Production method for eliminating annular mixed crystals of cable steel wire rod

Abstract

The invention provides a production method for eliminating annular mixed crystals of a cable steel wire rod. The production process of the cable steel wire rod comprises the steps of heating of a heating furnace, rough rolling, intermediate rolling, pre-finish rolling, water tank and recovery section treatment, finish rolling, water tank and recovery section treatment, spinning, cooling of an air cooling roller way, coil collecting, trimming, bundling, weighing, plate hanging and warehousing. The heating section is 1100 + / -40 DEG C, the soaking section is 1050 + / -40 DEG C, the rolling starting temperature is controlled to be 940 + / -10 DEG C, the finish rolling temperature is not controlled, the spinning temperature is controlled to be 930-950 DEG C, only 1 # and 18 # heat preservation covers are opened, and all the rest parts are closed. Annular mixed crystals caused by rolling in a two-phase region are eliminated, and the drawing performance of the wire rod is improved.

Description

Technical Field

[0001] The present invention relates to the field of steel rolling, and particularly relates to a production method for eliminating circular mixed crystals in cable steel wire rods. Background Art

[0002] Cable steel is widely used in fields such as communication, electronics, transportation, and rubber products, with a broad market prospect and high economic benefits. Steel for cables, also known as copper-clad steel, the main use of cable steel wire rods is to make copper-clad steel wires. Copper-clad steel wires combine the advantages of steel and copper, having advantages such as light weight, no creep, and corrosion resistance, and are substitutes for pure copper wire products. Drawing performance and conductivity are key indicators for measuring the quality of cable steel wire rods. The final finished product has a minimum diameter of 0.09 mm, so the quality requirements for raw materials are very high. This steel grade has a relatively low Mn / S ratio, and its plasticity is relatively low in the temperature range of 970 - 1050 °C, and the rolling process is prone to causing billet cracking. Currently, major domestic steel mills generally adopt a high-temperature / low-temperature rolling route for the rolling of cable steel wire rods to avoid the high-temperature hot brittleness zone. High-temperature rolling increases both gas consumption and billet loss. If the rolling start temperature is controlled within the range of 970 - Ar3 temperature, the rolling process will pass through the two-phase zone rolling, thereby causing circular mixed crystals. If not controlled well, the circular mixed crystal structure remaining in the finished product will cause wire breakage during the drawing process, affecting the user experience. If the rolling start temperature is controlled below Ar3, the temperature of the entire rolling process is relatively low, the deformation resistance of the billet is large, and it is more harmful to the equipment.

[0003] In summary, the following problems exist in the prior art: Circular mixed crystals are easily caused during the production of cable steel, and subsequent wire breakage during drawing is likely to occur. Summary of the Invention

[0004] The present invention provides a production method for eliminating circular mixed crystals in cable steel wire rods to solve the problems of easy occurrence of circular mixed crystals during the production of cable steel and subsequent wire breakage during drawing.

[0005] For this purpose, the present invention proposes that the production method for eliminating circular mixed crystals in cable steel wire rods includes:

[0006] The production process of cable steel wire rods is: heating in a heating furnace, rough rolling, medium rolling, pre-finishing rolling, water tank and recovery section, finishing rolling, water tank and recovery section, wire laying, air-cooling roller table cooling, coiling, trimming, bundling, weighing, tagging, and warehousing;

[0007] The square billet is heated in a heating furnace, with the heating section at 1100 ± 40 °C, the soaking section at 1050 ± 40 °C, the rolling start temperature controlled at 940 ± 10 °C, the temperature entering the finishing rolling is not controlled, the wire laying temperature is controlled at 930 - 950 °C, and only the 1# and 18# of the heat preservation covers are opened, and the rest are all closed.

[0008] Furthermore, control the heating temperature of the continuous casting billet at 1080 - 1120 °C, the heating time of the steel billet at 80 - 120 minutes, the starting rolling temperature at 930 - 950 °C, adopt 28 - stand high - speed non - twisting rolling, the temperature entering the finishing mill is not controlled, the measured temperature of the finishing mill is 890 - 900 °C, the coiling temperature is controlled at 930 - 950 °C, the heat preservation covers of No. 1 and No. 18 are open, and the rest are closed.

[0009] The chemical composition of the said wire rod for cable steel is by weight percentage:

[0010] C ≤ 0.004, Si ≤ 0.01, Mn: 0.035 - 0.06, P ≤ 0.01, S ≤ 0.008, and the rest is Fe element.

