Steel for high-conductivity electrolytic aluminum steel claw and preparation method

Abstract

The invention provides steel for a high-conductivity electrolytic aluminum steel claw and a preparation method, and relates to the technical field of steel materials for production in the electrolytic aluminum industry. The steel comprises the following chemical components in percentage by mass: 0.01-0.05% of C, 0.055-0.095% of Ti, 0.08-0.18% of Cu, less than or equal to 0.007% of P, less than or equal to 0.006% of S and the balance of Fe and inevitable trace chemical elements. Wherein the C and the Ti simultaneously meet the relation that Ti / C is larger than or equal to 1.1 and smaller than or equal to 3.2. The steel for the high-conductivity electrolytic aluminum steel claw is prepared by regulating and controlling C, Ti and Cu, selecting low-cost raw materials, performing homogenizing heat treatment before hot rolling and performing stage control on rolling reduction in the hot rolling process; the method is simple and easy to operate, environmentally friendly, low in cost, short in process, high in efficiency, wide in application range and beneficial to industrial large-scale production and popularization.

Description

Technical Field

[0001] The present invention relates to the technical field of steel materials used in the production of electrolytic aluminum industry, and in particular to a high-conductivity steel for electrolytic aluminum steel claws and a preparation method thereof. Background Art

[0002] As a key structure in the production of electrolytic aluminum, the performance of the electrolytic aluminum anode steel claw directly affects the production efficiency and quality of electrolytic aluminum. It takes about 13,500 kWh of electricity to produce 1 ton of electrolytic aluminum, while the theoretical energy consumption per ton of aluminum is about 6,320 kWh, with an utilization rate of about 46.8%. The traditional anode steel claw steel has problems of insufficient strength and conductivity, which leads to deformation and fracture in high temperature and high current density working environment, increasing production costs and maintenance difficulties. Therefore, it is of great practical significance to develop a steel for electrolytic aluminum anode steel claw that has both high strength and high conductivity.

[0003] Chinese patent CN118371658A discloses a method for producing an anode steel claw, which prepares an internally highly dense, defect-free anode steel claw casting through smelting, steel purification, lost foam molding, pouring, and annealing heat treatment; however, the lost foam casting process easily causes carbon addition in the casting, and the distribution of carbon addition is irregular.

[0004] Chinese patent CN118957389A discloses a production method for improving the strength of industrial pure iron for electrolytic aluminum, which is prepared by desulfurized hot metal-converter-external refining-RH vacuum-continuous casting-ingot heating-high-pressure water dephosphorization-Ф850 ingot opening machine-Ф700mm×3+Ф550mm×4 continuous rolling mill group rolling-water cooling-sawing-straightening-inspection-grinding-bundling-warehousing-delivery. Although the strength index of industrial pure iron can be effectively improved through reasonable chemical composition design and production process, the production cost is relatively high due to the need to add micro-alloying elements such as rare earth elements, and its mechanical properties need to be improved.

[0005] Chinese patent CN117488014A discloses a method for treating molten steel for continuous casting of YT2 pure iron electrode flat steel slab for electrolytic aluminum. The method is prepared by molten steel entering LF station operation, slag making, RH deep decarburization, and Al control; although the content and state of C, Si and inclusions in molten steel can be effectively controlled, the production process has high requirements for deoxidation, and deoxidation materials such as aluminum particles are added, which will increase production costs.

[0006] Chinese patent CN103938080A discloses an inert alloy anode for electrolytic aluminum and a preparation method thereof, which has Fe and Cu as main components and also includes the addition of alloy elements such as Sn, Ni and Al, which can synergistically improve the oxidation resistance of the prepared material; however, the prepared material is directly obtained by melting and casting without machining and heat treatment, and the resistivity is about 67μΩ·cm, so the conductivity is poor.

