low Curie temperature, low permeability and good brazing characteristics. This alloy can be welded and forged using common welding techniques, but cannot be hot-worked
Monel 405: Monel 405 is an easy-to-process grade of Alloy 400. The percentages of nickel, carbon, manganese, iron, silicon and copper are the same as the 400, but the sulfur content is increased from a maximum of 0.024% to 0.025-0.060%. Alloy 405 is used in automatic screw machine blanks and is generally not recommended for other applications.
Monel K-500: Monel K-500 combines the excellent corrosion resistance of Monel 400 with increased strength and hardness. Enhanced properties are achieved by adding aluminum and titanium to a nickel-copper matrix and heating it under controlled conditions
Industries and applications
Since Monel is significantly more expensive compared to other options, it is limited to uses where cheaper alternatives are not available. Monel alloy is used in the aerospace industry, petroleum production and refining, marine equipment, and some instruments.
Monel is probably the most durable of all commonly used engineering alloys. The alloy is also resistant to many forms of sulfuric and hydrochloric acids under reducing conditions.
