Preparing method for producing HRB400E fine-grain rebars

Abstract

The invention relates to the technical field of metallurgical manufacturing, in particular to a preparing method for producing HRB400E fine-grain rebars. The method comprises steps of firstly, electric furnace smelting, wherein charging, slagging, deslagging, molten pool stirring and dephosphorization and desulfuration are carried out, and molten steel is obtained; secondly, external refining, wherein the obtained molten steel is subjected to refining; thirdly, vacuum degassing, wherein vacuum air exhaust is carried out, and casting is carried out to obtain a steel ingot; fourthly, forging, wherein program heating is carried out; and fifthly, heat treatment, wherein the forged forge piece is quenched and tempered in sequence, and before quenching, one-time annealing or normalization is carried out. The obtained product is high in yield strength and tensile strength, the mechanical property is good, the elongation is high, the anti-shock effect is better, and the preparing method is easily industrialized, low in cost and better in application prospect.

Description

technical field [0001] The invention relates to the technical field of metallurgical manufacturing, in particular to a method for preparing fine-grained steel bars for producing HRB400E. Background technique [0002] The volume of concrete used in construction projects in my country is huge every year, and a large amount of steel is consumed. Except for a small amount of prestressed steel wire strands, most of them are steel bars used in concrete. There are three grades of hot-rolled ribbed steel bars in my country: HRB335, HRB400 and HRB500. H, R, and B represent hot rolled (Hot rolled), ribbed (Ribbled), and steel bars (bars), respectively, and 335, 400, and 500 represent steel bars, respectively. The minimum yield strength, the unit is MPa. The higher the grade of the steel bar, the better the quality, and the strength, toughness and elongation will be enhanced accordingly. The promotion of high-strength steel bars will undoubtedly help reduce the amount of steel bars us...

AI Technical Summary

Problems solved by technology

At present, the production of HRB400E high-strength seismic steel bars in the industry mostly adopts micro-alloying and hot-rolling processes. The cost of steel alloys produced by this process is relatively high, which is not conducive to enterprises to reduce costs and increase efficiency.

[0005] In addition, there are still the following problems: the rolling start temperature needs to be above 1070°C, and the heating capacity of the conventional heating furnace is insufficient. In order to increase the furnace temperature, sufficient heating is required, which inevitably reduces the production speed. This effect alone will cause production Efficiency is reduced by 20-30%, and at the same time, it will cause large power consumption and coal consumption indicators. For example, the consumption of blast furnace gas per ton of steel will be less than 500m 3 Left and right, increase rolling cost; the existing formula uses Nb, Cu, V and other elements to achieve composite strengthening, the strength-to-yield ratio and performance stability are not strong, and some strength-to-yield ratios are even close to the lower limit of the national standard, and yielding occasionally occurs during the test Not obvious, the pass rate of some specifications is reduced

However, its mechanical strength has just reached the national standard, which is far from enough for special fields of industrial applications.

[0008] At present, there is no low-cost production method of fine-grained steel bars for HRB400E, and the obtained products have good mechanical strength and elongation

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