Austenitic Stainless Steels — Typical Composition A standard austenitic stainless steel grade (the classic 18/8) contains which alloying combination?

Introduction / Context:Austenitic stainless steels (e.g., AISI 304) are the most widely used stainless family due to their corrosion resistance, formability, and toughness. The shorthand “18/8” denotes a characteristic composition that stabilises the austenitic structure at room temperature.

Given Data / Assumptions:

• Austenitic class is intended (not ferritic or martensitic).
• Composition is approximate and representative.
• Carbon is kept low to avoid sensitisation (modern L grades).

Concept / Approach:The classic 18/8 stainless steel contains about 18% chromium and 8% nickel. Chromium provides passive-film corrosion resistance; nickel stabilises austenite and enhances toughness. Minor elements (Mn, Si, N) fine-tune properties, but the 18/8 tag captures the essential chromium–nickel balance for the austenitic structure.

Step-by-Step Solution:Identify austenitic class → requires Ni to stabilise FCC at room temperature.Match the common designation “18/8” → 18% Cr, 8% Ni.Select the option that exactly states this composition.

Verification / Alternative check:Materials datasheets for AISI 304 list Cr ~18% and Ni ~8% nominally, confirming the 18/8 shorthand.

Why Other Options Are Wrong:Reversing Cr and Ni percentages or citing carbon-rich variants does not describe the standard austenitic grade.

Common Pitfalls:Confusing 18/8 (austenitic) with 12% Cr ferritic, or 17% Cr martensitic families; the nickel content is the key differentiator.

Final Answer:18% chromium and 8% nickel