Stainless steel grades — meaning of 18/8: 18% chromium and 8% nickel composition corresponds to which stainless steel family?

Introduction / Context:
The shorthand “18/8” denotes 18% Cr and 8% Ni, the archetype of widely used stainless steels for food processing equipment, chemical plant, and general service.

Given Data / Assumptions:

• Composition: ~18% chromium, ~8% nickel, balance iron.
• Common examples: AISI 304/304L variations.
• Applications demand corrosion resistance and formability.

Concept / Approach:
Nickel stabilizes austenite at room temperature in Fe–Cr–Ni alloys. With 18% Cr for passivity and 8% Ni for austenite stabilization, the steel falls squarely in the austenitic family, featuring non-magnetic behavior (annealed), good weldability, and excellent corrosion resistance in many environments.

Step-by-Step Solution:
Match composition with family definitions.Recognize AISI 304 as the standard 18/8 alloy.Select “austenitic stainless steel.”

Verification / Alternative check:
Materials standards and vendor datasheets classify 18/8 as 300-series, austenitic grades.

Why Other Options Are Wrong:
Ferritic/martensitic: lower or zero nickel; microstructure not austenitic at room temperature.

Common Pitfalls:
Assuming all stainless steels are magnetic; austenitic types are generally non-magnetic in annealed state.

Final Answer:
Austenitic stainless steel