[0011] The beneficial effects of the present invention are as follows: The present invention adopts a low - temperature starting rolling route, avoiding the high - temperature hot - brittle zone (970 - 1050 °C) of the cable steel. By using the controlled rolling technology and reasonable rolling temperature control, the circular mixed crystal caused by rolling in the two - phase zone is eliminated, the drawing performance of the wire rod is improved, and at the same time, the gas consumption and billet loss caused by high - temperature rolling are reduced. Brief Description of the Drawings

[0012] Figure 1 It is the metallographic structure photo of the cross - section of the wire rod in Example 1 of the present invention;

[0013] Figure 2 It is the metallographic structure photo of the cross - section of the wire rod in Example 2 of the present invention;

[0014] Figure 3 It is the metallographic structure photo of the cross - section of the wire rod in Example 3 of the present invention;

[0015] Figure 4 It is the metallographic structure photo of the cross - section of the wire rod in Comparative Example 1 of the present invention;

[0016] Figure 5 It is the metallographic structure photo of the cross - section of the wire rod in Comparative Example 2 of the present invention;

[0017] Figure 6 It is the metallographic structure photo of the cross - section of the wire rod in Comparative Example 3 of the present invention. Detailed Embodiments

[0018] In order to have a clearer understanding of the technical features, objectives and effects of the present invention, the present invention is now described.

[0019] The principle of the present invention is as follows: The high-temperature hot brittleness zone of cable steel is 970 - 1050 °C. The starting rolling temperature is set at 940 ± 10 °C to avoid billet cracking caused by rolling in the hot brittleness zone. The Ar3 temperature of this steel grade is around 910 °C. During the rolling process, deformation-induced phase transformation will increase the Ar3 temperature. Therefore, the rolling process will inevitably pass through the two-phase zone rolling, resulting in the occurrence of annular mixed crystals. If not controlled properly, the annular mixed crystal structure remaining in the finished product will cause wire breakage during the wire drawing process, affecting the user experience. Therefore, during the finishing rolling stage, no controlled cooling is carried out, and the temperature rise during the finishing rolling stage is fully utilized to eliminate the annular mixed crystal structure. At the same time, the laying head temperature is controlled at 930 - 950 °C to ensure appropriate grain size and tissue uniformity of the wire rod. At the same time, in order to ensure the conductivity of the wire rod, the grains cannot be too fine. The insulation covers 1# and 18# are opened, and the rest are closed to ensure the uniform growth of ferrite after phase transformation.

[0020] The specific technical measures include:

[0021] 1. The production process of cable steel wire rod is: heating furnace heating → rough rolling → intermediate rolling → pre-finishing rolling → water tank and recovery section → finishing rolling → water tank and recovery section → laying head → air-cooling roller table cooling → coiling → trimming, bundling, weighing, tagging, warehousing.

[0022] The square billet is heated in the heating furnace. The heating section is at 1100 ± 40 °C, the soaking section is at 1050 °C, the starting rolling temperature is controlled at 940 ± 10 °C, the temperature entering the finishing rolling is not controlled, the laying head temperature is controlled at 930 - 950 °C, and only the insulation covers 1# and 18# are opened, and the rest are all closed. Specific embodiments

[0024] (1) The production process of cable steel wire rod is: heating furnace heating → rough rolling → intermediate rolling → pre-finishing rolling → water tank and recovery section →

[0025] finishing rolling → water tank and recovery section → laying head → air-cooling roller table cooling → coiling → trimming, bundling, weighing, tagging, warehousing. The chemical composition of the cable steel wire rod of the present invention is shown in Table 1 by weight percentage

[0026] Table 1 Chemical composition of the cable steel wire rod of the present invention by weight percentage (the rest is Fe element)

[0027] element C Si Mn P S composition ≤0.004 ≤0.01 0.035-0.06 ≤0.01 ≤0.008

[0028] (2) The composition of Example (Example) 1 is C: 0.0019, Si: 0.0037, Mn: 0.038, P: 0.0054, S: 0.0058, and the rest is Fe element

[0029] (Example) 2 and 3 are from the same furnace, and their composition is C: 0.0012, Si: 0.0012, Mn: 0.039, P:

[0030] 0.0044, S: 0.005, the rest is Fe element

[0031] The size of the incoming billet is: 165mm * 165mm * 9300mm, and the finished size of the wire rod is 6.5mm. Control the heating temperature of the continuous casting billet at 1080 - 1120 °C, the heating time in the heating section of the billet is 80 - 120 minutes, the rolling start temperature is 930 - 950 °C, adopt 28 - stand high - speed non - twist rolling, the temperature entering the finishing mill is not controlled (the measured temperature is 890 - 900 °C), the laying - head temperature is controlled at 930 - 950 °C, the heat - preservation covers 1# and 18# are open, and the rest are closed.

[0032] In Comparative Examples 1 - 3, control the heating temperature of the continuous casting billet at 1080 - 1120 °C, the heating time of the billet is 80 - 120 minutes, the rolling start temperature is 930 - 950 °C, adopt 28 - stand high - speed non - twist rolling, the temperature entering the finishing mill is controlled at 840 - 850 °C, the laying - head temperature is controlled at 840 - 860 °C, the heat - preservation covers 1# and 18# are open, and the rest are closed.

