Cold heading steel hot rolled wire rod for large-size wind power bolts and preparation method thereof

Abstract

The invention belongs to the field of cold heading steel hot rolled wire rods and relates to a cold heading steel hot rolled wire rod for large-size wind power bolts and a preparation method thereof.The cold heading steel hot rolled wire rod comprises, by weight, 0.38-0.43% of C, 0.21-0.35% of Si, 0.80-1.00% of Mn, less than or equal to 0.020% of P, less than or equal to 0.010% of S, 0.80-1.10% of Cr, 0.15-0.25% of Mo, 0.020-0.050% of Al, and the balance Fe and inevitable impurity elements. The preparation method comprises the large square bloom heating step: heating a steel billet to 1230-1260 DEG C, conducting heat preservation for 340-380 min, and maintaining the remaining oxygen amount of a heating furnace 0.5%-2.5%; the hot rolled billet heating step: heating the steel billet to 1100-1140 DEG C, conducting heat preservation for 90-120 min, and maintaining the remaining oxygen amount of the heating furnace 1.0%-4.0%; the controlled rolling step: maintaining the finish rolling temperature 910-940 DEG C and the laying temperature 750-790 DEG C; and the controlled cooling process: blowing air to cool the wire rods after laying, cooling the wire rods to 550-570 DEG C at the rate of 1.0-2.0 DEG C/s, and feeding the wire rods into an operating channel covered with a heat preservation cover to be subjected to slow cooling for 25-40 min. The wire rods are used for manufacturing 10.9-grade high-strength wind power bolts and have the good low-temperature impact toughness.

Description

technical field [0001] The invention belongs to the field of cold heading steel hot-rolled wire rods, and relates to a cold heading steel hot-rolled wire rod for large-scale wind power bolts and a preparation method thereof. Background technique [0002] As the most basic components in various industries, fasteners are not only subjected to axial pretension tensile loads, but also to additional tensile alternating loads, transverse shear alternating loads, or the combination of these The resulting bending load. In addition to the above-mentioned stress conditions, the wind power bolts also withstand the erosion and test of severe heat and cold, extreme temperature difference, and salt spray corrosion all year round together with the main engine. Therefore, in addition to ensuring sufficient strength and plasticity of wind power bolts, sufficient low temperature impact toughness is also required. [0003] At present, most of the domestic high-strength wind power bolts choos...

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Problems solved by technology

[0010] Existing inventions, or through low-temperature rolling + low-temperature spinning control to achieve fine grain control, but some rolling equipment has the problem of low-temperature rolling load overload; or by adding precious alloys Ni and Nb, through fine-grain control and increasing material stacking faults can reduce the sensitivity of low-temperature notch, etc., but the products studied are either rods or the heat treatment properties do not meet the performance of 10.9 wind power bolts; or the low-temperature impact properties of steel are improved by changing the heat treatment process, but the fasteners are double-ended The Rockwell hardness of the stud after heat treatment is: HRC26-30, the product hardness does not meet the requirements of 10.9 wind power bolts, and the cooling method is room temperature cooling after tempering, which is not conducive to avoiding high temperature tempering brittleness

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