Effect of percentage elongation on ductility: In a standard tensile test, how does material ductility change as the percentage elongation decreases?

Introduction / Context:
Ductility is a measure of a material’s ability to undergo significant plastic deformation before fracture. It is commonly quantified by percentage elongation and percentage reduction in area obtained from standard tensile tests.

Given Data / Assumptions:

• Ductility indicators: % elongation and % reduction in area at fracture.
• Comparison at similar gauge lengths and testing standards.

Concept / Approach:
By definition, higher percentage elongation means greater capacity for plastic deformation. Therefore, a decrease in percentage elongation indicates reduced ability to plastically deform before failure, i.e., reduced ductility.

Step-by-Step Solution:

Verification / Alternative check:
Handbooks and materials data sheets consistently associate higher % elongation with ductile behavior (e.g., mild steel) and low % elongation with brittle behavior (e.g., cast iron).

Why Other Options Are Wrong:

• “Increases/remains same” contradict the fundamental definition of ductility.
• “First increases then decreases” implies a non-monotonic relationship not supported for a single material comparison.
• “Undefined” is incorrect; ductility remains definable at all % elongations.

Common Pitfalls:
Comparing values taken with different gauge lengths or test standards; conflating ductility with toughness (energy absorption), which also depends on strength and strain behavior.

Final Answer:
decreases