Steel is made from iron ore and is a general term for metallic materials, which the main components are iron (Fe) and carbon (C). In general, the higher the carbon content, the stronger the steel tends to be. Extremely pure iron is not suitable for industrial products because it is brittle and easily participates. Steel is an alloy made by intentionally increasing the amount of carbon in iron, and what is commonly referred to as iron, is said to refer to steel. Steel is a commonly used alloy because it has superior strength and toughness compared to iron and is easy to process. There are two typical types of steel: SS material and S-C carbon steel material. SS material is officially called rolled steel for general structural use, which is focused on tensile strength and tenacity. Carbon steel S-C series is officially called carbon steel for machine structural use, which focuses on hardness and strength.