Is Stainless Steel Electrically Conductive?

In our everyday lives, we all use stainless steel products. Have you ever pondered why we don’t use steel instead?

Stainless steel, on the other hand, is very resistant to rusting, making it ideal for industrial applications. Have you ever considered its electrical conductivity?

Is stainless steel an electrical conductor? It certainly does. Stainless steel is a metal alloy that conducts electricity but is not as strong as copper or aluminium. As a result, stainless steel is a poor electrical conductor. While carbon steel has an eight-fold higher resistivity than copper, stainless steel has a 40-fold higher resistivity than copper.

Did you know there are many types of stainless steel?

Every type of stainless steel has its own unique properties. The features of stainless steel as an electricity conductor will be discussed in this article.

But first, let’s take a look at what it’s made of chemically. Also, do you have a good understanding of electrical conductivity?

To satiate your curiosity, stick with us until the end.

What is the definition of stainless steel?

Stainless steel is a metal alloy made up primarily of iron and chromium, as well as additional elements such as nickel. It has a chromium content of roughly 10% to 30%.

The exact components of stainless steel vary depending on the type of stainless steel we desire and the application.

Aluminum, copper, titanium, nickel, molybdenum, nitrogen, sulphur, phosphorus, and selenium are just a few of the other components included to this alloy.

These additions improve the stainless steel’s corrosion resistance, provide it unique properties, and keep it rust-free.

Are you aware that stainless steel is nearly 100% recyclable? It has an endless number of recycling possibilities. This property of the alloy qualifies it as a “green material.”

Because stainless steel is an inert alloy and hence environmentally neutral, it is a green material.

It also does not emit any pollutants that are harmful to the environment.

Stainless steel is a gift to both humans and the environment. It is a perfect material for use in industries, structures, transportation, research, and logistics because of its excellent visual appeal, long durability, strength, and ease of maintenance.

Let’s take a closer look at the various types and grades of stainless steel and see how they differ.

Stainless Steel Types

Most of you are probably aware that stainless steel is primarily utilised for its corrosion resistance and rust resistance.

But, if it merely serves this role, why do we need so many different types? In this part, we’ll figure out how to do just that.

Stainless steel is divided into five key categories that allow it to endure a variety of settings and conditions.

The microstructures of these groups are used to classify them.

Stainless steel that is austenitic

Austenitic stainless steel is a type of stainless steel with austenite as the predominant microstructure. Do you know what the word austenite means?

Austenite is an iron and carbon-based solid solution. When the critical temperature reaches over 723 degrees Celsius, this solution is formed.

This stainless steel is 70% austenitic, with a minimum of 16% chromium and 6% nickel. Austenitic stabilisers are employed to create the austenite microstructure. It’s a non-magnetic material.

It has outstanding features such as tremendous strength and hardness, as well as resistance to extremely high temperatures.

Stainless Steel with Ferritic Ferritic Ferritic Ferritic Ferritic Ferr

Ferritic stainless steel is a form of stainless steel in which the only addition is chromium. It has a chromium content of 10.5 to 18 percent. It has inferior fabrication when compared to austenitic stainless steel.

properties, as well as a lower resistance to corrosion.

So, what’s the big deal about it? It is better than austenitic stainless steel in terms of engineering capabilities, and it is also magnetic. It also has a high level of stress corrosion resistance.

Stainless Steel Duplex

Duplex stainless steel is made up of both austenitic and ferritic stainless steels. This stainless steel has a high chromium content and a low nickel content.

Because duplex stainless steel is a mix of austenitic and ferritic stainless steel, it has the best of both worlds.

Because of the strength of this combination, it possesses great tensile strength as well as good weldability.

Despite the fact that duplex stainless steel has superior stress corrosion resistance, ferritic stainless steel outperforms it. It has a lesser toughness than austenitic steel but a higher toughness than ferritic steel.

Stainless Steel Martensitic

Martensitic stainless steel is a type of stainless steel with a high carbon content and a low chromium content.

Even if the chromium and alloy content of austenitic, ferritic, and martensitic stainless steels are the same, martensitic stainless steel has a lower corrosion resistance.

It has an outstanding hardenability feature. What’s more, guess what? When heat-treated, its characteristics can further enhance.

Stainless Steel Precipitation Hardening

Precipitation hardening stainless steel is a type of stainless steel that combines austenitic and martensitic characteristics.

The capacity to harden and create high tensile strength by heat treatment is ideal proof of this combination.

