Cold rolled vs. Hot rolled

[blacksmith]

Steel needs carbon to make it hard. Hot roll or cold roll do not have enough carbon to harden it. The other steels are alloy steels and they have carbon in them so they can be hardened. After you harden some steel you also have to temper it to draw some of the hardness off. If left in the full harden state it will my break. Tempering brings it to the hardness you would need for the application. You may not be able to do this at home with out the proper equipment to control temperature.

 

[whistlepig]

Hot rolled or cold rolled the steel is going to be rolled. That gives us the sizes we want. The "mix" of steel determines it's properties. For hard facing or for a wear resistant edge hardening would be enough as long as this hardened steel was supported by mild steel. If the hardened metal has to stand alone for strength then tempering would be required or it would break. Hardening is something than isn't all that hard to do with the proper steels. Tempering is a whole different beast and has to be done in a controlled environment like an oven.

 

[Gizmo2]

Cold rolled is probably about twice the cost of hot rolled. But if you need it, you need it.