Economical thin-specification Q355B steel plate and preparation method thereof

The invention discloses an economical thin-specification Q355B steel plate and a preparation method thereof. The economical thin-specification Q355B steel plate comprises the following components of,in percentage by weight, 0.16%-0.19% of C, less than or equal to 0.24% of Si, less than or equal to 0.95% of Mn, 0.020%-0.045% of Al, 0.008%-0.015% of Nb, less than or equal to 0.10% of Cr, less thanor equal to 0.025% of P, less than or equal to 0.008% of S, less than or equal to 0.080% of N and the balance iron and inevitable impurities. The process route comprises the steps of molten iron KR pre-desulfurization, converter smelting, LF refining, soft stirring, slab continuous casting, slab reheating, rough rolling, finish rolling, steel plate rapid cooling, steel plate hot straightening, cooling on a cooling bed, shearing and warehousing. 本申请公开了一种经济型薄规格Q355B钢板及其制备方法，包含的组分及重量百分比为：C 0.16~0.19%，Si≤0.24%，Mn≤0.95%，Al 0.020~0.045%，Nb 0.008~0.015%，Cr≤0.10%，P≤0.025%，S≤0.008%，N≤0.080%，其余为铁及不可避免的杂质元素；工艺路线为：铁水KR预脱硫、转炉冶炼、LF精