Monel® vs. Stainless Steel: What Are the Key Differences?

Stainless steel and Monel may both be classed as alloys and even share many of the same characteristics, but their composition, uses, and strengths and weaknesses are quite different. This article is for all of our customers who want to know which alloy to use for their specific manufacturing needs. If you’d rather watch an explanation of these differences, playthe video below.

What is Monel?

Monel is an alloy that’s usually made up of 66% nickel and 31.5% copper, with trace amounts of manganese, carbon, iron, and silicon. It isn’t made with traditional direct ore smelting methods, but rather with precise computerized control in air induction furnaces. Its specific composition makes Monel extra strong but also gives it its greatest attribute by far: remarkable corrosion resistance. It can hold its own in corrosive environments and high heat, and won’t deform or lose its structure. You can weld with it, and it’s also non-magnetic.

Many industries, especially chemical and hydrocarbon processing, have cottoned on to this alloy’s extraordinary features, and use it to make everything from fittings to heat exchangers. Like most metals, it has a shiny surface, but its slightly yellow color is quite distinct, as you can see in the picture below:

There are a few caveats, though. If Monel comes in contact with a different metal and an electrolyte, it could experience galvanic corrosion due to the electrical interaction between the metals (kind of like how a good apple can start to rot next to a bad one). While it does have good heat resistance, it is not as high as some other alloys, and its density means it won’t be suitable for making lightweight objects. To machine Monel, you’ll need specialized processes and tools. It’s also not as readily available as some other materials, so you might yourself struggling to get a hold of some.

What Is Monel Made Of?

Monel, a nickel-copper alloy developed in 1905, consists primarily of 66% nickel, and 31.5% copper. This particular combination is the source of this alloy's exceptional strength and corrosion resistance. Traces of iron, manganese, carbon, and silicon are also present in Monel. Modern Monel manufacturing uses precise computerized control in an air induction furnace, as opposed to its traditional method of direct ore smelting.

What Are the Different Types of Monel?

There are a few different types of Monel, a few of which we list below:

• Monel 400 (Phyweld 400 or Nicorros LC): Used a lot in chemical and marine applications
• Monel 401: Great for self-fusing and resistance welding (even though it was originally designed for specialized electronics)
• Monel 404: Used in electronics thanks to its good brazing qualities and low Curie temperature 
• Monel 405 (Monel R405): A free-machining grade used to make components that need to be seawater resistant
• Monel 502: An easily machinable type, with good creep and oxidation resistance
• Monel K-500: Ideal for oil-well drill collars and marine pump shafts.

What Is Monel Used For?

The corrosion resistance and high strength of monel alloys make them ideal for a wide range of applications in the chemical and hydrocarbon processing industries for: heat exchangers, pumps, valves, fittings, shafts, and fasteners. Monel alloys are a popular option in a variety of industries in which dependability and longevity are essential due to their remarkable resilience and tolerance to hostile environments.

What Are the Advantages of Monel?

The advantages of Monel include:

1. Exhibits exceptional corrosion resistance, making it suitable for harsh and corrosive environments.
2. Known for their robust strength, Monel alloys maintain structural integrity even in challenging conditions.
3. Maintains its performance at elevated temperatures, expanding its utility in various industrial applications.
4. Resists deformation under long-term exposure to high temperatures and stress, ensuring durability.
5. Possesses low magnetic permeability, making it suitable for applications in which magnetic interference is a concern.
6. Demonstrates ease of weldability, facilitating efficient fabrication and construction processes.

What Are the Disadvantages of Monel?

The disadvantages of Monel include:

1. Can be less readily available compared to more common materials, potentially impacting accessibility.
2. Machining Monel alloys can pose challenges, requiring specialized tools and processes.
3. Monel has a fairly high density, which may be a consideration in applications for which weight is a critical factor.
4. In certain conditions, Monel may be susceptible to galvanic corrosion when in contact with dissimilar metals.
5. While Monel demonstrates temperature resistance, there are limitations to its heat resistance compared to some other alloys, affecting its performance in extremely high-temperature environments.

Is Monel Heavier Than Stainless Steel?

Yes, Monel is generally heavier than stainless steel. Monel alloys have a higher density compared to most stainless steel grades, contributing to their greater weight. This difference in weight can be a consideration in applications in which material weight is a critical factor in design and functionality.

What is Stainless Steel?