[0007] Chinese patent CN102230189A discloses a nano-metal ceramic inert anode material for electrolytic aluminum and a preparation method thereof. The raw materials involve metal ceramic powders, and the prepared material is also a NiO-NiFe2O4 metal ceramic matrix. The added nano-powder is also a metal ceramic powder. Subsequently, pressing and sintering are required. Therefore, although the prepared material has good electrical conductivity at a high temperature of 1000°C, its mechanical properties are relatively poor. Summary of the invention

[0008] In order to solve the technical problems existing in the preparation process of steel for electrolytic aluminum steel claws in the prior art: 1) The chemical composition of steel is sensitive to performance requirements, and there are many types of added elements and strict ratios, which increases the production cost; and the smelting process needs to control the component content; 2) The strength and conductivity of the steel plate are low, resulting in a short service life of the steel claws; and the high temperature strength and conductivity are not considered; 3) The strength, conductivity and corrosion resistance of the steel plate cannot be improved synergistically. If one is improved, the other may be reduced, etc. The present invention proposes a high-conductivity steel for electrolytic aluminum steel claws and a preparation method that can solve the above-mentioned problems. The technical scheme is as follows:

[0009] A high-conductivity electrolytic aluminum steel claw steel, the chemical composition of the high-conductivity electrolytic aluminum steel claw steel is as follows by mass percentage: C 0.01-0.05%, Ti 0.055-0.095%, Cu 0.08-0.18%, P≤0.007%, S≤0.006%, and the rest is Fe and inevitable trace chemical elements; wherein the C and Ti simultaneously satisfy the relationship: 1.1≤Ti / C≤3.2.

[0010] Optionally, the microstructure of the steel matrix for the high-conductivity electrolytic aluminum steel claw is 96-98% by volume of ferrite and 2-4% by volume of pearlite, and further, 0.05-0.2% by volume of TiC precipitation phase is precipitated.

[0011] Optionally, the ferrite of the high-conductivity electrolytic aluminum steel claw steel is equiaxed in shape, with an average grain size of 15-70 μm; the pearlite is flaky in shape, with an average grain size of 5-20 μm; and the TiC precipitate phase is spherical in shape, with an average particle size of 5-20 nm.

[0012] Optionally, the room temperature properties of the steel for the high-conductivity electrolytic aluminum steel claws are as follows: tensile strength not less than 390 MPa, yield strength not less than 270 MPa, yield strength ratio of 0.65-0.75, elongation after fracture not less than 40%, and resistivity not higher than 12.5 μΩ·cm.

[0013] Optionally, the average particle size of the TiC precipitated phase is 90 nm.

[0014] A method for preparing the steel for the high-conductivity electrolytic aluminum steel claw is based on the above method, and the method for preparing the steel for the high-conductivity electrolytic aluminum steel claw comprises the following steps:

[0015] S1. Weighing raw materials: proportioning the raw materials according to the chemical composition content of the steel for the high-conductivity electrolytic aluminum steel claw, and then weighing each raw material to obtain weighed raw materials;

[0016] S2, smelting and casting: the raw materials weighed in S1 are smelted to obtain molten steel, and the chemical composition content of the molten steel is strictly controlled; after the smelting is completed, the molten steel is cast into a casting mold, cooled and solidified to form a casting;

[0017] S3, homogenization heat treatment: heating the S2 ingot to above the recrystallization temperature and keeping the temperature to obtain an ingot with uniform microstructure before hot rolling;

[0018] S4, hot rolling: hot rolling the ingot with uniform structure before S3 hot rolling, and air-cooling it to room temperature after rolling to obtain high conductivity electrolytic aluminum steel claw steel.

[0019] Optionally, the raw materials of S1 include iron ore, ferro-titanium alloy and copper.

[0020] Optionally, the S2 melting temperature is 1600-1650°C, the casting temperature is 1500-1550°C, and the ingot size is 200mm×200mm×6000mm.

[0021] Optionally, the temperature of S3 heated to above the recrystallization temperature is the preheating section temperature and the soaking section temperature, the preheating section temperature is controlled at ≤800°C, the soaking section temperature is controlled at 950-980°C, the total heating time is ≥180min, and the soaking section insulation time is ≥60min.

