1916: After acquiring several acres of land in Bonnières, on the banks of the Seine, the industrialist Louis PIRET began manufacturing steel in packs for the Army in February 1916.

1918: The establishment is renamed Usines Métallurgiques de Saint-Eloi (Steel Factory of Saint Eloi).

1956: Development of a rerolling process for rails that were decommissioned by the French railways, to produce high-adherence ribbed iron bars for reinforced concrete. The product gradually acquired recognition in the French market and abroad under the name "CRELOI" (1957).

1973: As a result of a gradual decrease in the number of rails available for re-processing, some French producers and the Compagnie Française des Ferrailles (CFF) decided to adopt the Italian mini-mill model. The aim was to provide material for the rolling mill using steel produced in the electric furnace.

1976: In February 1976, RIVA Group acquired the majority stake in Iton Seine, absorbing the production plants at Saint-Eloi and pursuing the steel and rolling mill business.

Later on, technological innovations (reheating furnace, in-line rolling mill...) implemented at Iton Seine significantly increased production of both steel and reinforced concrete bars.