Failure behaviour — tensile loading of brittle materials When brittle materials are subjected to tensile loads, they typically fail by snapping without any significant plastic elongation. Is this statement correct?

Difficulty: Easy

Correct Answer: Yes

Explanation:


Introduction / Context:
Brittleness and ductility describe how materials behave near fracture. Understanding these differences is vital for safe design, material selection, and failure analysis under tensile loading.



Given Data / Assumptions:

  • Brittle materials (e.g., glass, ceramics, some cast irons) show little or no plastic deformation before fracture in tension.
  • Standard tensile testing conditions at room temperature.



Concept / Approach:
Brittle fracture occurs with minimal prior plastic flow; cracks propagate rapidly once initiated, often along cleavage planes or flaws. The stress–strain response shows a near-linear portion until catastrophic break, unlike ductile metals that display yielding and necking with noticeable elongation before fracture.



Step-by-Step Solution:
Define brittleness: low capacity for plastic deformation under tensile stress.Relate to tensile test observations: negligible uniform elongation, sudden fracture.Conclude that the statement is correct for classic brittle materials.



Verification / Alternative check:
Fractography of brittle materials reveals shiny, granular, or mirror/mist/hackle regions without ductile dimples. Engineering handbooks distinguish brittle from ductile failure modes precisely on elongation at break.



Why Other Options Are Wrong:

  • No: contradicts the defining trait of brittleness.
  • Only at very low temperatures: while low temperature can embrittle some metals, intrinsic brittle materials are brittle at room temperature too.
  • Only in compression: brittle materials often tolerate higher compressive than tensile strains; the statement concerns tension.
  • Depends solely on surface finish: surface defects matter but do not define brittleness.



Common Pitfalls:
Assuming all metals are ductile; some alloys (e.g., white cast iron) behave in a brittle manner under tension.



Final Answer:
Yes

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