Stainless steels — martensitic family identification: A steel containing about 12 to 14% chromium and 0.12 to 0.35% carbon is classified as which stainless steel type?

Introduction / Context:
Stainless steels are grouped by structure and composition: martensitic, ferritic, austenitic, duplex, and precipitation-hardening. Chromium around 12 to 14% with moderate carbon is characteristic of martensitic grades used for cutlery, turbine blades, and wear-resistant parts.

Given Data / Assumptions:

• Chromium content: ~12 to 14%.
• Carbon content: ~0.12 to 0.35% (hardenable range).
• Heat treatability by quenching and tempering is intended.

Concept / Approach:
Martensitic stainless steels are hardenable due to sufficient carbon and display a body-centred tetragonal martensitic structure after quench. Ferritic grades have similar chromium but very low carbon and are not hardenable by quench. Austenitic grades require higher nickel to stabilise the face-centred cubic structure and usually contain 16 to 20% chromium plus 8 to 10% nickel. Duplex and precipitation-hardening grades have different composition balances.

Step-by-Step Solution:
Match composition window: 12–14% Cr with 0.12–0.35% C.Recognize hardenability and martensitic transformation potential.Select the family that fits: martensitic stainless steel.Confirm that other families require different alloy balances.

Verification / Alternative check:
Examples include types similar to 410/420 families that fit this Cr–C window and are quench-and-temper hardenable.

Why Other Options Are Wrong:
Austenitic needs high Ni and higher Cr; ferritic has very low carbon; duplex blends ferrite and austenite with notable Ni and Mo; P.H. grades rely on age-hardening precipitates and different compositions.

Common Pitfalls:
Assuming all stainless steels are non-magnetic (martensitic and ferritic can be magnetic) or equating stainless solely with high nickel content.

Final Answer:
martensitic stainless steel