on the subject of Plasma cutters and flame cutting

I don't know the textbook answer, but I can tell you I've tried. It just sort of melts, rather than burning clean.

Grant

Cast iron is not homogenous material. Its got a random grain structure.

Gunner

It can be done... Take an 7018 arc rod and hold it in front of the flame of the torch... The free burnning metal of the rod will make it cut cast....

Do you remove the flux from the rod first or does the flux help?

Thank You, Randy

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dont know the chemical reason but it just sort of bubbles and melts, maybe all the carbon ?

you can cut it with a cold chisel faster than with a torch

The oxy-fuel cutting of carbon steel only works as well as it does because of the serendipitous confluence of three properties of carbon steel.

1. In the presence of pure oxygen it burns readily at a temperature below its melting point.

and

1. The slag produced by this burning, melts and becomes highly fluid at a temperature below the melting point of steel.

When you use a cutting torch on steel, you never really melt the metal. You heat it up until the excess oxygen will cause it to burn. As you push the torch along, the front of the cut stays a little hotter and burns more than the side. Meanwhile the slag is blown out of by the turbulence. Because the metal itself if not molten, it constrains the flow of oxygen and the burning to a narrow line which is why we can get a neat cut.

Cast iron and wrought iron melt before the slag becomes fluid. The result is that the burning is not self sustaining and you are left melting the parent metal and blowing it out of the way with the oxygen blast. This means that you get a ragged cut that only gets as deep as the flame of the torch.

Paul K. Dickman