In 1913 he joined the Société des Forges et Aciéries du Donetz, and from then on was primarily concerned with the iron and steel industry.

As the war dragged on the country faced huge armaments problems, with all efforts concentrated in the Creusot, Loire and Midi regions.

He also held many directorships in Creusot subsidiaries in France and abroad including iron mines, pipe foundries, heavy and fine steel, shipyards and electrical construction.

[2] Aubrun continued to be involved at the highest levels in the iron and steel industry, which was in great difficulties in France and other countries of Europe.

[4] It was replaced by the Comité d'organisation de la sidérurgie (CORSID – Organizing Committee for the Iron and Steel Industry).

[6] The committee had the task of organizing the wartime steel industry, covering issues such as collecting statistics, setting prices, overseeing manufacturing programs, distributing raw materials, managing labor and regulating competition.

It also had the difficult task of dealing with the German occupying authorities, who constantly demanded output from the French industry.

[2] The French Steel Makers' Association (Chambre syndicale de la Sidérurgie) was reconstituted in December 1944 and Aubrun was appointed president.

[8] In September 1954 Aubrun was asked by the flat steel products company Sollac (Société Lorraine de Laminage Continu) to assume the post of president, replacing Léon Daum, who had been called to serve in the High Authority of the European Coal and Steel Community in Luxembourg.