| abstract |
The invention discloses an economical 690MPa grade high-strength steel sheet and a preparation method thereof. The high-strength steel sheet comprises the following chemical components by mass fraction: C: 0.17%-0.20%, Si: 0.25-0.40%, Mn: 1.35%- 1.50%, P≤0.020%, S≤0.015%, Als: 0.020～0.040%, Cr: 0.20%～0.30%, Nb: 0.010%～0.020%, Ti: 0.015～0.025%, B: 0.0015～0.0025%, The rest are Fe and inevitable impurities; and Mn+Cr≥1.60%, CEV=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15≤0.50%; the present invention is economical The yield strength of the high-strength steel plate is ≥690Mpa, the tensile strength range is 770～900MPa, the elongation after fracture is ≥15%, and the Charpy impact energy (longitudinal) KV 2 at ‑20℃ is ≥80J. The steel plate has good welding performance and is suitable for the market. Production of high-strength structural steel parts for most construction machinery that are not required for special purposes. |