Real katanas, particularly those made using traditional Japanese sword-making methods, are typically made from specialized steel known as tamahagane. Tamahagane is a specific type of steel that is produced through a traditional smelting process unique to Japan.

Tamahagane steel is created by smelting iron sand and charcoal in a traditional clay furnace called a tatara. The process involves multiple stages of heating, melting, and refining to extract and purify the iron. This results in a steel with a high carbon content and a varied, layered structure that provides both strength and flexibility.

The tamahagane steel is then forged into a blade by a skilled swordsmith. The process includes heating, hammering, and shaping the steel to create the desired blade profile and edge geometry. After the shaping process, the blade undergoes heat treatment, which involves quenching and tempering to enhance its hardness, resilience, and edge retention.

It's worth noting that while traditional tamahagane steel is highly regarded for its historical significance and authenticity, modern sword-making techniques may also utilize other types of steel with specific properties and characteristics. Different types of high-carbon steel, such as 1060, 1095, or 9260, are commonly used in the production of functional katanas today.

The choice of steel depends on factors such as the intended use of the sword, the desired balance between hardness and flexibility, and the preferences of the swordsmith and the client. Regardless of the specific type of steel used, the craftsmanship and expertise of the swordsmith in forging and tempering the blade play a crucial role in creating a high-quality katana.