This is the view from the end of Southport Pier looking towards Blackpool. You might spot Blackpool Tower if you magnify the picture but you might also notice that the pillar tells you that it is made of cast iron. I thought I knew about cast iron but my knowledge has turned out to be somewhat brittle, It turns out that cast iron has more carbon in it than steel. For years I've been thinking that it was purer because it was called iron. In a perfectly pure metal, the layers of atoms can slide over each other easily. The introduction of carbon molecules makes this harder because they are a different size to the iron atoms and disrupt the lattice, making the movement harder. The higher the carbon content, the more the layers are locked together. Steel is ductile. This means that there is some give in the metal before it breaks, in the same way that a Mars Bar loses its perfect shape and narrows as you pull on it. That distortion gives us a warning that it is going to break. The extra carbon in cast iron means that there is no give before it breaks. It snaps like a Rich Tea biscuit would. We say that it is brittle. I know this, having smashed an old cast iron gutter by clouting it with a hammer. It broke like glass. I'm sure that I was taught correctly about the carbon content of cast iron. I wonder at what point I lost that bit of information?
