Corrosion protection – Meaning of galvanised iron: In everyday engineering practice, “galvanised iron” (GI) primarily implies that the steel/iron surface has been treated to achieve which outcome?

Introduction / Context:
Galvanising is the process of applying a protective zinc coating to steel or iron, primarily to prevent corrosion. GI sheets, pipes, and fittings are ubiquitous in construction, utilities, and consumer products because the zinc layer provides both barrier protection and sacrificial (cathodic) protection.

Given Data / Assumptions:

• Hot-dip galvanising or electro-galvanising is used.
• Service environment exposes the metal to moisture and oxygen.

Concept / Approach:
Zinc is more anodic than iron/steel. When a galvanized surface is scratched, zinc preferentially corrodes (sacrificial anode), protecting the exposed steel. In addition, tightly adherent zinc corrosion products slow further attack, providing barrier protection. The main purpose of galvanising is therefore corrosion protection, not hardening.

Step-by-Step Solution:
Identify galvanising as zinc coating.Relate zinc's electrochemical role to sacrificial protection of steel.Conclude that the outcome is enhanced resistance to rusting.

Verification / Alternative check:
Field performance of GI in atmospheric exposure demonstrates prolonged service life versus bare steel, especially when coating thickness is adequate.

Why Other Options Are Wrong:

• Hardness increase is not the target property; any change is incidental.
• Alumina coating is not what “galvanized” means; that would be an entirely different surface treatment.
• “None of these” is incorrect since corrosion protection is the explicit goal.

Common Pitfalls:
Assuming galvanising fixes all corrosion issues; severe or chloride-rich environments may still require duplex coatings (zinc + paint) or stainless steels.

Final Answer:
It is protected from rusting (zinc-coated)