Method for controlling structural homogeneity of high-carbon steel coil rod for deep drawing of steel wire

Abstract

The invention discloses a method for controlling the structural homogeneity of a high-carbon steel coil rod for deep drawing of a steel wire and belongs to the technical field of steel rolling. The method comprises the following steps of: for precision rolling, controlling precision-rolling inlet temperature and precision-rolling temperature rising by using a ten-rack continuous rolling technology, wherein the precision-rolling inlet temperature is controlled to be 880 to 920 DEG C, and the precision-rolling temperature rising is controlled to be 90 to 110 DEG C; after rolling, quickly cooling and fully recovering to guarantee a proper spinning temperature; after precision rolling, performing cooling by using five water cooling boxes, reducing the temperatures of the first, second and third water cooling boxes to be 40 to 50 DEG C, reducing the temperatures of the fourth and fifth water cooling boxes to be 0 to 10 DEG C, and controlling spinning temperature to be 880 to 920 DEG C; andafter spinning, controlling the cooling speed rate of the coil rod before phase change on a Stelmor air-cooling line and the range of a phase change temperature interval, wherein the control range ofthe cooling speed rate of the coil rod before phase change is 15 to 20 DEG C / s, and the phase change temperature interval is 580 to 620 DEG C. The method has the advantages that: the sorbite grain size of an edge part and a core part of the produced coil rod is controlled to be in a range of 7 to 9 grades; the proportion of an isometric sorbite group is greater than 70 percent; and the structuralhomogeneity is better.

Description

technical field [0001] The invention belongs to the technical field of steel rolling, and in particular provides a method for controlling the microstructure uniformity of high-carbon steel wire rods for deep drawing steel wires. It is used in high-speed wire rod factories in the iron and steel metallurgical industry to produce high-carbon steel hot-rolled wire rods that meet the needs of users for deep drawing. Background technique [0002] A control method for the microstructure uniformity of high-carbon steel wire rods for deep-drawing steel wires, applied in the field of steel rolling, suitable for the production of high-grade deep-drawn wire rods in steel rolling workshops, and meeting the requirements of deep-processing enterprises for the uniformity of microstructure and properties of hot-rolled wire rods Require. [0003] The uniformity of wire rod structure and performance directly affects the performance of deep processing, mainly in the drawing broken wire rate, s...

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Problems solved by technology

Moreover, the cooling rate of 2-10°C after rolling introduced in this patent is difficult to ensure the best sorbite ratio of cord steel wire rod, and even cannot suppress the precipitation of proeutectoid cementite, and the process parameters are debatable

[0005] Patent CN1184718A states a process for deep-processing cord steel, but it only limits the water volume of the water-cooled box and the air volume of the air-cooled fan, and the practical operability of the process is not strong: first, only the water volume is limited, and the It cannot guarantee the rapid cooling of the wire rod after rolling and the need to suppress the abnormal growth of deformed austenite in the finish rolling; second, the cooling capacity of the wind has a great influence on the humidity of the day and the ambient temperature, and the temperature difference between winter and summer in the north is more than 40 ℃. Process guarantee conditions are difficult to control the stability of wire rod structure and performance

[0006] At present, most high-end wire rods adopt finishing rolling mills and finishing rolling + reducing and sizing equipment. The advantage of finishing rolling process lies in the accumulation of deformation and obvious microstructure, which is very suitable for the development of high carbon steel wire rods. However, finishing rolling In the continuous rolling production, the control of the finish rolling temperature rise is often neglected. At present, the finish rolling speed of the wire rod is above 100m / s, and the true strain rate is above 1000s-1, so the temperature rise of the finish rolling of the wire rod is generally above 130°C, resulting in The temperature of the wire rod exiting the finishing mill reaches about 1050°C, which can easily cause abnormal growth of the austenite structure and seriously affect the uniformity of the wire rod structure; while the reduction and sizing technology distributes the deformation into two different processes, most It is 8 stands of finishing rolling + 4 stands of reducing and sizing, which reduces the deformation temperature rise in the finishing rolling process, and at the same time uses the deformation of reducing and sizing to ensure the reduction rate of the wire rod, but the equipment is relatively complicated, the equipment investment is large, and the production cost is also high.

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