340MPa grade cold rolled low alloy high strength steel and manufacturing method thereof

The invention discloses a 340MPa grade cold rolled low alloy high strength steel, comprising the following chemical components by weight: 0.030-0.060Wt% of (C); less than or equal to 0.20Wt% of (Si); 0.075-0.095Wt% of (Mn); less than or equal to 0.015Wt% of (P); less than or equal to 0.015Wt% of (S); 0.015-0.045Wt% of (Als); less than or equal to 0.010Wt% of(Ti, Nb) and balance of trace elements Fe and inevitable. The process is as follows: molten iron smelting in a blast furnace, desulphurization pretreatment of molten iron, molten iron smelting in a converter, refining processing of LF molten iron, CSP thin slab continuous casting and rolling, pickling cold continuous rolling, cover annealing, finishing, and inspection packing warehousing. The 340MPa grade cold rolled low alloy high strength steel is stable in chemical composition and mechanical performance, high in strength, and good in plasticity and toughness and forming property.