The invention provides a production method for ultralow-
phosphorus hydroforming steel and relates to the technical field of
metal material
smelting. The production method sequentially comprises the steps of molten iron pretreatment, LD converter
smelting, primary LF refining, slagging-
off treatment, secondary LF refining, VD vacuum treatment and
continuous casting. Specifically, molten iron pretreatment is carried out through a KR method; in the LD converter
smelting link, peroxidation is adopted to steel tapping, the final
phosphorus content is strictly controlled; in the primary LF refininglink, a slagging material is added, primary refining dephosphorization is carried out, so that the
phosphorus content of
molten steel reaches to 0.002%-0.003%; after the phosphorus content is qualified, slagging off is carried out; in the secondary LF refining, component adjustment is mainly carried out, and the purity degree is improved; and in VD vacuum treatment, degassing is carried out, and acasting blank is obtained through
continuous casting. The HIC and SSCC performance of the ultralow-phosphorus
hydroforming steel obtained through the production method can meet requirements of the related standard completely, and the chemical components of a steel plate are stable; the content of harmful chemical components of phosphorus and
sulfur is low; nonmetallic inclusion is controlled well; and the quality of the
casting blank is good.