[0022] Optionally, the starting rolling temperature of S4 hot rolling is controlled at 920-960°C, the final rolling temperature is controlled at 860-900°C, and the total pressure vector is 55-70%.

[0023] The technical principle of selecting the chemical composition content of the present invention is:

[0024] The following is a detailed analysis and explanation of the functions and selection ranges of the components contained in the steel for the electrolytic aluminum steel claw of the present invention.

[0025] C: Carbon is the main strengthening element in steel. When C dissolves in Fe to form a solid solution, the strength and hardness of the steel are significantly improved. In addition, the C element makes the austenite grains more stable at high temperatures and less likely to grow. Therefore, a finer martensite structure can be obtained during quenching, thereby improving the hardenability of the steel. However, too high a C content will reduce the plasticity, toughness and weldability of the steel. In the present invention, the weight percentage of C is controlled to be 0.03-0.05%.

[0026] Ti: Titanium is a strong carbide-forming element. It combines with carbon in steel to form a stable dispersed distribution of TiC particles, thereby improving the strength and plasticity of the steel. The interaction between titanium atoms and iron atoms helps to conduct heat energy and thus improve thermal conductivity. Titanium also helps to form a dense oxide film and reduce the formation of easily corrosive phases. The weight percentage of Ti in the present invention is controlled to 0.055-0.095%.

[0027] Cu: Copper is a good conductive element, and its conductivity is second only to silver. Copper has a high thermal expansion coefficient, and adding it to steel can increase its thermal expansion coefficient. Copper can significantly improve the corrosion resistance of steel and form a dense oxide film on the surface of steel. In addition, copper can also inhibit local corrosion of steel, such as pitting and crevice corrosion. This is because the presence of copper can change the electrochemical properties of steel and make the corrosion current distribution more uniform. The present invention controls the weight percentage of Cu to 0.08-0.018%.

[0028] P, S: Phosphorus and sulfur are harmful impurity elements that are difficult to avoid in steel. P atoms will enter the grain boundaries of steel and destroy the strength of the grain boundaries, causing the steel to easily fracture brittlely when subjected to force or impact, especially when used under low temperature conditions, affecting the service life and reliability of the mold; S combines with the iron in the steel to form iron sulfide, which will be distributed along the grain boundaries, causing the toughness and plasticity of the steel to drop significantly. Therefore, the P and S contents in steel should be strictly limited. The present invention controls the weight percentage of the P element to ≤0.010%, and the weight percentage of the S element to ≤0.005%.

[0029] From the size description, we can know that the size of ferrite and pearlite is micron-sized, the precipitate phase is nanometer-sized, and the precipitate phase is distributed between crystals and within crystals. The volume proportion is calculated separately. The sum of the volume proportions of ferrite + pearlite is 100%.

[0030] Compared with the prior art, the above technical solution has at least the following beneficial effects:

[0031] The above scheme, the present invention proposes a high-conductivity steel for electrolytic aluminum steel claws and a preparation method, which can solve the technical problems existing in the prior art anode steel claws for electrolytic aluminum: 1) The chemical composition of steel is sensitive to performance requirements, and there are many types of added elements and strict ratios, which increases production costs; and the smelting process needs to control the component content; 2) The strength and conductivity of the steel plate are low, resulting in a short service life of the steel claws; and the high-temperature strength and conductivity are not considered; 3) The strength, conductivity and corrosion resistance of the steel plate cannot be improved synergistically. If one is improved, the other may be reduced, etc.

[0032] The present invention generates a precipitated phase through the synergistic effect of C, Ti and Cu, thereby reducing the carbon content in the crystal, and controls the size of the precipitated phase to reduce the influence on electron scattering, thereby ensuring its high electrical conductivity.

[0033] The present invention can form a dense oxide film on the steel surface through Ti and Cu, which significantly improves the corrosion resistance of the steel, thereby extending the service time of the steel claw in the electrolytic aluminum tank and reducing maintenance costs.

[0034] The present invention selects low-cost raw materials, performs homogenization heat treatment before hot rolling, and controls the rolling reduction during the hot rolling process, so that the prepared material can synergistically improve the mechanical properties, corrosion resistance, electrical conductivity and stability at room temperature and high temperature without the need for surface coating.

