Aluminum-free ultra-high carbon steel and preparation method thereof

The invention discloses aluminum-free ultra-high carbon steel. The aluminum-free ultra-high carbon steel is composed of the following chemical compositions in percentage by weight, 1.81-2.1% of carbon, 1.0-1.3% of chromium, 0.1-0.2% of silicon, 0.6-0.8% of manganese, 0.05-0.15% of molybdenum and the balance iron. The preparation method of the aluminum-free ultra-high carbon steel includes the steps that the components of the aluminum-free ultra-high carbon steel are smelted and processed in a vacuum furnace according to the weight percentage, and aluminum-free ultra-high carbon steel samples are obtained; and the aluminum-free ultra-high carbon steel is obtained by performing thermal treatment. The aluminum-free ultra-high carbon steel is obtained by controlling the alloy components of the ultra-high carbon steel and thermal treatment technological parameters; and the situation that bulk or net-shaped carbide is re-precipitated after complete austenitizing is avoided, and therefore carbide in material organizations can be refined and evenly distributed in matrixes, coordination of strength and toughness of materials and low energy consumption in the machining process are achieved, and operation is easy and convenient.