A method of manufacturing heat-treated prestressed steel strands

Abstract

The invention discloses a production method for a thermal treatment prestressed steel strand. According to the production method for the thermal treatment prestressed steel strand, AISI4340MOD steel is selected as raw materials and theAISI4340MOD steel comprises the following componentsby mass percent, 0.3 to 0.32 % of carbon, 0.18 to 0.36 % of silicon, 0.50 to 0.70 % of manganese, 0.90 to 1.10 % of chromium, 0.20 to 0.30 % of molybdenum, 0 to 0.02 % of phosphorus, 0 to 0.025 % of sulfur, 0 to 1.8 ppm of hydrogen, 0 to 0.40 % of nickel, 0 to 0.03 % of vanadium, 0 to 0.30 % of copper, 0 to 0.9 % of residual elements and the remaining is ferrum. The production method for the thermal treatment prestressed steel strand has the advantages of improving the strength and hardenability of the steel strand, enabling the steel strand to be not easy to craze, low in looseness, uniform and smooth in surficial galvanization.

Description

technical field [0001] The invention relates to a method for manufacturing heat-treated prestressed steel strands. Background technique [0002] In the prior art, the atomic activity of carbon and nitrogen elements in the raw material composition is low, and the air mass formed by each atom cannot form a strong interaction with the dislocation, and the dislocation can be activated without providing a large external stress, so that the performance It is very unstable, and at the same time, the hydrogen content in the steel bar forging blank is above 2.0ppm, and the steel bar forging blank is prone to cracks, thereby inducing hydrogen-induced cracks and hydrogen-induced delayed hysteresis cracks. [0003] In the prior art, only a single quenching method is generally used, so that the quenching cracking and internal cracking of the forging cannot be prevented. At the same time, the carbides cannot be further fully dissolved and cannot be uniformly diffused, so that the precipit...

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Problems solved by technology

[0002] In the prior art, the atomic activity of carbon and nitrogen elements in the raw material composition is low, and the air mass formed by each atom cannot form a strong interaction with the dislocation, and the dislocation can be activated without providing a large external stress, so that the performance Very unstable, and at the same time, the hydrogen content in the forging steel bar is above 2.0ppm, and the forging steel bar is prone to cracks, which induces hydrogen-induced cracks and hydrogen-induced delayed hysteresis cracks

[0003]In the prior art, only a single quenching method is generally used, so that the quenching cracking and internal cracking of the forging cannot be prevented, and the carbides cannot be further fully dissolved, and the uniformity cannot be achieved. Diffusion, so that the precipitation of carbides between grains cannot be avoided, resulting in excessive intergranular corrosion and pitting corrosion, which affects the technical effect of the heat treatment process after smelting.

[0004] At the same time, in our conventional steel strand galvanizing process, improper selection of galvanizing solution, concentration, PH value and electroplating current will cause poor electroplating effect , and the activity in the electroplating solution is poor, which will not only cause uneven galvanizing, but also surface galvanizing defects, and the electroplating is not uniform and smooth.