Why do we use steel instead of just normal iron or aluminum or something?
In: Engineering
“Stronger” is a nebulus term. Do you want strength in relation to mass, or absolute strength? Do you want tensile strength, compressive strength, shear strength? All these properties differ from metal to metal.
However, why is steel stronger than wrought iron, for example? It’s all to do with the [crystal structure](https://www.lff-group.com/posts/carbon-steel-fundamentals-part-1#:~:text=Carbon%20steel%20is%20fundamentally%20an%20alloy%20of%20iron%20and%20carbon.&text=Below%200.008%20wt%25%2C%20the%20structure,the%20centre%20(Figure%201).) of the metals. In basic terms, every so often in your steel, you hit a “wall” of carbon, which keeps the iron from shifting and moving about, making the steel harder.
The same is true of steel-vs-aluminum, the crystal structures of steel is better at staying static with tensile stresses (about 5x better), so in cases where your part is under tension, and weight is not an issue, we will use steel over aluminum.
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