Low carbon steel is softer and more easily shaped.

The idea

Low carbon steel contains only a small proportion of carbon in its iron alloy. With fewer carbon atoms disrupting the structure, the layers of iron atoms can slide over one another more readily when a force is applied. This makes the steel softer and more malleable, so it can be bent, pressed or rolled into shape without cracking. It is therefore useful for applications such as car bodies, nails, wire and structural beams, where the material must be shaped or withstand bending rather than hold a sharp cutting edge. The contrast with high carbon steel shows how carbon content controls properties.

What earns the marks

• State that low carbon steel contains a relatively small proportion of carbon in the iron alloy.
• Explain that fewer carbon atoms allow the layers of iron atoms to slide over one another.
• Link the sliding layers to softness and to being easily shaped, bent or pressed.
• Compare low carbon steel with high carbon steel, noting that lower carbon content gives greater flexibility and less brittleness.
• Apply the properties to a suitable use, such as car bodies, wire or structural beams.

Common mistakes and how to put them right

• Saying low carbon steel is weak because it is soft.

  Put it right by explaining that softness means it deforms easily, while it can still be strong in use.

• Claiming low carbon steel is brittle.

  Put it right by stating that it is more easily shaped and less likely to crack than high carbon steel.

• Ignoring the role of carbon content.

  Put it right by linking the small amount of carbon to the ability of layers to slide.

Exam tips

• Compare low carbon steel directly with high carbon steel to show the effect of carbon content.
• Use terms such as malleable, ductile or easily shaped accurately when describing the property.
• Link the property to a named use, such as car body panels that must be pressed into shape.