[0035] The room temperature properties of the steel for high-conductivity electrolytic aluminum steel claws prepared by the present invention are as follows: tensile strength is not less than 390MPa, yield strength is not less than 270MPa, yield strength ratio is 0.65-0.75, elongation after fracture is not less than 40%, and resistivity is not higher than 12.5μΩ·cm.

[0036] In summary, compared with other traditional methods, the method of the present invention prepares high-conductivity electrolytic aluminum steel claw steel by regulating C, Ti, Cu, low-cost raw material selection and homogenization heat treatment before hot rolling, and stage control of rolling reduction during hot rolling. The method is simple and easy to operate, green and environmentally friendly, low-cost, short process, high efficiency, wide application range, and is conducive to large-scale industrial production and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] Figure 1 This is a microstructure diagram of a steel for a high-conductivity electrolytic aluminum steel claw according to Example 1 of the present invention;

[0039] Figure 2 This is a microstructure diagram of a steel for high-conductivity electrolytic aluminum steel claws according to Example 2 of the present invention;

[0040] Figure 3 This is a microstructure diagram of a high-conductivity electrolytic aluminum steel claw steel according to Example 3 of the present invention. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0042] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0043] In the embodiments of the present invention, "image" and "picture" may sometimes be used interchangeably. It should be noted that when the distinction between them is not emphasized, the meanings they intend to express are consistent.

[0044] In the embodiments of the present invention, sometimes a subscript such as W1 may be written as a non-subscript such as W1. When the difference is not emphasized, the meanings to be expressed are the same.

[0045] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0046] A high-conductivity electrolytic aluminum steel claw steel, the chemical composition of the high-conductivity electrolytic aluminum steel claw steel is as follows by mass percentage: C 0.01-0.05%, Ti 0.055-0.095%, Cu 0.08-0.18%, P≤0.007%, S≤0.006%, and the rest is Fe and inevitable trace chemical elements; wherein the C and Ti simultaneously satisfy the relationship: 1.1≤Ti / C≤3.2.

[0047] In particular, the chemical composition of the steel for high-conductivity electrolytic aluminum steel claws is, by mass percentage, C 0.03-0.05%, Ti 0.060-0.075%, Cu 0.10-0.15%, P≤0.007%, S≤0.006%, and the rest is Fe and inevitable trace chemical elements; wherein, the C and Ti simultaneously satisfy the relationship: 1.2≤Ti / C≤2.5.

[0048] Particularly, the microstructure of the steel matrix for the high-conductivity electrolytic aluminum steel claw is 96-98% by volume of ferrite and 2-4% by volume of pearlite, and further, 0.05-0.2% by volume of TiC precipitate phase is precipitated.

[0049] Particularly, the ferrite of the high-conductivity electrolytic aluminum steel claw steel is equiaxed in shape, with an average grain size of 15-70 μm; the pearlite is flaky in shape, with an average grain size of 5-20 μm; and the TiC precipitate phase is spherical in shape, with an average particle size of 5-20 nm.

[0050] In particular, the room temperature properties of the steel for the high-conductivity electrolytic aluminum steel claw are as follows: tensile strength is not less than 390 MPa, yield strength is not less than 270 MPa, yield strength ratio is 0.65-0.75, elongation after fracture is not less than 40%, and resistivity is not higher than 12.5 μΩ·cm.

[0051] In particular, the average particle size of the TiC precipitated phase was 90 nm.

[0052] A method for preparing the steel for the high-conductivity electrolytic aluminum steel claw is based on the above method, and the method for preparing the steel for the high-conductivity electrolytic aluminum steel claw comprises the following steps:

[0053] S1. Weighing raw materials: proportioning the raw materials according to the chemical composition content of the steel for the high-conductivity electrolytic aluminum steel claw, and then weighing each raw material to obtain weighed raw materials;

[0054] S2, smelting and casting: the raw materials weighed in S1 are smelted to obtain molten steel, and the chemical composition content of the molten steel is strictly controlled; after the smelting is completed, the molten steel is cast into a casting mold, cooled and solidified to form a casting;

[0055] S3, homogenization heat treatment: heating the S2 ingot to above the recrystallization temperature and keeping the temperature to obtain an ingot with uniform microstructure before hot rolling;

[0056] S4, hot rolling: hot rolling the ingot with uniform structure before S3 hot rolling, and air-cooling it to room temperature after rolling to obtain high conductivity electrolytic aluminum steel claw steel.

