High-strength bolt steel with excellent resistance to atmospheric corrosion and delayed fracture

Abstract

The invention discloses a high-strength bolt steel with excellent resistance to atmospheric corrosion and delayed fracture. The high-strength bolt steel with excellent resistance to atmospheric corrosion and delayed fracture comprises, by mass, 0.30-0.45% of C, below 0.25% of Si, 0.40-1.40% of Mn, below 0.012% of P, below 0.008% of S, 0.40-1.20% of Cr, 0.15-0.50% of Mo, 0.30-1.20% of Ni, 0.20-0.60% of Cu, 0.05-0.20% of V, 0.005-0.030% of Re, and the balance of Fe and inevitable impurity elements. Compared with steels in the prior art, the high-strength bolt steel with excellent resistance to atmospheric corrosion and delayed fracture has the advantages of high strength, excellent resistance to atmospheric corrosion and delayed fracture, and low cost, and can be used to 12.9 level high-strength bolts for bridges and other steel structures.

Description

technical field [0001] The invention relates to the field of alloy steel. More specifically, it relates to a high-strength bolt steel with excellent atmospheric corrosion resistance and delayed fracture resistance. Background technique [0002] Steel structure is widely used in infrastructure construction because of its high strength, light weight, short construction period, low foundation cost and good earthquake resistance. However, the use of steel structures in various atmospheric environments will cause corrosion. For this reason, domestic steel structures are basically anti-corrosion by coating. However, the anti-corrosion period of surface spraying and other methods is generally 5 to 10 years. Due to the aging and differentiation of the coating, regular maintenance and re-corrosion coating must be carried out. The coating process will cause environmental pollution and increase costs. Therefore, foreign countries, especially the United States, started the application...

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Problems solved by technology

Chinese application patents 2017101375650.8 and 201710375670.5 respectively propose industrial atmospheric corrosion-resistant high-strength bolt steel for paint-free steel structures and its manufacturing method, and industrial atmospheric corrosion-resistant high-strength bolt steel for paint-free bridge structures and its manufacturing method. The tensile strength level of steel is 1000-1200MPa, which can only be used to manufacture high-strength bolts of grade 10.9, which is difficult to meet the requirements of high-strength bolts of grade 12.9 for long-span paint-free bridges; in addition, the content of impurity elements P in steel is relatively high , although it has a good effect of improving weather resistance, it seriously deteriorates the delayed fracture resistance of steel

In addition, the 1300MPa-class delayed-fracture-resistant high-strength bolt steel ADS3 (鉄と钢, 1996, 82:297) developed by Japan’s Sumitomo Metal and a delayed-fracture-resistant bolt with a tensile strength of 1300-1500MPa invented by Chinese patent CN00105872.X Steel, although it can be used to manufacture high-strength bolts with a strength level of 12.9 and above, does not consider weather resistance, and it is also difficult to meet the atmospheric corrosion resistance requirements of high-strength bolts for steel structures such as bridges

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