Aging and partial austenitizing of age-hardenable CrNiMo steels of the type 10-10-2 and 6-11-3

The effect of aging and partial austenitizing on the structure, mechanical properties and resistance to corrosion has been investigated in two types of age-hardenable martensitic-austenitic CrNiMo steels alloyed with titanium and aluminium.

Among the fundamental characteristics examined for these steels particular attention has been paid to metallurgical cleanness. The precipitation strengthening is caused by dispersed phases, in particular Ni₃ (Al, Ti)-γ′. During gradual overaging stabilized austenite forms on martensitic interfaces. Partial austenitizing treatment slightly above A_s produces the maximum austenite content.

Overaged 10Cr10Ni2Mo (wt.%) steel achieves superior strength coupled with a favourable level of toughness and corrosion resistance compared with CrNiMo steels of the types 13-4-1 and 15-6-1.