[0057] In particular, the S1 raw materials include iron ore, ferro-titanium and copper.

[0058] In particular, the S2 melting temperature is 1600-1650°C, the casting temperature is 1500-1550°C, and the ingot size is 200mm×200mm×6000mm.

[0059] In particular, the temperature at which S3 is heated to a temperature above the recrystallization temperature is the preheating section temperature and the soaking section temperature, the preheating section temperature is controlled at ≤800°C, the soaking section temperature is controlled at 950-980°C, the total heating time is ≥180min, and the soaking section insulation time is ≥60min.

[0060] In particular, the starting rolling temperature of S4 hot rolling is controlled at 920-960°C, the final rolling temperature is controlled at 860-900°C, and the total pressure vector is 55-70%.

[0061] Example 1

[0062] A high-conductivity electrolytic aluminum steel claw steel, the chemical composition of the high-conductivity electrolytic aluminum steel claw steel is as follows by mass percentage: C 0.05%, Ti 0.063%, Cu 0.15%, P 0.005%, S 0.005%, and the rest is Fe and inevitable trace chemical elements; wherein the Ti / C is 1.26.

[0063] A method for preparing the steel for the high-conductivity electrolytic aluminum steel claw is based on the above method, and the method for preparing the steel for the high-conductivity electrolytic aluminum steel claw comprises the following steps:

[0064] S1. Weighing raw materials: proportioning the raw materials according to the chemical composition content of the steel for the high-conductivity electrolytic aluminum steel claw, and then weighing each raw material, including iron ore, ferrotitanium alloy and copper, to obtain weighed raw materials;

[0065] S2, smelting and casting: the weighed raw materials in S1 are smelted to obtain molten steel, the smelting temperature is 1610°C, the casting temperature is 1515°C, and the smelting temperature is 1515°C, and the slab is cooled and solidified to form a casting; the size of the casting is 200mm×200mm×6000mm;

[0066] S3, homogenization heat treatment: the S2 ingot is heated to a temperature above the recrystallization temperature and kept warm. The temperature above the recrystallization temperature is the preheating section temperature and the soaking section temperature. The preheating section temperature is controlled at 785°C, the soaking section temperature is controlled at 955°C, the total heating time is 185 minutes, and the soaking section holding time is 60 minutes, so as to obtain an ingot with a uniform microstructure before hot rolling.

[0067] S4, hot rolling: hot rolling is performed on the ingot with uniform organizational structure before S3 hot rolling. The starting rolling temperature of hot rolling is controlled at 947°C, the final rolling temperature is controlled at 891°C, the total pressure vector is 65%, and the ingot is air-cooled to room temperature after rolling to obtain high conductivity electrolytic aluminum steel claw steel.

[0068] The microstructure of the steel matrix for the high-conductivity electrolytic aluminum steel claw prepared in this embodiment is 96.3% by volume of ferrite and 3.7% by volume of pearlite, and in addition, there is a TiC precipitate phase with a total volume fraction of 0.16%.

[0069] like Figure 1 As shown, the ferrite of the high-conductivity electrolytic aluminum steel claw steel prepared in this embodiment has an equiaxed shape and an average grain size of 17 μm; the pearlite has a lamellar shape and an average grain size of 7.3 μm; the TiC precipitate phase has a spherical shape and an average particle size of 11 nm.

[0070] The room temperature properties of the high-conductivity electrolytic aluminum steel claw steel prepared in this embodiment are as follows: tensile strength is 412 MPa, yield strength is 283 MPa, yield strength ratio is 0.687, elongation after fracture is 44%, and resistivity is 11.5 μΩ·cm.

