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Difficulty: MediumAlloys: Classification, Compositions, Physical Properties, and Uses

Stainless steel exhibits high resistance to atmospheric corrosion primarily because incorporated chromium reacts with oxygen to form a micro-thin, passive oxide surface layer that prevents further oxidation of the underlying iron.

Answer: Answer

Answer

The statement is TRUE. The addition of chromium to iron in stainless steel leads to the formation of an adherent, passive chromium(III) oxide (Cr2O3Cr_2O_3) film on the surface, protecting the alloy from ongoing oxidation.
Chromium in stainless steel reacts with ambient oxygen to generate a thin, self-repairing surface film of Cr2O3Cr_2O_3. This passive layer serves as a barrier preventing moisture and oxygen from coming into direct contact with the iron matrix, stopping corrosion.

Step-by-Step Solution

1
Identify the primary alloying constituent responsible for corrosion resistance in stainless steel.
Stainless steel is an alloy composed of iron (FeFe), carbon (CC), chromium (CrCr), and often nickel (NiNi). Chromium is the element specifically added to impart corrosion resistance.
Understanding the chemical roles of individual constituent metals in an alloy is necessary to evaluate physical and chemical property modifications.
2
Analyze the surface chemical reaction between chromium in the alloy and atmospheric oxygen.
Chromium oxidizes preferentially over iron to form a continuous, insoluble layer of chromium oxide (Cr2O3Cr_2O_3).
This process, known as passivation, prevents reactive agents like water and oxygen from penetrating to the core iron atoms.
3
Evaluate the correctness of the statement based on passivation principles.
The statement accurately describes the passivation process of stainless steel.
Because chromium passivation is the accepted scientific mechanism for stainless steel's rust prevention, the statement is true.

Key Concept

Passivation and Corrosion Resistance of Chromium in Steel Alloys
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Topics

Alloys: Classification, Compositions, Physical Properties, and Uses

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