Corrosion-resisting rebar with yield strength in 500 MPa grade and production method

Abstract

The invention discloses a corrosion-resisting rebar with the yield strength in 500 MPa grade and a production method, and belongs to the technical field of corrosion-resisting steel for construction.The rebar comprises, by weight, the chemical components including 0.05-0.10% of C, 0.30-0.60% of Si, 1.20-1.50% of Mn, 1.00-1.50% of Cr, 0.10-0.20% of Ni, 0.20-0.40% of Cu, 0.10-0.20% of Mo, 0.06-0.10% of V, 0.010-0.025% of Ti, 0.035% or less of P, 0.010% or less of S and the balance Fe and inevitable residual impurity elements. According to the rebar, by adding small amounts of the alloying elements and fully using each individual element and the synergistic action among the elements, the corrosion resistance performance of the rebar is improved; the production method of the rebar comprises the steps of conventional smelting and casting and adoption of a controlled rolling and controlled cooling technology on a bar mill; noble metal elements in the rebar are low in contents, the toughness, the weldability and the corrosion resistance performance of the rebar are excellent, resources are saved, and the production cost is low.

Description

Technical field: [0001] The invention belongs to the technical field of corrosion-resistant steel for construction, and in particular relates to a corrosion-resistant steel bar with a yield strength of 500 MPa and a manufacturing method thereof. Background technique: [0002] Cases of premature failure of concrete structures due to chloride ion erosion in marine environments are widespread, resulting in huge economic losses. At present, with the vigorous development of the South China Sea, the service environment of the South my country Sea, such as high temperature, high humidity, high salt, and roads using deicing salts, has put forward higher requirements for the durability of reinforced concrete structures. The corrosion of steel bars not only greatly shortens the overall life of the building, but also poses a safety hazard. The use of corrosion-resistant steel bars is the last line of defense against premature failure of reinforced concrete structures due to steel bar ...

AI Technical Summary

Problems solved by technology

In practice, it is found that the coating film of coated steel bars is often severely damaged during transportation, handling, binding and concrete pouring construction, and the pitting corrosion of steel bars will be more serious, which will lead to a decline in the overall durability of reinforced concrete.

FRB bars also have obvious deficiencies, which are mainly reflected in poor bonding strength with concrete, low shear strength, low elastic modulus, and poor thermal stability. It is difficult to apply in high-strength concrete structures; The durability of the FRP material itself will largely affect the durability of the FRP reinforced concrete structure in environments such as alkali, acid, and salt.

Stainless steel bars contain a large amount of valuable Cr, Ni and other alloying elements, making their production costs significantly higher than ordinary carbon steel bars. The one-time investment cost of projects using stainless steel bars is about 4-6 times that of ordinary carbon steel bars of the same level, which is larger The application of stainless steel bars in concrete structures is limited to a certain extent

[0004] Chinese patent CN103834871A discloses a 500MPa level corrosion-resistant Cr-containing steel bar and its rolling process. Although the steel bar is corroded by salt spray in 5% NaCl solution, its corrosion resistance is 4 to 6 times that of ordinary HRB500 steel bar, but in the steel bar Containing 8-10% Cr, the alloy elements are high, the cost is high, and it is not conducive to resource conservation; at the same time, such a high Cr content and low C content, the existing steel smelting process is difficult to meet the requirements, and the Cr element is hardened Such a high Cr content will form a martensitic structure even if it is slowly cooled, and it is difficult to meet the requirements of the conventional steel bar production process.

Chinese patent document CN106756518A discloses a 500MPa-grade corrosion-resistant steel bar and its production method. The chemical components in the steel bar are: C: 0.16-0.20%, Si: 0.30-0.50%, Mn: 1.10-1.30%, V: 0.07~0.09%, S≤0.03%, P≤0.03%, Cu: 0.30~0.40%, Cr: 0.8~1.0%, although the steel alloy cost is low, but the steel is not added to inhibit the cracking of Cu on the surface The element Ni is easy to form cracks on the surface of the slab, which affects the quality and corrosion resistance of the product; in addition, the C element is relatively high and the Cr content is low, and localized corrosion (pitting defects, etc.) is prone to occur under the conditions of wet and dry immersion corrosion

Chinese patent document CN105950989A discloses a corrosion-resistant steel bar and its production method. The chemical composition of the steel bar is: C: 0.15-0.23%, Si: 0.30-0.65%, Mn: 0.90-1.60%, P≤0.03%, S≤ 0.03%, Cr: 1.40-2.50%, Cu: 0.20-0.40%, Ti: 0.010-0.025%, N≤0.015%, O≤0.0020%, the element Ni that inhibits Cu from cracking on the surface is not added to the steel bar, Cracks are easy to form on the surface of the slab, which affects the quality and corrosion resistance of the product; due to the high N content in the steel bar, Ti first combines with Ti to form TiN particles at high temperature, so limited Ti is used to inhibit the combination of Cr and C, thereby inhibiting pitting corrosion The phenomenon ability is limited, and its pitting and localized corrosion are unavoidable

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