In materials engineering, cast iron is known for very high resistance to crushing loads. Which mechanical property of cast iron is characteristically the highest compared with its tensile strength and ductility?

Introduction / Context:
Cast iron is widely used in machine bases, columns, engine blocks, and piping due to its distinctive mechanical property profile. Understanding which property dominates guides proper selection for compressive versus tensile or impact applications.

Given Data / Assumptions:

• Material: gray/white cast iron family.
• Application context: static structural loads.
• Microstructure includes graphite (flakes or nodules) or cementite networks depending on type.

Concept / Approach:
The presence of graphite flakes in gray cast iron acts as internal stress concentrators under tension, lowering tensile strength and ductility. Under compression, however, these features are far less detrimental; the matrix can bear very high compressive loads. Therefore, compressive strength greatly exceeds tensile strength for most cast irons.

Step-by-Step Solution:
1) Identify property set: tensile strength (low to moderate), ductility (low), impact toughness (low), compressive strength (high).2) Relate microstructure to behavior: graphite flakes interrupt continuity, reducing tensile properties; in compression, cracks do not propagate as easily from flake tips.3) Conclude: the highest characteristic property is compressive strength.

Verification / Alternative check:
Handbooks consistently list compressive strength roughly 3–4 times the tensile strength for gray cast irons, confirming the trend and typical design practice of using cast iron under compressive service.

Why Other Options Are Wrong:
Ductility: typically very low for gray cast iron.
Shock resistance / impact toughness: poor due to brittle behavior and graphite flakes.
Resistance to brittleness: cast iron is relatively brittle; this is not its strength.
Impact toughness: again characteristically low.

Common Pitfalls:
Assuming high compressive strength implies equal tensile strength. Also, confusing nodular (ductile) iron behavior with gray cast iron can mislead selection.

Final Answer:
compressive strength