[0071] Example 2

[0072] A high-conductivity electrolytic aluminum steel claw steel, the chemical composition of the high-conductivity electrolytic aluminum steel claw steel is as follows by mass percentage: C 0.04%, Ti 0.070%, Cu 0.12%, P 0.004%, S 0.005%, and the rest is Fe and inevitable trace chemical elements; wherein the Ti / C is 1.75.

[0073] A method for preparing the steel for the high-conductivity electrolytic aluminum steel claw is based on the above method, and the method for preparing the steel for the high-conductivity electrolytic aluminum steel claw comprises the following steps:

[0074] S1. Weighing raw materials: proportioning the raw materials according to the chemical composition content of the steel for the high-conductivity electrolytic aluminum steel claw, and then weighing each raw material, including iron ore, ferrotitanium alloy and copper, to obtain weighed raw materials;

[0075] S2, smelting and casting: the weighed raw materials in S1 are smelted to obtain molten steel, the smelting temperature is 1630°C, the casting temperature is 1500°C, and the steel is cooled and solidified to form a casting billet; the size of the casting billet is 200mm×200mm×6000mm;

[0076] S3, homogenization heat treatment: the S2 ingot is heated to a temperature above the recrystallization temperature and kept warm. The temperature above the recrystallization temperature is the preheating section temperature and the soaking section temperature. The preheating section temperature is controlled at 790°C, the soaking section temperature is controlled at 960°C, the total heating time is 190 minutes, and the soaking section holding time is 65 minutes, so as to obtain the ingot with uniform microstructure before hot rolling;

[0077] S4, hot rolling: hot rolling is performed on the ingot with uniform organizational structure before S3 hot rolling. The starting rolling temperature is controlled at 938°C, the final rolling temperature is controlled at 879°C, the total pressure vector is 65%, and the ingot is air-cooled to room temperature after rolling to obtain high conductivity electrolytic aluminum steel claw steel.

[0078] The microstructure of the steel matrix for the high-conductivity electrolytic aluminum steel claw prepared in this embodiment is 97.5% by volume of ferrite and 2.5% by volume of pearlite, and in addition, there is a TiC precipitate phase with a total volume fraction of 0.12%.

[0079] like Figure 2 As shown, the ferrite of the high-conductivity electrolytic aluminum steel claw steel prepared in this embodiment has an equiaxed shape and an average grain size of 21 μm; the pearlite has a lamellar shape and an average grain size of 6.1 μm; the TiC precipitate phase has a spherical shape and an average particle size of 13 nm.

[0080] The room temperature properties of the high-conductivity electrolytic aluminum steel claw steel prepared in this embodiment are as follows: tensile strength is 395 MPa, yield strength is 277 MPa, yield strength ratio is 0.701, elongation after fracture is 43%, and resistivity is 12.3 μΩ·cm.

[0081] Comparative Example 1

[0082] A steel for electrolytic aluminum anode steel claws, the chemical composition of the steel for electrolytic aluminum anode steel claws is as follows by mass percentage: C 0.05%, Ti 0.049%, Cu 0.15%, P 0.006%, S 0.004%, and the rest is Fe and inevitable trace chemical elements; wherein the Ti / C is 0.98.

[0083] A method for preparing the steel for electrolytic aluminum anode steel claws based on the above method comprises the following steps:

[0084] S1. Weighing raw materials: proportioning the raw materials according to the chemical composition content of the steel for the electrolytic aluminum anode steel claw, and then weighing each raw material, including iron ore, ferrotitanium alloy and copper, to obtain weighed raw materials;

[0085] S2, smelting and casting: the weighed raw materials in S1 are smelted to obtain molten steel, the smelting temperature is 1670°C, and the chemical composition content of the molten steel is strictly controlled; after smelting, the molten steel is cast into a mold, the casting temperature is 1570°C, and cooled and solidified to form a cast billet; the size of the cast billet is 200mm×200mm×6000mm;

