CN103469061A - Ultra-low carbon steel wire rod for electric conduction and production method thereof - Google Patents

Abstract

The invention provides an ultra-low carbon steel wire rod for electric conduction and its production method. 0.010%, total oxygen 0.0050～0.0080%, total aluminum ≤0.0050%. Converter smelting steel carbon content ≤ 0.040%, molten steel oxygen content 0.060%-0.070%; RH refining stage 1 natural decarburization 5-8min; second stage carbon content reduced to below 0.0030%, oxygen blowing 15-20min Carbon-free ladle smelting; continuous casting tundish molten steel superheat ≤ 30 ℃, electromagnetic stirring current ≥ 400A, casting speed 0.5-0.7m/min; entering double module temperature 880-900 ℃, spinning temperature 900-920 ℃, roll The road speed is 0.2-0.4m/s, and the fans are all turned off. The electrical conductivity of the wire rod of the invention is ≥15%, the tensile strength is ≤300MPa, and the surface shrinkage index is ≥80%, which can partially replace copper conductive materials and reduce production costs.

Description

A kind of ultra-low carbon steel wire rod for electric conduction and its production method

technical field

The invention belongs to the technical field of metallurgy, and in particular relates to an ultra-low carbon steel wire rod for electric conduction and a production method thereof.

Background technique

With the rapid development of the national economy, the requirements and consumption of conductive materials continue to increase. The traditional copper conductive material has good conductivity, but its high cost limits its wide application. The electrical conductivity of the steel material increases with the reduction of the impurity content in the steel, and the low carbon and low silicon content of the ultra-low carbon steel lays the foundation for improving the electrical conductivity of the steel. The conductive steel wire made of ultra-low carbon steel conductive wire can partially replace the copper conductive material, reduce production costs, and has a huge market application prospect.

Patent application number 200910117766.7 discloses a production method of copper-clad steel bimetallic wire rod, straightening the steel core, derusting, decontaminating and mechanical polishing; heating and melting electrolytic copper, heating the steel core, and performing horizontal continuous casting coating Copper layer; heat the copper-clad steel for rapid solution treatment; draw the copper-clad steel wire for several times in a row to make the product diameter reach 4mm--26mm; anneal the drawn copper-clad steel wire, and stretch the mold to the required Specifications are required for finished products.

Patent Publication No. CN02203241.X provides a metal-clad composite wire, which is composed of a core material, a vacuum sputtering layer coated on the periphery of the core material, and an electroplating thickening layer coated on the periphery of the vacuum sputtering layer. The outer order is set by layer wrapping. the

Patent application number 200610048186.3 discloses a copper alloy contact wire with excellent comprehensive performance and its preparation method, which belongs to the field of cable technology and is used to improve the performance of the contact wire. The technical scheme is: it uses copper alloy as raw material, and the copper alloy is smelted from raw materials with 0.05-0.35% magnesium and 0.35-0.05% tin.

Patent application number 200820047909.2 is a new type of composite metal material, which is suitable for conductive connectors in the electrical (device) industry. A layer is electroplated on both sides of the composite metal material where the copper sheet layer and the low-carbon steel sheet are laminated together. Metal nickel plating.

Patent Publication No. CN97100471.4 provides a rapid acidic bright copper plating process for low-carbon steel wire, which belongs to the method invention in the field of electrochemical technology. The invention provides an electroplating process and formula. The formula of the copper electroplating solution is mainly composed of copper sulfate, sulfuric acid, sodium lauryl sulfate and phenolsulfonic acid.

The above-mentioned patents 1-4 are all metal conductive materials related to copper or copper alloys, and patent 5 is a low-carbon steel wire bright copper plating process, which belongs to the field of electrochemical technology. The existing low-carbon steel wire rod C≤0.010%, the electrical conductivity can only reach 6-8%, and the ultra-low carbon steel wire rod C≤0.005%, the electrical conductivity can only reach 10-12%, which cannot meet the partial replacement conductivity Requirements for copper conductive materials with a rate ≥ 15%.

The novel conductive ultra-low carbon steel wire rod of the present invention adopts component design and adopts the control of the carbon and oxygen content of the steel in the converter. After the furnace, the RH vacuum refining decarburization and desiliconization improves the oxygen activity of the molten steel in the refining process. High oxygen activity reduces the aluminum content of molten steel, reduces its grain refinement effect, increases the grain size, and improves the electrical conductivity of the wire rod.

Contents of the invention

The invention aims to provide an ultra-low carbon steel wire rod for electric conduction with high electric conductivity, which can partially replace the copper electric conduction material, thereby reducing the production cost and its production method.

For this reason, the solution that the present invention takes is:

A kind of ultra-low carbon steel wire rod for electric conduction, its chemical composition wt% content is: C 0.002%～0.005%, Si 0.004%～0.010%, Mn 0.05%～0.15%, P≤0.015%, S≤0.010%, Total oxygen: 0.0050% ~ 0.0080%, total aluminum ≤ 0.0050%, the rest is iron and impurities not higher than 0.1%.

