What is the effect of adding 1% of carbon to a steel alloy?

Adding about 1% of carbon to a steel alloy generally leads to an increase in strength while simultaneously reducing ductility. Carbon acts as a strengthening agent in steel because it allows for solid solution strengthening and the formation of various microstructures such as pearlite, which contributes to the hardness and strength of the material.

Lower ductility occurs because the carbon atoms interfere with the movement of dislocations within the steel's microstructure. As the carbon content increases, steel becomes stronger (due to hardening effects) but also becomes less able to deform easily under stress. This interplay between strength and ductility is critical in structural applications where high strength is essential, but sufficient ductility is also required to accommodate loads without failure.

In summary, the addition of carbon effectively enhances the hardness and tensile strength of steel, creating a material that is more suitable for applications demanding high mechanical properties, albeit at the cost of some ductility.