Cutting cold rolled steel requires some knowledge about how the cold steel is made. It also requires some knowledge about how the steel operates and functions differently than hot rolled steel, and why hot cutting tools are a bad idea for cold steel. Here is what happens to cold rolled steel when you cut it with a hot tool/implement and how to avoid it.
The Molecular Structure of Cold Steel vs. Hot Steel
Hot rolled steel is heated above its recrystallization point, which means that when it cools, it does not need to be reheated to a very high temperature again to shape it. For instance, if you wanted to shape the hot steel into protective plating for a race car, you would only have to heat the hot rolled steel up to a point where it turns pliable to hammer and shape. This temperature would not be very high at all in comparison to cold rolled steel. With cold rolled steel, you have to heat the steel above the recrystallization point so that it becomes more pliable and easy to shape before you can even begin to shape it. Thus, the cold rolled steel would have to become hot rolled steel and change its molecular structure to a "softer" metal to do what you need it to do.
What Happens to the Cold Rolled Steel When You Cut it with a Hot Tool/Implement?
Now, let's say you want to cut a sheet of cold rolled steel. There are a couple of ways you could do this, but most manufacturers go straight for the hot methods because it cuts the steel the quickest. This is not always the best choice, since a lowtorch, welding tool, or plasma cutter, can alter the cold steel on the molecular level along the very edges of the cuts made. This leaves you with a cut sheet of steel that is very strong, thick and durable until you get to the edges, where it could be softer and potentially more brittle over time. If the edges of the piece you cut are irrelevant to the finished product, then it won't be a problem. However, if you want consistent hardness and the same molecular structure throughout the piece of steel, cut it another way.
Other Ways You Can Cut Cold Rolled Steel and Avoid Using a Hot Tool
Sure, cold rolled steel is not easy to cut, but there are other means to cut it. Punching can help you create perforations in the metal sheet in the shape or line you need. Cold punching will not affect your steel, and when the stamping creates a continuous line of holes along an edge, it makes it easier to separate the piece you need from the sheet of steel as a whole. Stamping machines equipped with diamond cutting blades may also be used.