[0086] S3, homogenization heat treatment: heat the S2 ingot to a temperature above the recrystallization temperature and keep it warm. The temperature above the recrystallization temperature is the preheating section temperature and the soaking section temperature. The preheating section temperature is controlled at 795°C, the soaking section temperature is controlled at 955°C, the total heating time is 180 minutes, and the soaking section holding time is 60 minutes, so as to obtain the ingot with uniform microstructure before hot rolling;

[0087] S4, hot rolling: hot rolling is performed on the ingot with uniform organizational structure before S3 hot rolling. The starting rolling temperature is controlled at 941°C, the final rolling temperature is controlled at 884°C, the total pressure vector is 65%, and the ingot is air-cooled to room temperature after rolling to obtain high conductivity electrolytic aluminum steel claw steel.

[0088] The microstructure of the steel matrix for the high-conductivity electrolytic aluminum steel claw prepared in this comparative example is 96.7% by volume of ferrite and 3.3% by volume of pearlite, and in addition, there is a TiC precipitate phase with a total volume fraction of 0.15%.

[0089] The ferrite of the high-conductivity electrolytic aluminum steel claw steel prepared in this comparative example is equiaxed in shape, with an average grain size of 15 μm; the pearlite is lamellar in shape, with an average grain size of 7.7 μm; and the TiC precipitate phase is spherical in shape, with an average particle size of 21 nm.

[0090] The room temperature properties of the steel for electrolytic aluminum anode steel claws prepared in this comparative example are as follows: tensile strength is 372 MPa, yield strength is 243 MPa, yield strength ratio is 0.653, elongation after fracture is 39%, and resistivity is 12.8 μΩ·cm.

[0091] Comparative Example 2

[0092] A steel for electrolytic aluminum anode steel claws, the chemical composition of the steel for electrolytic aluminum anode steel claws is as follows by mass percentage: C 0.04%, Ti 0.68%, P 0.004%, S 0.006%, and the rest is Fe and inevitable trace chemical elements; wherein the Ti / C is 17.

[0093] A method for preparing the steel for electrolytic aluminum anode steel claws based on the above method comprises the following steps:

[0094] S1. Weighing raw materials: proportioning the raw materials according to the chemical composition content of the steel for the electrolytic aluminum anode steel claw, and then weighing each raw material, including iron ore, ferrotitanium alloy and copper, to obtain weighed raw materials;

[0095] S2, smelting and casting: the weighed raw materials in S1 are smelted to obtain molten steel, the smelting temperature is 1630°C, and the chemical composition content in the molten steel is strictly controlled; after smelting, the molten steel is cast into a mold, the casting temperature is 1550°C, and cooled and solidified to form a cast billet; the size of the cast billet is 200mm×200mm×6000mm;

[0096] S3, homogenization heat treatment: the S2 ingot is heated to a temperature above the recrystallization temperature and kept warm. The temperature above the recrystallization temperature is the preheating section temperature and the soaking section temperature. The preheating section temperature is controlled at 785°C, the soaking section temperature is controlled at 960°C, the total heating time is 185min, and the soaking section holding time is 65min, so as to obtain an ingot with a uniform microstructure before hot rolling.

[0097] S4, hot rolling: hot rolling is performed on the ingot with uniform organizational structure before S3 hot rolling. The starting rolling temperature is controlled at 944°C, the final rolling temperature is controlled at 887°C, the total pressure vector is 60%, and the ingot is air-cooled to room temperature after rolling to obtain high conductivity electrolytic aluminum steel claw steel.

[0098] The microstructure of the steel matrix for the high-conductivity electrolytic aluminum steel claw prepared in this comparative example is 96.9% by volume of ferrite and 3.1% by volume of pearlite, and in addition, there is a TiC precipitate phase with a total volume fraction of 0.03%.

[0099] The ferrite of the high-conductivity electrolytic aluminum steel claw steel prepared in this comparative example is equiaxed in shape, with an average grain size of 35 μm; the pearlite is lamellar in shape, with an average grain size of 7.2 μm; and the TiC precipitate phase is spherical in shape, with an average particle size of 15 nm.

