C75S steel belt for snap spring and preparation method of C75S steel belt

The invention discloses a C75S steel belt for a clamp spring. The steel belt comprises the following chemical components in percentage by weight: 0.71%-0.79% of C, 0.15%-0.35% of Si, 0.60%-0.90% of Mn, less than or equal to 0.018% of P, less than or equal to 0.025% of S, less than or equal to 0.40% of Cr, less than or equal to 0.10% of Mo and the balance of Fe inevitable impurity elements. Meanwhile, the invention discloses a preparation method of the C75S steel strip. After the components are optimized, the hardness of the quenched and tempered snap spring meets the requirement of 53-58 HRC only by increasing the carbon and manganese alloy under the condition that the cost is slightly increased, a clean steel process is adopted for smelting, and a controlled rolling and controlled cooling process is adopted for rolling, so that the purity is ensured, and the hardness meets the standard requirement of the snap spring. 本发明公开了一种卡簧用C75S钢带，该钢带的化学成分按重量百分比计算为C：0.71％-0.79％，Si：0.15％-0.35％，Mn：0.60％-0.90％，P：≤0.018％，S：≤