A kind of production method of ultra-low carbon steel wire rod for electric conduction, its concrete method is:

1. Control the oxygen content and low carbon content of the molten steel before RH refining, control the carbon content of the converter smelting steel to ≤0.040%, and control the oxygen content of the molten steel to 0.060%-0.070%;

2. RH refining is divided into two stages: the first stage adopts natural decarburization method, prohibits heating up and forced decarburization, and the time is 5-8 minutes; the second stage supplements the oxygen content in molten steel, blows oxygen with oxygen lance, and controls the oxygen content At 0.030%-0.050%, increase the reaction rate of carbon and oxygen to reduce the carbon content below 0.0030%, blow oxygen for 15-20 minutes, and adjust the temperature to the casting temperature, and use low-carbon or carbon-free ladle for smelting;

3. Continuous casting: Bloom protection casting is adopted, the cross-sectional size of the billet is 280×380mm, the superheat of molten steel in the tundish is ≤30°C, the electromagnetic stirring current is ≥400A, and the casting speed is between 0.5 -0.7m/min;

4. Wire rod rolling: the temperature of the double-entry module is controlled at 880-900°C, the spinning temperature is 900-920°C, the speed of the roller table is 0.2-0.4m/s, all the fans are turned off, and the heat preservation cover is turned off to ensure that the wire rod is at a lower temperature. A low-strength, large-grain-sized internal structure is obtained at a cooling rate.

The basic mechanism and the reason that the composition scope of the present invention is set are:

Carbon forms interstitial solid solution with iron in steel, which helps to increase the strength of steel. But from the point of view of wire rod electrical conductivity requirements, the requirements are as low as possible. Therefore, the carbon is controlled at 0.002% to 0.005%.

Most of silicon is dissolved in ferrite, which can improve the strength of steel, and at the same time has a deoxidation effect, which can eliminate the adverse effects of FeO inclusions on the quality of steel. From the perspective of the electrical conductivity of the wire rod, the silicon content is required to be as low as possible. Therefore, silicon is controlled at 0.004% to 0.010%.

Manganese has a good deoxidation effect, can remove FeO in steel, greatly improve the quality of steel, especially reduce the brittleness of steel, manganese can form MnS with sulfur, to eliminate the harmful effect of sulfur, and improve the processing performance of steel, so steel Must ensure a certain manganese content. At the same time, manganese also has the effect of solid solution strengthening. From the perspective of the electrical conductivity of the wire rod, it is necessary to control the manganese, so the manganese should be controlled at 0.05% to 0.15%.

Phosphorus and sulfur are both harmful impurity elements in steel. Phosphorus will precipitate Fe ₃ P with high brittleness in steel, which will increase the strength and brittleness of steel at room temperature, that is, increase the cold brittleness of steel. It is easy to segregate and difficult to eliminate. Sulfur hardly dissolves in iron, but forms FeS with iron, and FeS and Fe form eutectic with low melting point. During hot working, the eutectic distributed in the grain boundary is easy to melt and cause cracking, which increases the hot brittleness of steel. Because the electrical conductivity of the wire rod increases with the decrease of the impurity content in the steel, in order to ensure that the wire rod has good electrical conductivity, it is required that [P]≤0.015% and [S]≤0.010% in the steel, the lower the better.

Aluminum is generally used for deoxidation in steel, reducing the total oxygen content of steel, and at the same time has the effect of refining grains, mainly because aluminum forms fine and dispersed refractory compounds with other elements in steel to inhibit grain growth The effect is mainly the influence of AlN. Fine grains are unfavorable to the electrical conductivity of the wire rod, so the total aluminum content in the steel should be reduced; therefore, this patent controls the total aluminum content in the steel to ≤0.0050%.

The total oxygen content in the steel represents the cleanliness of the steel. An increase in the oxygen content will reduce the strength and plasticity of the steel. However, a too low total oxygen content requires an aluminum deoxidizer for strong deoxidation, so that the aluminum content in the molten steel is high, so that the disc The aluminum content of the rod is also high, and its grain refinement effect is remarkable, which improves the strength of the wire rod and reduces the electrical conductivity of the wire rod. Therefore, a certain oxygen content should be maintained in the wire rod, and the total oxygen content should be controlled at 0.0050% to 0.0080%.

The beneficial effects of the present invention are:

The present invention can control the grain size of the low-carbon steel wire rod at 20-40um, the electrical conductivity ≥ 15%, the tensile strength ≤ 300MPa, the surface shrinkage index ≥ 80%, and the low-carbon steel wire rod of the present invention can be made into conductive steel wire , can partially replace copper conductive materials, reduce production costs, and fully meet user requirements.

