Method of manufacturing high-strength hot rolled ribbed steel bar

Abstract

The invention provides a method for manufacturing high-strength hot rolled ribbed steel bars, which comprises steps of feeding steel billets into a heating furnace at a furnace temperature of 1,100-1,200 DEG C, heating the steel billets to 1,000-1,100 DEG C, rough rolling at a rolling speed of 0.8-1.4 m / s for 50-88 s, rolling at a rolling speed of 3.4-5.0 m / s for 48-90 s, and fine rolling at a rolling speed of 6.8-17 m / s for 52-88 s; rapidly cooling under conditions of a cooling water flow rate of 240-410 m3 / h under a cooling water pressure of 1.0-2.0 Mpa for 0.6-2.4 s to obtain rolled steel bars with temperature of 810-900 DEG C, and naturally air-cooling to 220-300 DEG C to obtain fine-grain high-strength ribbed steel bars. The invention can remarkably reduce consumption of micro-alloy element V in steel, thereby facilitating protection of rare mineral resources, further reducing cost of hot rolled ribbed steel bars per ton by 300 RMB / ton, having significant economic benefit, improving the strength of steel bars at the same time, and solving the problems in welding and aging of fine-grain high-strength steel bars.

Description

Technical field: [0001] The invention relates to a method for preparing a hot-rolled ribbed steel bar, in particular to a method for preparing a high-strength hot-rolled ribbed steel bar HRB500, and belongs to the technical field of metal material processing and forming. Background technique [0002] my country's annual construction projects use more than 600 million cubic meters of concrete and consume nearly 25 million tons of steel. 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, in MPa. The higher the grade of the steel bar, the better the quality, and the better the strength, toughness and elongation performance, so it is more bene...

AI Technical Summary

Problems solved by technology

However, the main problems of this process are: 1. In recent years, the country has vigorously promoted the use of HRB400 and above steel bars, gradually replacing the currently widely used HRB335 hot-rolled ribbed steel bars

This move has led to a sharp increase in the price of micro-alloys such as vanadium alloys and ferroniobium, which are necessary for the production of HRB500 grade steel bars according to conventional processes. The production cost is too high, which completely squeezes the profit margin of the enterprise, which is not conducive to improving the competitiveness of the enterprise.

2. The cost of producing HRB500 high-strength steel bars by the conventional microalloying process is relatively high, the production motivation of enterprises is insufficient, and the output cannot be scaled up, so it is not conducive to the promotion and application of HRB500 steel bars, and is contrary to the purpose of the central government to build a harmonious society

3. The reserves of ferroniobium and vanadium-nitrogen alloy mineral resources, which are important national strategic reserves, are very limited. The conventional production process has greatly increased the consumption of micro-alloyed ferroniobium and vanadium-nitrogen alloys, and the reserves of ferroniobium and vanadium-nitrogen alloy mineral resources have declined sharply , not conducive to the protection of rare mineral resources and the ecological environment