Within a wide programme launched by Finsider, also known as "Oscar Senigaglia plan" the Company was entrusted with the production of quality special steels. Within this plan, the Company Terni and the United States Steel, established a joined company named TERNINOSS ACCIAI INOSSIDABILI, with seat in Terni, for the cold rolling of the coils produced by "Terni".

At the beginning of the sixties, within a nationalization plan, the electrical, chemical and concrete sectors of the company went over respectively to ENEL, ENI and CEMENTIR.

At the beginning of the seventies, the Company committed to a vast plan of plant revamping and of capacity enlargement.