Rails are long steel materials with a special cross-sectional shape that guide the wheels of railway vehicles and support their load. High strength, wear resistance, and fatigue resistance are required, and the hardness and toughness of the rail head, which is the contact surface with the wheels, are particularly emphasized. In addition to railways, their main applications also include industrial transport equipment such as cranes and conveyors. In the manufacturing process, high-purity steel is first produced, then formed into the specified cross-sectional shape using a dedicated hot rolling mill. Afterwards, their properties are improved through heat treatment, including head hardening, and straightness is ensured by straightening. They are then shipped after drilling for fishplates, flash butt welding for lengthening, and strict quality inspections including ultrasonic flaw detection.