What is Metal Rolling? Do you know that metal can be reshaped, made more consistent, and even strengthened by squeezing it between rollers in a process called rolling?

There are two main types of rolled steel, hot rolled and cold rolled, each has unique properties that make them better suited for certain uses.

To pick the right rolled steel for your project, you need to understand the differences between these two types and how they impact how well they work.

What is Metal Rolling

In the world of metalworking, imagine giant rolling pins that can transform the thickness and evenness of metal. This process, known as rolling, has been around for centuries, shaping metal into countless useful forms.

Evidence of early rolling mills, called slitting mills, dates back as far as 600 BC in the Middle East and South Asia.

Fast forward to 1783, and Henry Cort, an English inventor, revolutionized rolling with his use of grooved rollers for shaping iron bars.

This innovation wasn’t just about shaping iron; it laid the groundwork for the modern rolling techniques we use today to create everything from car parts to building materials.

There are two types of metal rolling, the hot rolled and cold rolled, let’s get into it!

1. Hot Rolled Steel

To make hot rolled steel, really hot slabs of metal (above 1700°F) are squeezed between rollers. This makes the steel easier to bend and shape later on in the manufacturing process.

They start with a big block of metal called a billet, heat it up, and squish it flat. Then, while it’s still hot, they keep rolling it thinner using several sets of rollers until it’s the right size.

For flat metal like sheets, they roll it up into big coils to cool. For other shapes, they cut it up and package it after rolling.

Hot rolled steel offers several advantages, including:

Better Workability: The hot metals are easier to form and rolled
Lower Cost: Hot rolled still are generally less expensive due to it involves less processing.
No Internal Stress: Since the hot rolled steel involves a gradual cooling process, the material have the time to normalize its structure and become free of internal stresses.

Since hot rolled steel shrinks slightly during the cooling stage, its uses are generally in application that do not require tight tolerances, such as:

Railroad equipment (e.g., tracks and railcar components)
Agricultural Equipment
Construction
Automobile Parts

Also Read: Types of Steel

2. Cold Rolled Steel

Cold rolled steel takes hot rolled steel and puts it through a whole new wringer at room temperature. This extra step strengthens the steel and makes its dimensions more exact.

Unlike hot rolled steel which can be shaped easily because it’s hot and pliable, cold rolled steel needs a lot more force because it’s gone through the initial hot rolling process and cooled down, becoming less flexible.

This extra processing step makes cold rolled steel more expensive and time-consuming to produce compared to hot rolled steel.

But the extra effort pays off in the form of a smoother surface finish and highly accurate measurements, which can be crucial for certain applications.

Cold rolled steel offers several advantages, including: