A steel bar for high-ductility ultra-high-strength prestressed concrete and its processing method

Abstract

The present invention relates to a steel rod for high ductility and ultra-high strength prestressed concrete and a processing method thereof. The weight percent of its chemical composition is: C: 0.3-0.5%, Si: 0.3-1.8%, Mn: 0.6-1.5%, Nb : 0.02-0.2%, V: 0.01-0.1%, Ni: 0.01-0.2%, Cr: 0.1-0.5%, Mo: 0.01-0.1%, B: 0.001-0.005%, Fe: balance, of which carbon equivalent Ceq Less than 0.8%. The online continuous ultra-high pressure quenching control technology can make the strength of the product greater than 1860MPa, even more than 2000MPa. The online continuous tempering heat preservation and temperature control technology adopted in the present invention can make the elongation of the steel bar more than 7%, and maintain a small amount of ultra-fine ferrite + tempered troostite structure state, and has good ductility and hysteresis resistance Fractured properties.

Description

technical field [0001] The invention relates to a steel rod for concrete and a processing method thereof, in particular to a steel rod for high ductility ultra-high strength prestressed concrete and a processing method thereof. Background technique [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 d...

AI Technical Summary

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