Austenitic stainless steels: method to increase hardness and tensile strength For 18-8 (austenitic) stainless steels, which treatment/process effectively raises hardness and tensile strength? Select the best option.

Given

• Austenitic stainless steels are to be strengthened/hardened.

Concept
Austenitic grades (e.g., 304, 316) are not hardenable by conventional quench-and-temper heat treatment. They are strengthened by cold working (work hardening), which increases dislocation density and raises both hardness and tensile strength.

Eliminate options
Normalising, martempering, and full annealing do not increase hardness in austenitic stainless; annealing generally softens and restores ductility.

Note
Option (a) is interpreted as work hardening via cold work (proper mechanism).

Final Answer
Hardening and cold working (work hardening)