On the Strain Hardening Stability of Initially Isotropic Metallic Materials under Natural Ageing

The strain hardening stability of initially isotropic structurally stable metallic materials under natural ageing is studied experimentally. Martensitic steel and titanium and aluminum–magnesium alloys, which harden in accordance with the isotropic–kinematic hypothesis, are used as an example to show that the shape of the loading surface does not change during ageing and its size and position may vary with time