The addition of one or more additions, such as copper, aluminium, or titanium, hardens this form of stainless steel.

This type of stainless steel contains nickel and chromium as alloying components. It’s particularly important in high-speed applications, such as turbine blades.

Stainless Steel Grades

Different stainless steel grades are identified using the American Iron and Steel Institute (AISI) method.

This system assigns three-digit numerals to different metal alloys, starting with 2, 3, and 4.

The 200-series

The 200 series is made of manganese-containing austenitic stainless steel. Nickel concentration is minimal in this grade (below 5 percent).

The 200 series is used to make cutlery, washing machines, and other items.

The 300-series

Austenitic stainless steels with nickel, carbon, and molybdenum are used in the 300 series.

While molybdenum enhances corrosion resistance in acidic environments, nickel promotes ductility.

The 300 series is used in the motor sector, jewellery, and other fields.

The 400-series

The stainless steel in the 400 series is made up of martensitic and ferritic stainless steel. It has a good strength and corrosion resistance and can be heat treated. However, it has a poorer corrosion resistance than the 300 series.

The 400 series is utilised as both decorative steel and automotive trim.

What is the definition of electrical conductivity?

In layman’s terms, electrical conductivity refers to a material’s capacity to carry current.

It’s a property that determines how well a material conducts electricity.

The amount of voltage necessary for a certain quantity of electric current to flow is also a measure of electrical conductivity.

It’s denoted by the sign and measured in S/m (Siemens per metre).

Conductors are materials with a high electrical conductivity, such as aluminium and copper, while insulators are materials with a low or no conductivity, such as rubber.

The terms electrical conductivity and electrical resistivity are often used interchangeably. It’s because electrical conductivity is the inverse of electrical resistivity, or vice versa.

The formulae below can be used to describe their relationship:

1/ =================

where and are electrical conductivity and electrical resistivity, respectively.

The resistivity of a material having a homogenous cross-section area is now:

= RA/l = RA/l = RA/l = RA/l =

where R is the electrical resistance, A is the cross-sectional area, and l is the material’s length.

The following is a ranking of metals and metal alloys in terms of electrical conductivity, from best to worst:

Silver is pure.

Copper in its purest form

Gold is pure gold.

Aluminum

Zinc

Nickel

Brass

Bronze

Iron that is 100% pure

Platinum

Steel that has been carbonised

Lead in its purest form

Stainless Steel is a material that is resistant to corrosion.

If you closely examine the list, you’ll notice that stainless steel has the lowest conductivity of all the metals and metal alloys included.

Stainless Steel’s Electrical Conductivity

Unlike most metals, stainless steel, although being a metal alloy, is a poor conductor of electricity. Its electrical conductivity is significantly lower than that of silver and copper.

Silver and copper have conductivities of 6.3010 7 S/m and 5.9610 7 S/m, respectively, at 20 degrees Celsius, while stainless steel has a conductivity of 1.4510 6 S/m.

As a result, silver, the most conductive metal, has an electrical conductivity over 60 times that of stainless steel.

Although stainless steel has a low electrical conductivity, it has a high electrical contact resistance (ECR) due to the existence of a protective oxide layer, which limits its use in electrical connectors.

Electrical connectors are mostly made of copper alloys and nickel-coated connectors with low ECR values.

Stainless steel connections are only used where the design standards are stringent and great corrosion resistance is required, such as in severely oxidising situations or at high temperatures.

Perhaps you’re unsure what contact resistance entails. It is a material’s resistance to the flow of electricity caused by surface contacts.

Even carbonised steel has a better conductivity than stainless steel, as shown in the above list of ranking metals and metal alloys.

Did you know that the most prevalent grades of stainless steel used in the electronic sector because of their great corrosion resistance are Type 304 and Type 316?

Electrical enclosures for floor mounts, freestanding junction boxes, and wall mounts are also made of stainless steel.

Finally, some thoughts

By the time we get to the end of the article, we can answer the first question by claiming that stainless steel is a poor conductor of electricity in comparison to other metals and metal alloys. Electrical connectors are made of stainless steel grades 304 and 316.

Stainless steel, despite its low electrical conductivity, is extremely valuable and has effectively replaced steel in a variety of industries. Stainless steel, on the other hand, does not rust. As a result, all stainless steel products have a longer shelf life.

Because of its long life and ability to be recycled, it is critical that we use it more frequently rather than wasting our limited resources.

Read more: Is Brass a Combination? – Is it better to be homogeneous or heterogeneous?

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.

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