Method for improving solid solution quantity of P of phosphorus containing high-strength IF steel through rare earth treatment

Abstract

The invention discloses a method for improving the solid solution quantity of P of phosphorus containing high-strength IF steel through rare earth treatment. The method is characterized by comprises the steps that at the treatment last stage of the RH refining procedure, an alloy is added in the RH vacuum treatment process, when circulating is carried out for 5 min after alloying is finished, a rare earth cerium-iron alloy is added, and the Ce content of molten steel reaches 18 ppm. By means of the method, rear earth Ce is added into steel, Ce and active O in steel are combined to have lower gibbs free energy, and CeAlO3, Ce2O2S, Ce2O3 and other rare earth oxide, rare earth aluminate and rare earth oxysulfide can be generated extremely easily; and the rear earth Ce suppresses precipitationof the P element and the Fe(Nb+Ti)P phase, the solid solution quantity of the P element in steel can be effectively increased, the solid solution enhancement effect of the P element in the high-strength IF steel can be improved easily, and therefore the r90 value of the forming performance index can be improved easily, and the phosphorus containing high-strength IF steel has better punching performance.

Description

technical field [0001] The invention relates to the fields of steel rolling and product development, in particular to a method for increasing the P solid solution content of phosphorus-containing high-strength IF steel by rare earth treatment. Background technique [0002] With the development of automobiles in the direction of weight reduction and lightweight, automobile sheets with both high strength and ultra-deep drawing properties have been developed rapidly, and solid solution strengthened IF steel is one of the main directions for the development of high-strength IF steel at home and abroad. Because the strengthening effect of P element is good and the price is low, an appropriate amount of P element is added to IF steel and the ratio of Si and Mn elements is adjusted to improve the strength of the steel plate through solid solution strengthening. The higher the proportion of favorable texture, the higher the value of plastic strain ratio r, the better the stamping pe...

AI Technical Summary

Problems solved by technology

[0003] Phosphorus-containing IF steel mainly uses the solid-solution strengthening effect of phosphorus to improve the strength of the steel, but phosphorus is easily precipitated as FeTiP precipitated phase and segregated at the grain boundary, causing the grain boundary brittleness of the steel. The pinning effect hinders the growth of favorable {111} oriented grains and weakens the strength of the γ texture, which is unfavorable for the r value

In addition, the precipitation of Fe(Ti+Nb)P will also consume the solid-solution P element, which reduces the strength of the strip, and also consumes the Ti element, increasing the interstitial C and N atoms, and impairing the formability of the material.

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