Processus d'affinage de l'acier Une épopée industrielle

This chapter examines the historical evolution of steelmaking processes with a focus on quality control and the integration of steel scrap into production. It contrasts the early Bessemer and Thomas converters, characterized by very rapid refining and high energy efficiency, with the subsequent development of the Siemens–Martin open-hearth furnace. While Bessemer and Thomas processes enabled fast mass production, they suffered from limited process control, resulting in variable steel quality and a restricted capacity to consume scrap, despite its growing availability and economic advantages. The chapter analyzes the technical and metallurgical limitations of these converters, particularly regarding precise chemical adjustment and compositional homogeneity. In response to these challenges, the Siemens–Martin open-hearth process is presented as a technological breakthrough inaugurating an “era of control and slowness.” Its regenerative heating mechanism, long processing times (6–10 hours), and repeated sampling enable accurate control of temperature and composition, the use of up to 100% scrap, and the production of homogeneous, high-quality steels. The study highlights how this process dominated global steel production for nearly a century, until the 1960s, and underscores the fundamental trade-off between speed and control in steelmaking. More broadly, the chapter situates these developments within the strategic objective of mastering product quality while maximizing the recycling of metallic resources.