400 MPa-level Cl environment corrosion resistant steel bar and manufacturing method thereof

Abstract

The invention discloses a 400 MPa-level Cl environment corrosion resistant steel bar and a manufacturing method thereof and belongs to the technical field of corrosion resistant steel for building. The chemical components of the steel bar comprise, by weight, 0.08-0.12% of C, 0.40-0.70% of Si, 1.00-1.30% of Mn, 1.00-1.30% of Cr, smaller than or equal to 0.20% of Ni, 0.20-0.40% of Cu, 0.10-0.20% ofMo, 0.04-0.07% of V, 0.02-0.04% of Nb, smaller than or equal to 0.035% of P, smaller than or equal to 0.010% of S, and the balance Fe and inevitable remaining impurity elements. According to the method, by means of the synergistic effect of the alloy elements, corrosion resistant performance of the steel bar is improved, and different reinforcing mechanisms of the alloy elements are utilized forcarrying out the comprehensive strengthening and toughening design. According to the manufacturing method of the steel bar, smelting and pouring are carried out by the book, and then the controlled rolling and controlled cooling technology is adopted on a bar mill. The content of precious metal elements in the steel bar is small, the comprehensive performance of the steel bar is 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, in particular to a 400MPa class Cl-resistant steel - Environmental corrosion of rebar and methods of manufacture. Background technique: [0002] Steel bars are the basic materials of modern buildings, widely used in the construction of houses, bridges, roads, etc., and their performance directly affects the life and safety of concrete components. No matter in foreign countries or at home, steel bar corrosion is the most important and common disease that threatens the durability of reinforced concrete structures. The direct and indirect losses it causes are far beyond people's expectations. Although concrete has a protective effect on steel bars, in actual application, especially in Cl - When used in a corrosive environment, steel bars are easily corroded, which reduces the service life of the building structure, brings huge losses to the national economy, and...

AI Technical Summary

Problems solved by technology

However, there are some problems in practical application: the addition of steel rust inhibitor when mixing concrete will reduce the strength of concrete; the epoxy resin coating will age after 5 years, lose its protective effect, and be easily damaged during transportation and implementation coating, the damaged part will intensify local corrosion; the galvanized coating on the surface will also be corroded after a period of use, and the high Cl - Under high concentration conditions, galvanized steel bars are easy to delaminate, which accelerates the corrosion of steel bars; stainless steel bars are added with a large amount of alloying elements Cr and Ni, and the Cr content is generally not less than 12%. The production cost is high and it is difficult to popularize and use it in large quantities.

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Chinese patent document CN103789677A discloses a high-strength steel bar with high corrosion resistance and a preparation method thereof. Although the steel bar has high strength and corrosion performance, the steel bar contains 7-9% Cr, 1.5-4.0% Ni, Al, and Cu alloys have a high content of alloying elements, which are close to the composition of stainless steel bars, resulting in waste of resources, high cost, and poor welding performance; at the same time, the existing steel bar production process produces its structure that is easy to form martensite or bainite. Tensile body, resulting in excessive strength, its strength is much higher than the existing widely used IV and V grade steel bars, which is not conducive to widespread promotion

Chinese patent document CN107034418A discloses a 400MPa grade chlorine ion corrosion-resistant high-strength steel bar for concrete and its production method. Modification to improve its corrosion performance, but the Cr content in the alloy is relatively low, and Cr is easy to combine with C to form fine carbides when cooling in the cooling bed during the production process, resulting in local chromium deficiency and pitting corrosion

Chinese patent document CN104109815A discloses a steel bar resistant to marine weather corrosion. The steel bar contains 0.2-0.25% C, 0.05-0.30% Cu, 0.04-0.25% Ni, and 0.05-0.30% Cr. Compared with ordinary steel bars, Although its resistance to wet marine climate has been greatly improved, due to the high C content and low alloy content, it is easy to form localized corrosion in dry and wet harsh environments, which is not conducive to dry and wet areas such as ocean splash areas and tidal areas. The improvement of corrosion performance in corrosive environment is difficult to meet the service life requirements of existing buildings

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