Automobile beam steel with tensile strength of 610MPa and preparation method for automobile beam steel

The invention provides automobile beam steel with tensile strength of 610MPa and a preparation method for the automobile beam steel. The automobile beam steel comprises the following chemical components in percentage by mass: 0.04-0.12% of C, 0.05-0.35% of Si, 0.8-1.4% of Mn, less than and equal to 0.015% of S, less than and equal to 0.02% of P, 0.02-0.05% of Als, 0.04-0.08% of Ti, and the balance of Fe and inevitable impurities. The tissue of the automobile beam steel is quasi-polygonal ferrite and bainite, wherein the volume fraction of the quasi-polygonal ferrite is 85-95%, the volume fraction of the bainite is 5-15%, and the mean grain size is 3-6 microns. The invention further provides a preparation method for the automobile beam steel. A steel billet adopting the chemical component proportion is subjected to a reasonable process design, cheap micro alloy titanium is used to replace precious micro alloy niobium and vanadium, the production cost is reduced while load of a rolling mill and a reeling machine is reduced, the production efficiency is improved, and the automobile beam steel with tensile strength of 630 MPa to 690 MPa is obtained.