Public domain
Bessemer converter (iron into steel), Allegheny Ludlum Steel[e] Corp., Brackenridge, Pa.
From the collection of Library of Congress. Free to download, adapt and use — no permission needed.
Credit lineBessemer converter (iron into steel), Allegheny Ludlum Steel[e] Corp., Brackenridge, Pa.. 1939-01-01. Palmer, Alfred T.. FSA/OWI Color Photographs, Library of Congress. Public domain.