Tensile test and ductility comparison: If a specimen of material A shows 60% reduction in area at fracture and an identical specimen of material B shows 40% reduction in area, which material is more ductile?
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AMaterial A is more ductile than material B
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BMaterial B is more ductile than material A
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CBoth materials have equal ductility
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DMaterial A is brittle and material B is ductile
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ENeither material is ductile
Answer
Correct Answer: Material A is more ductile than material B
Explanation
Introduction / Context:Ductility in a tensile test is commonly judged by the percentage reduction in area at fracture and/or percentage elongation. A higher percentage reduction in area indicates that the material can undergo more plastic deformation before failure, hence it is more ductile.
Given Data / Assumptions:
- Specimens of equal initial dimensions are tested in tension.
- Material A: reduction in area = 60%.
- Material B: reduction in area = 40%.
- Standard tensile test conditions and accurate measurements are assumed.
Concept / Approach:Percentage reduction in area is defined as ((A0 − Af) / A0) * 100%, where A0 is original cross-sectional area and Af is area at the fracture section. Larger values imply greater necking and plastic flow ability, which correspond to higher ductility.
Step-by-Step Solution:
Compute ductility metric: %RA_A = 60%, %RA_B = 40%.Compare: 60% > 40%.Inference: The material with the higher % reduction in area is more ductile.Conclusion: Material A is more ductile than material B.Verification / Alternative check:One may also check percentage elongation. Typically, a material with higher % reduction in area also shows higher % elongation, reaffirming the same conclusion about ductility ranking.
Why Other Options Are Wrong:
- Material B more ductile: contradicts 40% vs 60% comparison.
- Equal ductility: data clearly differ.
- “A is brittle and B is ductile”: opposite of the evidence.
- “Neither material is ductile”: reduction in area values indicate plasticity in both.
Common Pitfalls:Confusing strength with ductility; using ultimate tensile strength alone to judge ductility; ignoring measurement consistency in necked area readings.
Final Answer:Material A is more ductile than material B