Production method of low-alloy high-strength structural steel plate Q355B

The invention discloses a production method of a low-alloy high-strength structural steel plate Q355B. The technological process comprises the steps of molten iron pretreatment, converter treatment, refining, continuous casting, slab heating, rolling, cooling, hot straightening, finishing and performance inspection. The steel comprises the following chemical components in percentage by mass: 0.20 to 0.23 percent of C, 0.25 to 0.40 percent of Si, 0.50 to 0.60 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.015 percent of S, 0.015 to 0.050 percent of Als, 0.010 to 0.015 percent of Nb and the balance of Fe and inevitable impurities. Through reasonable component design and a rolling process, the produced steel plate is stable in mechanical property, and low-cost production of the Q355B steel plate can be achieved due to the fact that few alloys are adopted. 一种低合金高强度结构钢板Q355B的生产方法，工艺流程为铁水预处理→转炉→精炼→连铸→板坯加热→轧制→冷却→热矫→精整→性能检验。钢的化学组成质量百分比为C=0.20～0.23，Si=0.25～0.40，Mn=0.50～0.60，P≤0.020，S≤