Low carbon steel is usually made into flat-rolled sheets and strips, used for shipbuilding, wire, vehicle bodies and domestic appliances. It’s widely used for fabrication and panelling because it can’t be altered by heat treatment. Carbon steel with the lowest possible amount of carbon is called ‘wrought iron’, used for fencing, gates and railings, hard but not brittle. Medium carbon steel is a lot easier to machine and adding small amounts of silicon and manganese improves the quality. Also called mild steel, it’s commonly used structurally in buildings and bridges, axles, gears, shafts, rails, pipelines and couplings, cars, fridges and washing machines. High carbon steel has a much better tensile strength, used to make cutting tools, blades, punches, dies, springs and high-strength wire. Ultra high carbon steel is brittle and very hard, and can’t be cold-worked. It’s used to make extremely hard components like blades, cutting tools and large machine parts, hot water radiators, industrial castings and metal lamp posts. It’s also called ‘cast iron’, and it’s the material used to make old fashioned cooking pots.