It was founded in 1915, when the Giovanni Andrea Gregorini steel works in Lovere was incorporated by the Franchi brothers, owners of Franchi Griffin s.a. Its initial capital of 2 million lire grew to 3 million.

The new company soon took over Metallurgica Tempini and the facilities of the former Tubi Mannesman in Dalmine. It founded Acciaierie Elettriche in Forno d'Allione, the Dolomite factory in Marone, a large iron warehouse in Brescia, the Ferriere di Ospitaletto Bresciano, as well as opening new mines and reactivating the old ones in Val Seriana, Val di Scalve, Val d'Allione and Pisogne, modernising them and upgrading the old blast furnaces.

Ambitious works for the Barbellino hydroelectric facility received a new boost and work began on a new hydroelectric plant in Forno d’Allione, which was to supply an additional 30,000 hp. The powerful industrial complex created at that time by Attilio Franchi and his brother Camillo provided work for over 30,000 people, of which 10,000 alone were at the Sant'Eustacchio plant. The factory then came under the technical management of Emilio Franchi and in 1932 changed its name to "Società Anonima Stabilimenti di Sant'Eustacchio già Franchi-Gregorini" following its transfer to the IRI.