Stähle

Stähle are iron–carbon alloys with carbon content typically between 0.02 and 2.0 percent by weight, sometimes with additional alloying elements. They are distinguished from cast iron by lower carbon content and greater ability to be shaped, welded, and heat treated. The term covers a broad range of materials used for structural and functional components.

Classification within the Stähle spectrum is commonly by carbon content or by alloying. By carbon content, they are divided into low-carbon (mild) steels, medium-carbon steels, and high-carbon steels. By alloying, alloy steels add elements such as chromium, nickel, vanadium, or molybdenum to tailor strength, hardness, and toughness. Stainless steels form a distinct subgroup, containing a minimum of about 10.5% chromium and offering corrosion resistance. Tool steels are specially formulated alloy steels designed for cutting, forming, and wear resistance.

Production and treatment involve refining and shaping iron to steel in basic oxygen or electric arc furnaces, followed by rolling or forging. Heat treatments such as annealing, quenching, tempering, and normalization adjust microstructure and properties. The resulting microstructures may include ferrite, cementite (pearlite), bainite, or martensite, depending on composition and processing.

Properties and applications vary widely: steels can combine high strength with ductility, while corrosion resistance ranges from poor in plain carbon steels to excellent in stainless grades. Major uses include construction, automotive, machinery, pipelines, tools, and cutlery. Standards and specifications are published by bodies such as ASTM, EN, and ISO to guide composition, mechanical properties, and testing.