A kind of steel for reinforcing bar and production method thereof

Abstract

The invention relates to steel for a rebar and a production method thereof. The steel comprises the following proportioned chemical components in percentage by weight: 0.18-0.25% of C, 0.30-0.70% of Si, 1.20-1.60% of Mn, at most 0.035% of P, at most 0.035% of S, 0.03-0.06% of V, 0.008-0.012% of N, 0.01-0.06% of Als, and the balance of Fe and unavoidable impurities. The production method comprises the following steps of: (1) smelting according to the proportion and number of components; (2) refining; (3) carrying out billet continuous casting; (4) rolling by a bar mill; (5) cooling. Room-temperature mechanical properties of the steel meet the following conditions: the yield strength ReL is not less than 400MPa, the tensile strength Rm is not less than 540MPa, the ratio of tensile strength and yield strength is not less than 1.25, the fracture elongation percentage A is not less than 15%, and the even percentage elongation Agt is not less than 9%; and the steel has good surface quality, and has no surface defects, such as cracks.

Description

technical field [0001] The invention relates to steel for hot-rolled ribbed steel bars for reinforced concrete and a production method thereof, in particular to a steel for large-scale high-strength steel bars with a diameter not less than φ36mm and a production process for its surface without defects. Background technique [0002] The hot-rolled ribbed steel bar is the skeleton material of the concrete structure and carries various stresses in the structure. In recent years, with the emergence of a large number of high-rise, long-span, earthquake-resistant, low-temperature-resistant, and fire-resistant building structures in China, the steel bars have developed in the direction of large diameter, high strength, high toughness, and good weldability. The demand for specification steel bars is increasing day by day. Compared with ordinary specifications (≤φ32mm), large-scale high-strength steel bars have higher safety performance and are mainly used in various national key en...

AI Technical Summary

Problems solved by technology

The disadvantage is that the N content is too high, which will easily lead to defects such as subcutaneous air bubbles in the slab, and affect the plasticity index and surface quality of the steel bar.

The disadvantage is that B tends to promote temper brittleness, and when the B content exceeds 0.007%, it will cause hot embrittlement of steel and affect hot workability

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