Flat spring steel and manufacturing process thereof

The invention discloses flat spring steel and a manufacturing process thereof. The flat spring steel comprises the following chemical components in percentage by weight: 0.38-0.62 wt% of C, 0.40-1.20wt% of Si, 0.70-1.30 wt% of Mn, less than or equal to 0.025 wt% of P, less than or equal to 0.025 wt% of S, 0.80-1.25 wt% of Cr, 0.08-0.35 wt% of V, 0.01-0.05 wt% of Nb, 0.001-0.004 wt% of B, 0-0.006wt% of Zr, and the balance of Fe and inevitable impurities. The performances of the flat spring steel meet the requirements that ReL is larger than or equal to 1480 MPa, Rm is larger than or equal to1700 MPa, A is larger than or equal to 8%, and Z is larger than or equal to 35%; the through hardening performance J25 is larger than or equal to 56 HRC; and under the condition that the maximum design stress of a steel plate made of the flat spring steel is 1050 MPa, the fatigue life is 12 ten thousand times or above. 本发明公开了一种弹簧扁钢及其制造工艺，其化学成分按重量百分比计为，C：0.38～0.62wt％、Si：0.40～1.20wt％、Mn：0.70～1.30wt％、P≤0.025wt％、S≤0.025wt％、Cr：0