[0033] The comparison of the rolling temperature parameters between the examples (embodiments) of the present invention and the comparative examples is shown in Table 2

[0034] Table 2 Rolling temperature parameters of the examples (embodiments) of the present invention and the comparative examples

[0035] example inlet material number total heating time preheating section heating section temperature soaking section temperature rolling start temperature entry into finishing mill temperature spinning temperature Example 1 24B203226101 118 542 1092 1043 947 894 946 Example 2 24B20322701 120 543 1096 1044 947 891 935 Example 3 24B203227102 116 544 1118 1045 948 894 950 Comparative Example 1 24B203227103 116 545 1109 1052 945 844 845 Comparative Example 2 24B203227201 118 547 1080 1045 948 845 848 Comparative Example 3 24B203229101 117 549 1083 1049 938 849 845

[0036] Figure 1 、 Figure 2 and Figure 3 are the metallographic structure photos of the cross - section of the wire rod in the examples of the present invention, Figure 4 、 Figure 5 and Figure 6 are the photos of the annular mixed crystals in the comparative examples (the outer layer structure is coarse, the inner layer structure is fine, with an obvious ring), Figure 1 - Figure 6 is the metallographic structure photo obtained by observing the cross - section of the wire rod after grinding, polishing, and etching with 4% nitric acid alcohol for 10 seconds under a metallographic microscope. All the pictures are magnified 12.5 times.

[0037] According to the metallographic structure photos of Examples 1 - 3, namely Figure 1 、 Figure 2 、 Figure 3 and the metallographic structure photos of the comparative examples, namely: Figure 4 、 Figure 5 and Figure 6 , it can be seen that the metallographic structures of Examples 1 - 3 have no annular mixed crystal structure, and the comparative examples Figure 4 、 Figure 5 and Figure 6Photo of the ring mixed crystal. The outer structure is coarse, the inner structure is fine, and there is an obvious ring shape. Therefore, according to the rolling method of the present invention, the ring mixed crystal structure can be eliminated. For the wire rods with ring mixed crystal structure in Comparative Examples 1-3, when the wire rods with ring mixed crystal are drawn to 1.5 mm (before heat treatment), the wire breakage rate is 3-4 times per ton of material. After heat treatment and copper plating, when drawn from 1.5 mm to 0.7-0.8 mm, the wire breakage is 15-16 times per ton of material, and it is impossible to further draw to the double zero wire (0.08 mm - 0.10 mm). For the wire rods in Examples 1-3 of the present invention, there is no wire breakage before medium drawing. After heat treatment and copper plating, when drawn from 1.5 mm to 0.7-0.8 mm, the wire breakage is 0.5 times per ton of material, and the wire breakage rate when drawn to the double zero wire is 0.8 times per ton of material.

[0038] The main mechanical properties, drawing properties and conductivity of the present invention are shown in Table 3

[0039] Table 3: Table of the main mechanical properties, drawing properties and conductivity of each example

[0040]

[0041] The above is only a schematic specific embodiment of the present invention and is not intended to limit the scope of the present invention. The components of the present invention can be combined with each other under the condition of not conflicting. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A production method for eliminating annular mixed crystals in cable steel wire rods, characterized in that: The production method for eliminating the annular mixed crystals of cable steel wire rods comprises: The production process of cable steel wire rod is as follows: heating in heating furnace, rough rolling, intermediate rolling, pre-finishing rolling, water tank and recovery section, finishing rolling, water tank and recovery section, wire laying, air-cooled roller cooling, coiling, trimming, bundling, weighing, labeling, and storage; The square billet is heated in a heating furnace, the heating section is at 1100±40℃, the soaking section is at 1050℃±40℃, the starting rolling temperature is controlled at 940±10℃, the finishing rolling temperature is not controlled, the wire laying temperature is controlled at 930-950℃, and only 1# and 18# insulation covers are opened, and the rest are all closed.

2. The production method for eliminating annular mixed crystals in cable steel wire rods according to claim 1, characterized in that: The heating temperature of the ingot heating section is controlled at 1080-1120°C, the billet heating time is 80-120 minutes, the starting rolling temperature is 930-950°C, 28-frame high-speed torsion-free rolling is adopted, the finishing rolling temperature is not controlled, the actual finishing rolling temperature is 890-900°C, the wire drawing temperature is controlled at 930-950°C, insulation covers 1# and 18# are opened, and the rest are closed.

3. The production method for eliminating annular mixed crystals in cable steel wire rods according to claim 1, characterized in that: The heating temperature of the ingot is controlled at 1080-1120°C, the heating time of the ingot is 80-120 minutes, the rolling temperature is 930-950°C, 28-frame high-speed torsion-free rolling is adopted, the finishing rolling temperature is controlled at 840-850°C, the wire drawing temperature is controlled at 840-860°C, the insulation covers 1# and 18# are opened, and the rest are closed.

4. The production method for eliminating annular mixed crystals in cable steel wire rods according to claim 1, characterized in that: The chemical composition of the cable steel wire rod is as follows by weight percentage: C≤0.004%, Si≤0.01%, Mn: 0.035-0.06%, P≤0.01%, S≤0.008%, and the rest is Fe element.

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