Stainless steel is conductive because its electrons exhibit slight movement. However, compared to metals like silver and copper, the alloy (usually a combination of iron and chromium) falls into the category of materials that do not readily conduct electricity.
This and their strong corrosion resistance are why they are very popular among home and industrial applications like cutlery, facades, and food conveyors.
In this guide, I will explain why stainless steel conducts electricity poorly, its electrical conductivity, and the resistivity of the common types.
You will also find out if the alloy is a good conductor of heat and how it shapes up different applications.
Why Does Stainless Steel Conduct Electricity Poorly?
Most metals are good conductors of electricity because their valence (outermost shell) electrons move randomly within their crystal lattice. For poor-conducting metals like stainless steel, this is not the case.
Stainless steel is an alloy. It is mostly a mixture of iron, chromium, or other metals like nickel or carbon (to boost corrosion resistance). This inclusion of foreign metals alters the lattice of iron (the primary) and results in numerous inelastic collisions among molecules.
When the metal lattice is imperfect, metals or alloys like stainless steel will not be very conductive. Other examples of metals that do not conduct electricity are bismuth and tungsten.
Electrical and Thermal Conductivity of Stainless Steel
The electrical conductivity of any stainless steel is the rate at which it allows the flow of electricity through it or is conductive. For conductivity, the value rarely varies from 1.45×106 S/m.
On the other hand, heat conduction (thermal conductivity) varies for different stainless steel types because of the change in microstructure.
Let’s take a look at the various type of stainless steel and their thermal conductivity:
1. Austenitic type
Austenitic stainless steel is predominantly (about 70%) made of austenite – a solid solution of iron and carbon. Other metals that make up the alloy include chromium and nickel.
The thermal conductivity of austenitic stainless steel is 20 W/(m.K.). It is renowned for its extreme strength and resistance to high temperatures.
2. Ferritic type
Unlike austenitic stainless steel, only nickel (about 18%) is added to ferritic stainless steel. The stainless steel has a thermal conductivity of 26 W/(m.K).
While terrific stainless steel displays poor fabrication and poor resistance to corrosion, it is significantly magnetic
3. Duplex type
Duplex stainless steel is a hybrid stainless steel that combines austenitic and ferritic stainless steel. In other words, it has more chromium and less nickel.
The thermal conductivity of duplex stainless steel is 19 W/(m.K). In terms of advantages, it has high tensile stress and is weldable.
Its toughness, however, is lower than that of austenitic stainless steel but higher than ferritic steel.
4. Martensitic type
This type of stainless steel contains only carbon and a very low amount of chromium. If austenitic and ferritic stainless steel has the same amount of chromium as martensitic stainless steel, they would still not match its corrosion resistance.
The thermal conductivity of the alloy is 24.2 W/(m.K.). Aside from being corrosion resistant, martensitic stainless steel is tough, and all its properties get better with increased temperature.
5. Precipitation hardening type
For stainless steel to achieve a precipitation-hardening state, it must feature additives such as aluminum, copper, and titanium. These additives combine with the already existing iron, chromium, and nickel.
The thermal conductivity of this stainless steel is 18 W/(m.K.). They have a high tensile strength that gets better with heat treatment and are mostly used in turbine blades and other high-speed applications.
Uses of Stainless Steel
Materials with low thermal conductivity such as stainless steel naturally prevent heat transmission. This means better energy efficiency, material stability, and longevity.
Let’s see how true this is in their applications:
- Stainless steel is a major raw material for building facades and glass applications.
- Most ovens and conveyors used in food processing industries are stainless steel products.
- Kitchen appliances that last a very long time like sinks, cutlery, and knife blades are also stainless steel products.
- In medicine, they are used in designing surgical tools and surgical implants.
Does stainless steel conduct electricity better than steel?
Stainless steel does not conduct electricity better than steel. This is because its electrical conductivity is about 15 W/m.K lower than carbon steel.
What is the problem with stainless steel?
The major problem with stainless steel is that it overheats. This makes the removal of materials such as weld seams difficult.
Can stainless steel get ruined?
While stainless steels are highly corrosion resistant, they remain susceptible to surface damage.
This form of damage ensues as a result of long-term exposure to harsh conditions or poor maintenance.
Stainless steel is not a pure metal – it is an alloy. As a result, expecting it to conduct electricity the same way a pure metal would is unfair. Although some types such as grade 304 and 316 feature in electrical connectors, their capabilities are mild.
Despite boasting low electrical and thermal conductivity, stainless steel remains a versatile alloy. This is thanks to its longer shelf life and stability.
So if you wonder why your cutlery, knife, sink, or surgical equipment last for a very long time, there you have it.
I hope you found this article helpful. To know more about other metals and their conductivity, kindly check out metals that conduct electricity.
Thanks for reading.