Question

Comparing the stress-strain diagrams of cast iron and aluminum alloy, which statement is true regarding their elastic moduli?

• A. Cast iron and aluminum alloy have approximately the same elastic modulus
• B. Cast iron has a higher elastic modulus than aluminum alloy
• C. Aluminum alloy has a significantly higher elastic modulus than cast iron
• D. The elastic modulus is irrelevant in comparing these two materials

Hint:

Stiffness matters! Cast iron is stiffer than aluminum alloy — and that’s reflected in its higher elastic modulus.

Answer 1

The Correct Option is B

The elastic modulus (also called Young’s modulus) measures a material’s stiffness — i.e., how much it resists deformation under stress.
Comparison Between Cast Iron and Aluminum Alloy:

• Cast iron typically has an elastic modulus of around 100–170 GPa.
• Aluminum alloys generally have a lower modulus, approximately 65–80 GPa.
• This means that, under the same applied stress, aluminum will deform more than cast iron.

Why the Other Options Are Incorrect:

• (A) The elastic moduli of cast iron and aluminum are not approximately the same — there's a significant difference.
• (C) Aluminum alloys have a lower, not higher, elastic modulus compared to cast iron.
• (D) Elastic modulus is a key property in stress-strain analysis — it is very relevant when comparing materials.

Therefore, the correct statement is that cast iron has a higher elastic modulus than aluminum alloy.