Plating metal has been done for hundreds of years. Plating is done for a number of reasons, and it’s an essential part of modern industries. Plating steel parts allows us to use them in a much wider variety of industries and use cases.
Plating steel with Zinc or Chromium has similar benefits to anodizing aluminum, and the process can be similar.
In this article, we’ll share the benefits of plating steel, different methods we use to plate steel parts, and more.
Steel is the most commonly used metal in the world. But on its own, steel has some significant disadvantages. The main issue with steel is that it’s subject to rust and corrosion when it’s exposed to moisture.
Plating steel parts reduces corrosion, increases the hardness, improve wearability, reduces friction, and can alter conductivity. There are a few different types of plating, and they each have unique pros and cons.
One of the primary benefits of plating steel is the increased resistance to wear. Steel is a hard metal with high yield and tensile strength, but it’s more subject to corrosion. When steel parts are plated with a protective material, the longevity and durability increases.
Metal plating protects steel parts from chemical damage, friction, and corrosion.
Another benefit of plated steel is a better aesthetic appearance. After machining the steel parts, they can be electroplated, or plated with zinc or chromium. The plating process reduces minor imperfections and scratches, and prevents future rust. Plating steel also makes parts easier to clean making routine maintenance faster and easier.
Zinc is one of the most common materials used in plating processes. Zinc plating, also called electro-galvanizing, involves adding a thin layer of zinc to the outside of a steel part. Zinc plating can still rust and doesn’t prevent all corrosion, but it rusts at 1/30th the rate of steel.
The parts are immersed in a chemical solution of zinc and an electrical current is used to apply the layer of zinc. Zinc plating usually adds a thickness between 5μm and 25μm (0.005mm-0.025mm).
There’s also a process called cold galvanizing. Essentially, this process adds a layer of zinc-rich primer. This does offer some protection against rusting, but as soon as it’s scratched, moisture can reach the underlying steel causing rust and corrosion.
Chrome plating (also called chromium plating) adds a hard and shiny layer of nickel to steel parts. This technique uses electroplating to add chromium to the outside of the steel.
The layer of chromium is used to add aesthetic appeal, reduce corrosion, increase the hardness of the parts, and make cleaning easier. If the plating is done for pure aesthetic reasons, a cheaper imitator of chrome is used.
Most of the car parts that are referred to as “chrome”, are steel parts that have been plated several times. This ensures that the chrome plating can withstand temperature changes and weather that a car is subject to. Triple plating is the most durable process. This plates the steel with copper and then nickel before the chromium plating.
Electroless nickel plating, also known as enickel or NiP, offers many advantages. This process results in a more uniform layer over more complex part surfaces. This plating is commonly used for ferrous metals steel, and offers better corrosion resistance compared to electroplating.
Electroless Nickel plating is commonly used in the aerospace and automotive industries, but the cost of plating is usually higher than electroplating.
Galvanizing is another plating process that adds a layer of zinc to the steel parts. This is typically done by hot galvanizing, where the parts are dipped into a bath of molten hot zinc.
The hot dip leaves a thicker coating of zinc compared to electro-galvanising. This plating offers better durability, but it’s not suitable for all parts. Smaller nuts, bolts, and threaded parts need a thinner layer of zinc to maintain their original features and function. The protection provided by hot-dip galvanizing is insufficient for products that will be constantly exposed to corrosive materials such as acids, including acid rain and outdoor uses.
This graphic compares the amount of material added to steel parts using different plating processes:
Is plating better than stainless steel?
Chrome plating looks similar to stainless steel, but how do they compare side-by-side?
Stainless steel is an alloy mix of chromium and nickel; it needs to contain at least 10.5% chromium to be considered stainless steel. Stainless steel is also resistant to corrosion and staining. It’s low maintenance and very durable.
Stainless steel is more durable than chrome plating, but it’s also heavier and more expensive.
Plated steel may be able to replace stainless steel in certain applications, but it depends on what the part is being used for. The resistance level of plated steel mostly depends on the thickness of the plating, and the environment the part is being used in.
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