- Iron ore contains iron combined with oxygen in iron oxide.
- Carbon is more reactive than iron so iron can be extracted using carbon to remove the oxygen from the iron (lll) oxide in the ore. This can be done in a blast furnace.
- Iron (lll) oxide + carbon → iron + carbon dioxide.
- The main impurity in iron is carbon, making the iron very brittle.
- When the iron is molten it can be run into moulds and cast into different shapes. This is called cast iron.
- Removing all impurities from cast iron gives pure iron which is soft and easily shaped.
- A metal that is mixed with other elements is called an alloy.
- Steel is an alloy of iron.
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- Steel is not a single substance, like all other alloys, it is a mixture.
- There are lots of different types of steel, all of which are alloys with carbon and/or other elements.
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- Carbon steels are the simplest steels made by removing most of the carbon from cast iron and leaving just small amounts of carbon.
- These are the cheapest types of steel to make.
- Carbon steels often have small amounts of other elements in them.
- High carbon steel is strong, whereas low carbon steel is brittle and soft.
- Mild steel is a type of low carbon steel and it contains 0.1% carbon.
- It is very easily pressed into shapes, making it useful in mass production.
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- Alloy steels are more expensive than carbon steels because they contain from 1% to 5% of other metals. Each of these metals produce a steel that is well suited for a particular use.
- High alloy steels are more expensive because they contain a much higher percentage of other metals.
- Stainless steels are chromium- nickel steels.
- These steels do not rust as they have a resistance to corrosion.
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