LOW TEMPERATURE AGING AND REPEATED STRAIN AGING IN Ni MARAGING STEELS.

On aging in temperature range from 600 to 800 K, Mo rich zones are formed prior to the precipitation of Ni//3Mo, leading to hardening. These zones transform to Ni//3Mo by the in situ process in the later aging stage. At aging below 720 K, however, this transformation occurs in the over aging stage. Repeated strain aging leads to the acceleration of formation of Mo rich zones, resulting in a rapid increase in tensile strength.