T10 clay tempered steel is a type of high carbon steel commonly used in the production of Japanese swords, particularly katana. It is known for its excellent combination of hardness, durability, and resilience. Here's some information about T10 clay tempered steel:

Composition: T10 steel is a type of tool steel that contains approximately 1.0% carbon, along with other alloying elements such as silicon, manganese, chromium, and vanadium. The specific composition can vary slightly depending on the manufacturer or the desired properties of the steel.

Clay Tempering: Clay tempering is a traditional technique used in Japanese swordmaking to create a sharp, hard edge and a resilient, flexible spine. During the clay tempering process, a layer of clay is applied to the blade before it is heated and then rapidly cooled. The clay layer allows for differential cooling, resulting in a hard, martensitic edge and a softer, tougher back or spine. This differential hardening helps to create the characteristic curve and cutting ability of the katana.

Performance and Characteristics: T10 steel is highly regarded for its toughness and resistance to bending or breaking under impact. It can hold a sharp edge well and is known for its ability to withstand heavy cutting and slicing. The combination of the clay tempering process and the carbon content of T10 steel results in a blade with a hard, sharp edge while maintaining flexibility and resilience.

Appearance: T10 steel blades often exhibit a distinctive hamon, which is the visible line along the edge created during the clay tempering process. The hamon represents the transition between the hardened edge and the softer back of the blade and is often considered an aesthetic feature of Japanese swords.

It's important to note that the quality and performance of a sword depend not only on the type of steel but also on the skill and craftsmanship of the swordsmith. The forging techniques, heat treatment, and overall craftsmanship play significant roles in determining the final quality and performance of a T10 clay tempered steel sword.