The decision to build an integrated metallurgical plant in Concepción was taken during the presidency of Juan Antonio Ríos in 1946. The ironworks were named ´Compañía de Acero del Pacífico´, also known as CAP and were the largest steel making site in Chile.

The production was inaugurated in 1950 with one blast furnace, a coke plant, an open-hearth shop and a bar mill. The planned annual capacity of the plant was 182,000 tonnes of steel.

But then, on 21 May 1960, a devastating earthquake struck, significantly damaging the town and the works as well. Despite the considerable damage, steel production was resumed after eleven days only.

The second blast furnace was put into operation in 1966.
In 1976 the modern LD converters with a capacity of 90 tonnes replaced the outdated open-hearth furnaces.

In the early 1980s the plant was completely reorganised and new company called "Grupo de Empresas CAP" was formed.

In 1990 the construction of the second coking plant was completed, fully replacing the original one from the 1950s.

In 2008 Danieli supplied a state-of-the-art rolling mill for steel bars and rebars production.

However, on 27 January 2010, another strong earthquake hit Concepcion hard, now paralysing the production for two long months.

In 2013 the hot strip mill was mothballed for low demand.

The final end came in 2024, when the mill could no longer resist massive imports of cheap Chinese steel. The heavy end operations were ceased for on the 15th of September.