Martin steelworks, Compagnie des Fonderies, Forges et Aciéries de Saint-Étienne

The Martin or Siemens-Martin process produces good quality steel by mixing pig iron and scrap metal. The extremely high temperatures this requires are difficult to achieve, but it is more productive and simpler to work than the Bessemer process. Pierre-Émile Martin, son of an ironmaster in the Allier region, combined the hearth* furnace and the process for reusing hot gases invented by the Siemens brothers. His ‘open-hearth furnace’, tested from 1855 and gradually adopted by glass and steel works, uses hot exhaust gases pumped into chambers containing piles of refractory bricks to heat incoming air and thus greatly economise on fuel. The molten steel is cast into ingots, which are then sent to a rolling mill to be made into construction components and railway tracks. This was one of the industrial processes that ensured the growth of steel production in Lorraine and the Saint-Étienne region.