Stainless steel is arguably the most well-known and used alloy (if you look around you, we’ll bet you’ll find something made from it within a few seconds). It’s sometimes called “inox” or rustless steel and is made of around 70–80% iron, with at least 10.5% chromium for the protective oxide layer bonus. It also has around 1.2% of carbon, as well as trace amounts of other elements like nickel and manganese, which all help to make it stronger, adaptable, more durable, and corrosion-resistant. 

There are many different grades of stainless steel that can be made into everything from industrial machinery and construction equipment to kitchenware. Less ductile grades are used for things like knives and other utensils, while more ductile grades are used for saucepans, sinks, grills, and other cookware.

As you can see, stainless steel has that typical metal look, is most often silvery in color, and super shiny. It’s not only its good looks that make it a go-to for homewares; it’s also considered a hygienic material because its nonporous surface is easy to keep clean. This also makes it good for medical equipment.

As much as we’d like to use it for everything, stainless steel isn’t ideal for lightweight products because it has a good amount of heft to it. It’s hard to cold work, can be annoyingly magnetic in some grades, and, although it will last practically forever, it’s not immune to the odd scratch or dent. It’s also more expensive than some other materials.

What Is Another Name for Stainless Steel?

Stainless steel, sometimes referred to as inox, is alternatively known as corrosion-resistant steel (CRES) or rustless steel. These terms are interchangeably used to describe this alloy, emphasizing its key attributes of corrosion resistance and durability across various applications.

What Is Stainless Steel Made Of?

Stainless steel is composed of iron, with a crucial inclusion of at least 10.5% chromium, which forms a protective oxide layer. Its strength, resilience to corrosion, and adaptability are further enhanced by the presence of other alloying elements including nickel and manganese, which total less than 1.2% of the material.

What Does Stainless Steel Look Like?

Figure 2 shows an image of stainless steel machined parts from Xometry:

What Are the Different Types of Stainless Steel?

If you have some time on your hands to learn about all the different stainless steel types and grades (there are over 100!), you can read all about them in our detailed guide. In the meantime, here are some of the common ones:

• Austenitic (304 and 316): The most popular type, with great corrosion resistance and non-magnetic properties
• Low-carbon ferritic (409 and 430): Often used in automotive and architectural industries, but are less hardenable than other types 
• Austenitic-ferritic: Also known as “duplex”, these combine all the good stuff from the two types in the name, and are ideal for chemical processing
• Martensitic: Strong and durable, can be hardened by heat-treatment, and is used in surgical tools and cutlery
• Precipitation-hardened: One of the strongest options, commonly used to make aerospace parts.

What Is Stainless Steel Used For?

Stainless steel is widely used in the production of cookware, cutlery, and kitchen accessories. Less ductile grades are typically used for utensils such as knives, but more ductile grades are used when making saucepans, cookers, sinks, and grills. Stainless steel stands out as a fundamental material in both home and industrial contexts due to its wide range of applications.

What Are the Advantages of Stainless Steel?

The advantages of stainless steel include:

1. Exhibits excellent corrosion resistance, ensuring longevity in diverse environments.
2. Withstands wear and tear, contributing to its long-lasting performance.
3. The non-porous surface of stainless steel makes it easy to clean, promoting hygiene in applications like kitchenware and medical equipment.
4. Stainless steel's strength and structural integrity make it suitable for a wide range of applications, from construction to industrial equipment.
5. Beyond functionality, stainless steel's sleek and modern appearance enhances the aesthetic appeal of products in various industries.

What Are the Disadvantages of Stainless Steel?

The disadvantages of stainless steel include:

1. Can be relatively expensive compared to other materials, impacting overall project costs.
2. The density of stainless steel is quite high, which may be a consideration in applications in which weight is critical.
3. Certain stainless steel grades exhibit magnetic properties, which may be undesirable in certain applications.
4. While durable, stainless steel is susceptible to scratches and dents, affecting its appearance over time.
5. Cold working stainless steel can be challenging, requiring specialized tools and processes.
6. Variations in the appearance of stainless steel can occur, impacting the desired aesthetic consistency in some applications.

Is Stainless Steel Softer Than Monel?

Yes, Monel is generally stronger than stainless steel. Monel's composition, including nickel and copper, contributes to its higher strength compared to stainless steel, making it a preferred choice in certain applications.

How To Choose Between Monel and Stainless Steel?

