In the debate of which material is stronger, steel generally outperforms aluminum. Steel has a higher tensile strength, which is the measure of a material's ability to withstand tension without breaking. The average tensile strength of steel is around 400 MPa (megapascals), whereas aluminum typically ranges from 200 to 300 MPa. This fundamental difference in tensile strength makes steel more resistant to deformation and failure under load.

Data from the American Iron and Steel Institute (AISI) and the Aluminum Association further support this assertion. According to AISI, the yield strength of steel can range from 350 to 600 MPa, significantly higher than the yield strength of aluminum, which is typically between 80 and 120 MPa. Yield strength is the amount of stress a material can withstand before it begins to deform plastically. Additionally, steel has a higher modulus of elasticity, which is a measure of how much a material deforms under stress. The modulus of elasticity for steel is approximately 200 GPa (gigapascals), compared to aluminum's 70 GPa. This higher modulus of elasticity means steel can withstand greater loads without permanent deformation.

Moreover, steel's strength is not solely determined by its tensile strength but also by its hardness and durability. Steel can be heat-treated to achieve various hardness levels, making it suitable for applications requiring high wear resistance. Aluminum, on the other hand, is softer and more prone to scratching and denting. While aluminum is lighter and has better corrosion resistance, its inherent weaknesses in strength and durability make it less suitable for applications where structural integrity is critical.

In conclusion, steel is generally stronger than aluminum due to its higher tensile strength, yield strength, and modulus of elasticity. These properties make steel the preferred material for many structural and industrial applications where strength and durability are paramount.