Production method of 1500MPa-grade ultrahigh-strength Zn-Cr composite coating hot-formed steel

The invention discloses a production method of 1500MPa-grade ultrahigh-strength Zn-Cr composite coating hot-formed steel. The production method comprises the following steps: directly rolling ultrahigh-strength hot-formed steel by adopting a medium-thin slab, electroplating a Cr + Zn surface composite coating, electroplating a thin coating Cr before galvanizing, and utilizing the high melting point, corrosion resistance and wear resistance of Cr, the surface oxidation in the hot stamping process can be reduced, the corrosion resistance of the product is improved, and microcrack diffusion can be effectively avoided. The invention provides Zn-Cr composite coating hot-formed steel capable of avoiding micro-cracks in order to solve the problem of micro-cracks existing in zinc-based coating hot-formed steel. A Zn-Cr alloy layer is formed in the hot stamping period by utilizing the characteristic of high melting point of chromium, so that the LME phenomenon of the zinc coating in the hot stamping process is avoided