To choose between Monel and stainless steel:

1. Corrosion Resistance: If the application involves exposure to highly corrosive environments, such as: saltwater, acidic or alkaline solutions, or chemicals, Monel may be the better choice due to its exceptional corrosion resistance. Stainless steel is also corrosion-resistant but may be less suitable for extremely aggressive environments.
2. Strength and Durability: If high tensile strength and durability are critical, stainless steel is a strong and durable material suitable for various structural and load-bearing applications. Monel is also durable and has generally higher strength compared to stainless steel except for a few exceptional grades.
3. Cost Considerations: Evaluate the budget constraints for your project. While both Monel and stainless steel offer durability, Monel is often more expensive. Consider the financial implications of material selection.
4. Machinability: Consider the ease of machining required for your project. Stainless steel may be more readily machined than Monel, which can impact fabrication processes and costs.
5. Magnetic Properties: Assess the magnetic properties needed for your application. If non-magnetic properties are crucial, Monel may be preferred over certain stainless steel grades.

What Are the Properties of Monel and Stainless Steel?

Table 1 highlights the properties of Monel and stainless steel:

How Ductile Are Monel and Stainless Steel?

Monel exhibits remarkable ductility, outperforming stainless steel and many other metals. Ductility refers to a material's capacity to deform under tensile stress without fracturing. Monel's exceptionally ductile nature allows for effortless shaping into intricate forms, showcasing its versatility across diverse applications.

What Is the Tensile Strength of Monel and Stainless Steel?

Tensile strength, which indicates a material's maximum ability to withstand stress under tension, demonstrates how much better Monel K500 is than stainless steel 316. Approximately 700 MPa is the remarkable tensile strength of Monel K500, which is more than the 550 MPa of stainless steel 316. This discrepancy highlights Monel's superior resistance to applied forces, making it a strong option for challenging structural situations.

Do Monel and Stainless Steel Rust?

Yes, Monel and stainless steel can both corrode, but Monel generally exhibits higher corrosion resistance due to its higher nickel content. Monel's increased nickel concentration enhances its ability to withstand corrosion, especially in challenging environments like exposure to saltwater. In contrast, stainless steel, while corrosion-resistant, may show signs of rust over time, particularly in harsh conditions.

Are Monel and Stainless Steel Brittle?

No, Monel and Stainless Steel are not inherently brittle. While ferrous materials like stainless steel tend to become brittle at low temperatures, Monel differs. It exhibits increased mechanical strength with min

How To Identify Monel and Stainless Steel?

You can use these steps to distinguish between stainless steel and Monel. Start by examining the material's magnetic properties. Monel is not magnetic, while stainless steel can be, so if the tested piece is magnetic this means that the material cannot be Monel. Next, note the hue: The color of Monel is usually yellowish or silvery, while the color of stainless steel is silver or gray. Examine Monel's resistance to corrosion; it works well in maritime settings. Do a spark test as well. Stainless steel makes more sparks than Monel, which either produces fewer sparks or is spark-resistant.

What Are the Applications of Monel and Stainless Steel?

Applications of Monel and stainless steel include the following:

Monel:

1. Marine Engineering
2. Chemical Processing
3. Aerospace Components
4. Oil & Gas Industry
5. Electrical and Electronic Parts

Stainless Steel:

1. Construction
2. Medical Equipment
3. Automotive Industry
4. Kitchen Appliances
5. Architecture

Monel is favored in marine and chemical environments due to its superior corrosion resistance, while stainless steel finds widespread use in construction and medical applications, showcasing its versatility in various industries.

Is Monel Magnetic?

No, Monel is typically non-magnetic because it lacks iron in its composition. Iron is the element that imparts magnetism to metals, and without it Monel cannot be magnetized. Monel's non-magnetic properties make it a good choice for applications involving MRI-compatible implants in the medical area or electrical connectors in electronics production. But some Monel alloys might have traces of iron in them, which would make them magnetic to a small extent.

Is Stainless Steel a High-Quality Metal?

Yes, stainless steel is considered a high-quality metal. Its exceptional biological cleanability, superior to aluminum and copper and comparable to glass, makes it a preferred choice in applications demanding hygiene, such as pharmaceutical and food processing plants. The combination of cleanability, strength, and corrosion resistance contributes to stainless steel's reputation as a high-quality material.

How Much Do Monel and Stainless Steel Cost?

Prices for Monel metal normally range from $2.50 to $3.00 per pound. As opposed to this, stainless steel is often less costly, costing between $0.34 and $0.66 per pound. The disparity in price can be attributed to the different expenses involved in the production, availability, and composition of stainless steel and Monel.

Copyright and Trademark Notice

1. Monel® is a trademark of Special Metals Corporation

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