600MPa level quake-proof twisted steel and manufacturing method thereof

Abstract

The invention discloses 600MPa level quake-proof twisted steel and a manufacturing method of the steel. The twisted steel comprises one or the combination of more than two of the following components in percentage by weight: 0.21-0.26% of C, 0.61-0.80% of Si, 1.30-1.60% of Mn, 0.15-0.21% of V, 0.001-0.050% of Nb, 0.001-0.050% of Ti, 0.10-0.50% of Cr, 0.0001-0.0050% of B, 0.001-0.010% of Mo and the balance of Fe and unavoidable impurities, wherein the components of C, Si, Mn and V are basic components, and the components of Nb, Ti, Cr, B and Mo are optional components. A short-flow process of converter or electric furnace smelting and small billet continuous casting and rolling and cold bed cooling is adopted by the manufacturing method of the twisted steel. The tensile strength of the twisted steel produced by adopting the components and the method is more than 730MPa, the yield strength is more than 600MPa, the percentage elongation after fracture is more than 14%, the maximum force percentage of total elongation is more than 9%, and the yield ratio is more than 1.25, so the international requirement of quake resistance on the twisted steel can be met.

Description

technical field [0001] The invention relates to a 600MPa-grade anti-seismic threaded steel bar and a manufacturing method thereof, belonging to the fields of iron and steel metallurgy and steel rolling. Background technique [0002] Threaded steel bars are widely used in basic buildings such as dams, factory buildings, roads and bridges. Under the same conditions of use, increasing the yield strength of threaded steel bars can reduce the diameter of steel bars, save steel consumption, reduce engineering costs, and also reduce the weight of steel structures , shorten the project cycle. As of 2011, the use of steel bars with a strength level of 400MPa and above in my country only accounted for 40% of the total. Most foreign countries use steel bars of 400MPa and above. In recent years, the state has introduced a series of measures to vigorously promote high-strength threaded steel bars. For example, the newly launched "Code for Design of Concrete Structures" on July 1, 2011 ...

AI Technical Summary

Problems solved by technology

[0004] 1. Finish rolling adopts low-temperature and large-reduction rolling, which has high requirements on the performance of the rolling mill. It is not suitable for the production of old-fashioned rolling mills, and it is difficult to apply in large quantities at the current stage;

[0005] 2. Nitrogen blowing throughout the whole process and too high N content will easily cause too many subcutaneous bubbles in the billet, which will affect the quality of the finished product