Why do age hardening curves often show a peak strengthSoluti

Why do age hardening curves often show a peak strength?

Solution

In Precipitation hardening, the precipitates are effective in hindering dislocation motion which in turn, increases alloy hardness and strength. As the aging takes place, the strength reaches a peak value and then decreases due to overageing. Strength is sensitive to aging time. Higher the aging temperature, lower will be the peak strength and vice-versa. For peak strengthening, optimum size and distribution of precipitate is required.