A wire rod rolling method for eliminating fine grains on the surface of low carbon steel

Abstract

The invention discloses a wire rod rolling method for eliminating fine grains on the surface of low-carbon steel. The wire rod rolling method comprises the steps that 1, the heating section temperature of a steel billet is 930 DEG C-970 DEG C, the soaking section temperature is 1040 DEG C-1070 DEG C, and the soaking time is shorter than or equal to 0.5 h; 2, the start rolling temperature is 930 DEG C-960 DEG C, water tanks adopt a group of consequent air cooling nozzles, 8-12 groups of water cooling nozzles and three groups of reverse air cooling nozzles before and after precision rolling, the air nozzle pressure is 0.07-0.40 MPa, the water nozzle pressure is 0.55-0.70 MPa, the precision rolling inlet temperature is 935 DEG C-965 DEG C, and the flow quantity of the first water tank and the flow quantity of the second water tank are 1000-1600 l / min before precision rolling is conducted; and 3, after precision rolling is conducted, the flow quantity of the first water tank is 600-800 l / min, the flow quantity of the third water tank is 500-700 l / min, the flow quantity of the fifth water tank is 400-600 l / min, the second water tank and the fourth water tank are closed, and the spinning temperature is 915 DEG C-935 DEG C.

Description

technical field [0001] The invention belongs to the field of iron and steel metallurgy, and in particular relates to a wire rod rolling method for eliminating fine grains on the surface of low-carbon steel. Background technique [0002] Conventional rolling of the surface structure of low-carbon steel wire rod is easy to form a fine-grained layer, which will cause the surface structure to be hard, and the difference in the thickness of the internal and external structures will easily lead to inconsistent deformation, which is not conducive to drawing or cold heading. Work hardening will occur during drawing. The fine-grained area on the surface will generate a large stress, resulting in poor coordinated deformation ability for further drawing, and increasing the broken wire rate in the drawing process; for low-carbon steel for cold heading, the structure produced by the wire rod after drawing is not good Uniformity will also be inherited to metal products, and heat treatment...

AI Technical Summary

Problems solved by technology

[0002] Conventional rolling of the surface structure of low-carbon steel wire rod is easy to form a fine-grained layer, which will cause the surface structure to be hard, and the difference in the thickness of the internal and external structures will easily lead to inconsistent deformation, which is not conducive to drawing or cold heading. Work hardening will occur during drawing. The fine-grained area on the surface will generate a large stress, resulting in poor coordinated deformation ability for further drawing, and increasing the broken wire rate in the drawing process; for low-carbon steel for cold heading, the structure produced by the wire rod after drawing is not good Uniformity will also be inherited to metal products, and heat treatment is also difficult to eliminate

[0003] The wire drawing process often requires energy saving, environmental protection, high efficiency, etc. Some wire rods often hope not to go through annealing, and the negative impact caused by uneven organization is more serious. Some wire rods often need to be drawn to very thin specifications such as 0.75mm or less. The wire is often delayed for more than 0.5 hours, so the wire drawing process requires a low wire breakage rate. The wire breakage rate of high-quality low-carbon steel wire drawing is expected to be no more than 0.5 times / ton, while the conventional rolling process often has surface fineness. Grains, resulting in uneven structure increases the frequency of broken wires during the drawing process, so it is particularly important to eliminate the fine grains produced on the surface of the wire rod

[0004] In the process of wire rod rolling, due to the conventional heating and rolling process, the structure differences between the surface and the core are often ignored, and the wire rod often uses water tank spraying to control the temperature, the water flow of the water tank, the opening degree of the water valve, etc. 1. Water pressure adjustment often only pays attention to the cooling effect, which cannot ensure the uniformity of the structure, and it is easy to cause the surface temperature to be too low, and a fine-grained layer is formed on the surface of the wire rod, and the center is formed due to deformation and heating, which causes the non-surface structure to form a large grains, forming an uneven structure on the outside and inside, which will have an adverse effect on the drawing performance

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