Steel bar for high-ductility and superhigh-strength pre-stressed concrete and machining method thereof

Abstract

The invention discloses a steel bar for high-ductility and superhigh-strength pre-stressed concrete and a machining method of the steel bar. The steel bar comprises, by weight, 0.3-0.5% of C, 0.3-1.8% of Si, 0.6-1.5% of Mn, 0.02-0.2% of Nb, 0.01-0.1% of V, 0.01-0.2% of Ni, 0.1-0.5% of Cr, 0.01-0.1% of Mo, 0.001-0.005% of B and the balance Fe, wherein the Ceq is smaller than 0.8%. Because an online continuous superhigh-pressure quenching control technology is adopted, the strength of the steel bar can be larger than 1860MPa or even larger than 2000MPa; because an online continuous quenching heat insulation and control technology is adopted, the ductility of the steel bar can be larger than 7%, the structural state of few ultra fine ferrites and tempered troostite is kept, and the steel bar has the advantages of being good in ductility and resistant to delayed fractures.

Description

Technical field [0001] The present invention involves a steel rod and its processing method for concrete. Specifically, it is a high -extension and high -intensity prestressed concrete steel rod and its processing method. Background technique [0002] At present, most of the prestressed concrete pipe piles produced at home and abroad use 1420MPA -level prestressed concrete steel rods (referred to as PC steel rods). Most of the raw materials used are 30mnsi, 35MNSI, etc.Put the line -peeling rust removal -stereotype -school straight -induction heating -quenching — cooling — transmission — shear division line — cluster line, although the PC steel rod has strong toughness, low, low, good welded can be welded can be weldedThe advantages of sexuality and 优 性, but the existing strength level is low, and it cannot meet the use of prestressed concrete tube piles, especially the application of prestressed concrete piles with a diameter of more than 50 meters in diameter.As we all know, th...

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Problems solved by technology

[0002] At present, most of the prestressed concrete pipe piles produced at home and abroad use 1420MPa grade prestressed concrete steel rods (referred to as PC steel rods), and most of the raw materials used are 30MnSi, 35MnSi, etc. The production and processing technology of prestressed concrete steel rods is Pay-off—peeling and derusting—shaping and notching—straightening—induction heating—quenching—tempering—cooling—transmission—shearing and splitting—rewinding, although PC steel rods have strong toughness, low relaxation, and good weldability However, the existing strength level is low, which cannot meet the application of prestressed concrete pipe piles, especially the application of prestressed concrete pipe piles with a diameter of Φ1000mm and a length of more than 50 meters.

As we all know, the tensile force of the steel in the prestressed system is maintained by 70-80% of the tensile force of the prestressed steel, and the high-strength concrete is compressed by its tension to increase the ultimate bearing capacity of the component and control the development of cracks. Therefore, 1420 grade prestressed Steel rods for stressed concrete are used in large-diameter and super-length pipe piles, and their diameter and reinforcement density are greatly increased. As a result, the steel consumption of a pipe pile of this type is about 1.3 tons, and the construction cost, transportation cost, and labor cost are greatly increased. increase, unable to meet the needs of the existing economical social development

At the same time, when the strength of the PC steel rod exceeds 1570MPa level, its elongation is less than 7%, and the sensitivity of hysteresis fracture presents a linearly increased risk. Due to the uncertainty of the occurrence time of hysteresis fracture, it may be several days , months or even years, this will cause immeasurable quality hidden dangers and huge economic losses to the steel bar industry for prestressed concrete