Coating-free hot forming steel and preparation method thereof

The invention discloses plating-free hot forming steel and a preparation method thereof, and the plating-free hot forming steel comprises the following raw materials in percentage by mass: 0.3%-0.45% of C, 0.8%-1.5% of Si, 1.2%-2.5% of Mn, 0.8%-2.4% of Cr, 0.01%-0.02% of Ti, less than or equal to 0.002% of B, 0.05%-0.15% of Ni, less than or equal to 0.3% of Mo, 0.04%-0.1% of Nb, 0.05%-0.20% of Al, less than or equal to 0.02% of P and S, and the balance of Fe and inevitable impurity elements. The tensile strength of the plating-free hot forming steel is greater than or equal to 2000MPa; the yield strength ranges from 1200 MPa to 1400 MPa; the elongation at break is greater than or equal to 10%. 本发明公开了一种免镀层热成形钢及其制备方法，所述免镀层热成形钢，包括如下质量百分比的原料：C：0.3％-0.45％，Si：0.8％-1.5％，Mn：1.2％-2.5％，Cr：0.8％-2.4％，Ti：0.01％-0.02％，B：≤0.002％，Ni：0.05％-0.15％，Mo：≤0.3％，Nb：0.04-0.1％，Al：0.05-0.20％，P、S：≤0.02％，其余为Fe和不可避免的杂质元素。本发明免镀层热成形钢的抗拉强度≧2000MPa；屈服强度为1200-1400MPa；断裂延伸率≧10％。