Included in the document files on BOF (basic-oxygen) or LD-process steelmaking is information on its history, the patents covering the process, its physical chemistry, its worldwide growth and development, world capacity by countries, the controversy surrounding its early use, its diffusion in the United States and Japan, its application in steel foundries, LD and LD-AC comparisons with other processes, AISI operating data for BOF facilities in the United States during selected years from 1959 to 2000, and descriptions of BOF steel operations at Alan Wood Steel Company, the Aliquippa plant of Jones & Laughlin Steel Corporation, the Bethlehem plant of Bethlehem Steel Corporation, Ford Motor Company, and Pittsburgh Steel Company. The files provide capacity and other information compiled by noted LD historian, Joseph K. Stone, and the Archive’s book collection contains Oxygen Steelmaking from the Association of Iron and Steel Engineers (AISE).
Analysis: The basic-oxygen furnace (BOF) for steel production unquestionably was one of the leading technological breakthroughs in the steel industry during the twentieth century. Upon its introduction in the 1950’s, the new method revolutionized integrated steel operations by cutting the time required from an average of 9-10 hours in then normal open-hearth steel production to some 45 minutes, and it appreciably reduced investment and operating costs as well.
Basic-oxygen steelmaking was developed in Austria after World War II by two companies, Voest, located in Linz , and Alpine-Montan in Donawitz, accounting for the process designation LD. The two companies commercialized the process in 1952, and it since has been adopted throughout the world and has come to be commonly designated the basic-oxygen furnace or BOF process.
In the BOF process, an open-topped, pear-shaped converter is tilted on side-mounted trunnions to receive a charge of scrap and hot metal, before being returned to an upright position. Next, a top-mounted oxygen lance is lowered into the converter to within some six feet of the charge, and about 45 cubic meters of pure oxygen is blown in for each ton of steel produced. Once the lance is withdrawn, the converter is again tilted to pour the heat of molten steel into a ladle. Among various process modifications have been the LDAC, which injects lime along with oxygen to refine high-phosphorous iron; the LWS, Q-BOP, and OBM, in which oxygen is blown through the bottom of the converter; and KMS, which employs both top and bottom blowing.
The first BOF converters produced less than 70 tons per heat, which initially limited the technology’s adoption within large, multi-million-ton plants. However, the process was rapidly scaled up, and by the early 1960’s was capable of producing more than 290 tons per heat. Adoption of the BOF thereafter was made possible by the steady availability of commercially pure oxygen at suitable costs, its displacement of the open-hearth coinciding with and being accelerated by the introduction of another breakthrough technology, continuous casting.
The continuous slab casters that integrated mills installed required the delivery of liquid steel at much shorter cycle times than the much slower open-hearth could attain, and so the BOF and continuous casting complemented one another in making the entire process of producing semifinished steel much more efficient and continuous. In so doing, the BOF share of world crude steel output increased from less than 10% in 1960 to 60% at the end of the twentieth century.