Ultra-large-specification low-relaxation prestress steel strand and manufacturing method thereof

Abstract

The invention belongs to the technical field of prestress steel strands, in particular to a 1*7 structure ultra-large-specification low-relaxation prestress steel strand and a manufacturing method thereof. The steel strand comprises a center wire and six outer-layer edge wires, the diameter of the center wire ranges from 8.16 mm to 8.26 mm, the diameter of each outer-layer edge wire is 7.78-7.88 mm, the increase ratio of the center wire is 4-6%, the width of the gap between every two adjacent edge wires is 0.2-0.3 mm, and the nominal diameter of entwisted outer-layer edge wire and center wireis 23.6 mm. The manufacturing method of the ultra-large-specification low-relaxation prestress steel strand includes the steps of drawing, twisting and stabilizing treatment under tension tempering. The tension value of the center wire obtained after drawing is larger than or equal to 96. 82 kilonewtons, and the tensile value of the outer-layer edge wires obtained after drawing is larger than or equal to 88.60 kilonewtons. The tensile strength of the ultra-large-specification low-relaxation prestress steel strand obtained after twisting and stabilization treatment is larger than or equal to 1770 MPa, the maximum force is larger than or equal to 602.00 kilonewtons, the total elongation of the maximum force reaches 4.5% or above, and the relaxation value within 1000 hours is smaller than 2.5%.

Description

technical field [0001] The invention belongs to the technical field of prestressed steel strands, and relates to a steel strand with a 1×7 structure, in particular to an ultra-large-sized low-relaxation prestressed steel strand and a manufacturing method thereof. Background technique [0002] Prestressed construction technology has been rapidly developed in application fields such as highways, intercity express railways, super high-rise buildings, water conservancy and hydropower engineering, nuclear power plant engineering, and coal mining. In some fields, prestressed geotechnical anchoring technology is required for slope reinforcement. , geological disaster protection, deep foundation pit excavation, iron (highway) road tunnel and support of coal mining roadway. [0003] Prestressed steel strands are mainly used in railway highway bridges, long-span cable-stayed bridges, mine roadway support, and geotechnical anchoring works. The requirements for the size and bearing cap...

AI Technical Summary

Problems solved by technology

Moreover, the process parameters in each step need to be tested repeatedly to obtain the most optimal solution, but there are various problems in the existing process, such as: the raw material rolling level is not high, resulting in large-scale (ordinary YL82BΦ14.0 mm) discs The state of the strip structure is not ideal, the original tensile strength does not meet the requirements, the drawing strengthening coefficient is not high, resulting in low tensile strength of the steel wire, rough design of raw material drawing process parameters, or improper selection of stabilization parameters after twisting. As a result, the finished products of super-large steel strands have defects such as loose structure, reduced tensile strength, unsatisfactory relaxation performance or low relaxation performance.

Images