Detailed ways

The chemical composition wt% content of the ultra-low carbon steel wire rod for electric conduction in the present invention is: C 0.002%～0.005%, Si 0.004%～0.010%, Mn 0.05%～0.15%, P≤0.015%, S≤0.010%, total oxygen : 0.0050% ~ 0.0080%, all aluminum ≤ 0.0050%, the rest is iron and unavoidable but not higher than 0.1% impurities.

The production method of the ultra-low carbon steel wire rod for electric conduction is as follows: the carbon content of the steel produced by converter smelting is controlled at ≤0.040%, and the oxygen content of molten steel is controlled at 0.060%-0.070%. 2) RH refining is divided into two stages: the first stage adopts natural decarburization method, prohibits heating up and forced decarburization, the time is about 5-8min; The content is controlled at 0.030%-0.050%, and the reaction rate of carbon and oxygen is increased to reduce the carbon content below 0.0030%. It takes 15-20 minutes, and the temperature is adjusted to the requirements of continuous pouring. In order to prevent the ladle from adding carbon, low-carbon or carbon-free ladle is used for smelting. 3) The specification of continuous casting billet is 280×380mm, the superheat of molten steel in tundish is 25°C-30°C, the electromagnetic stirring current is 400-450A, and the casting speed is 0.5-0.7m/min; 4) The temperature of wire rod rolling into double modules is 880°C -900°C, spinning temperature 900°C-920°C, roller table speed 0.25-0.40m/s, fan and insulation cover are all closed, to ensure that the wire rod obtains low strength and large grain size at a low cooling rate, for high conductivity.

In the following, the present invention will be further described by taking a rolled wire rod with a diameter of Φ5.5mm as an example.

Embodiment wire rod chemical composition wt% content is as shown in table 1:

Table 1 Example wire rod chemical composition wt% content table

Example C Si mn P S o Al 1 0.0040 0.005 0.081 0.008 0.009 0.0076 0.0046 2 0.0045 0.007 0.110 0.010 0.008 0.0069 0.0041 3 0.0042 0.006 0.091 0.009 0.006 0.0072 0.0038 4 0.0039 0.007 0.101 0.011 0.007 0.0068 0.0045

Embodiment smelting, continuous casting and rolling production process parameters are as table 2:

Table 2 Example smelting, continuous casting production process parameter list

Embodiment rolling production process parameter is as table 3:

Table 3 embodiment rolling production process parameter list

Example Entering double module temperature ℃ Spinning temperature ℃ Roller speed m/s Fan, insulation cover 1 892 915 0.25 closure 2 884 908 0.25 closure 3 894 912 0.25 closure 4 885 906 0.25 closure

Grain size and performance test result after embodiment wire rod rolling are as table 4:

Table 4 Example wire rod rolled grain size and performance inspection results table

Example Grain sizeum Tensile strength MPa Area reduction % Conductivity % 1 20-40 278 85 15.5 2 20-40 286 84 15.3 3 20-40 292 83 15.2 4 20-40 282 84 15.4

Claims (2)

1. An ultra-low carbon steel wire rod for electric conduction, characterized in that its chemical composition wt% content is: C 0.002%～0.005%, Si 0.004%～0.010%, Mn 0.05%～0.15%, P≤0.015% , S ≤ 0.010%, total oxygen: 0.0050% ~ 0.0080%, total aluminum ≤ 0.0050%, the rest is iron and impurities not higher than 0.1%. 2. a production method of the described conduction ultra-low carbon steel wire rod of claim 1, is characterized in that, concrete method is: (1) Control the oxygen content and low carbon content of the molten steel before RH refining, control the carbon content of the converter smelting steel to ≤0.040%, and control the oxygen content of the molten steel to 0.060%-0.070%; (2), RH refining is divided into two stages: the first stage adopts natural decarburization method, prohibits heating and forced decarburization, and the time is 5-8 minutes; the second stage supplements the oxygen content in molten steel, blows oxygen with oxygen lance, and oxygen The content is controlled at 0.030%-0.050%, the reaction rate of carbon and oxygen is increased, the carbon content is reduced to below 0.0030%, the oxygen blowing time is 15-20 min, and the temperature is adjusted to the casting temperature, and low-carbon or carbon-free ladle is used for smelting ; (3) Continuous casting: Bloom protection casting is adopted, the cross-sectional size of the billet is 280×380mm, the superheat of molten steel in the tundish is ≤30°C, the electromagnetic stirring current is ≥400A, and the casting speed is between 0.5 -0.7m/min; (4) Wire rod rolling: the temperature of the double-entry module is controlled at 880-900°C, the spinning temperature is 900-920°C, the speed of the roller table is 0.2-0.4m/s, all the fans are turned off, and the heat preservation cover is turned off to ensure that the wire rod is kept at a relatively high temperature. A low-strength, large-grain-sized internal structure is obtained at a low cooling rate.