[0100] The room temperature properties of the steel for electrolytic aluminum anode steel claws prepared in this comparative example are as follows: tensile strength is 384 MPa, yield strength is 270 MPa, yield strength ratio is 0.703, elongation after fracture is 43%, and resistivity is 13.6 μΩ·cm.

[0101] It can be seen that compared with Examples 1-2 of the present application, the test steel of Comparative Example 1, since its Ti content is lower than the requirements of the invention and Ti / C is also smaller than the range required by the invention, less TiC precipitation leads to a higher carbon content in the crystal, which has a greater impact on electron scattering and thus leads to a lower electrical conductivity than the requirements of the invention, and a poor precipitation strengthening effect. The room temperature tensile strength is 372 MPa and the yield strength is 243 MPa. Its mechanical properties are poor and do not meet the requirements of the invention.

[0102] The mechanical properties of the steel tested in Comparative Example 2 meet the performance requirements of the steel for electrolytic aluminum steel claws, but since Cu is not added to the composition, the addition of Cu in the steel can increase its thermal expansion coefficient. Since the content is lower than the invention requirement, its resistivity is 13.6μΩ·cm, which does not meet the invention requirement of the steel for electrolytic aluminum steel claws.

[0103] It can be seen from Table 3 that the test steels of Examples 1 and 2 have good mechanical properties, with yield strength ≥277 MPa, tensile strength ≥395 MPa, and elongation ≥43%, and have excellent comprehensive mechanical properties. The room temperature resistivity is ≤12.3 μΩ·cm, and the resistivity performance is excellent. In addition, the test steel has a low alloy content, a simple production process, and a low production cost, which meets the use requirements and has good economic benefits.

[0104] Example 3

[0105] A high-conductivity electrolytic aluminum steel claw steel, the chemical composition of the high-conductivity electrolytic aluminum steel claw steel is as follows by mass percentage: C 0.03%, Ti 0.070%, Cu 0.15%, P 0.027%, S 0.015%, and the rest is Fe and inevitable trace chemical elements; wherein the Ti / C is 2.33.

[0106] A method for preparing the steel for the high-conductivity electrolytic aluminum steel claw is based on the above method, and the method for preparing the steel for the high-conductivity electrolytic aluminum steel claw comprises the following steps:

[0107] S1. Weighing raw materials: proportioning the raw materials according to the chemical composition content of the steel for the high-conductivity electrolytic aluminum steel claw, and then weighing each raw material, including iron ore, ferrotitanium alloy and copper, to obtain weighed raw materials;

[0108] S2, smelting and casting: the weighed raw materials in S1 are smelted to obtain molten steel, the smelting temperature is 1610°C, the casting temperature is 1500°C, and the steel is cooled and solidified to form a casting billet; the size of the casting billet is 200mm×200mm×6000mm;

[0109] S3, homogenization heat treatment: the S2 ingot is heated to a temperature above the recrystallization temperature and kept warm. The temperature above the recrystallization temperature is the preheating section temperature and the soaking section temperature. The preheating section temperature is controlled at 780°C, the soaking section temperature is controlled at 950°C, the total heating time is 200min, and the soaking section holding time is 60min, so as to obtain an ingot with a uniform microstructure before hot rolling.

[0110] S4, hot rolling: hot rolling is performed on the ingot with uniform organizational structure before S3 hot rolling. The starting rolling temperature of hot rolling is controlled at 930°C, the final rolling temperature is controlled at 860°C, the total pressure vector is 60%, and the steel is air-cooled to room temperature after rolling to obtain high conductivity electrolytic aluminum steel claw steel.

[0111] The microstructure of the steel matrix for the high-conductivity electrolytic aluminum steel claw prepared in this embodiment is 97.7% by volume of ferrite and 2.3% by volume of pearlite, and in addition, there is a TiC precipitate phase with a total volume fraction of 0.18%.

[0112] like Figure 3As shown, the ferrite of the high-conductivity electrolytic aluminum steel claw steel prepared in this embodiment has an equiaxed shape and an average grain size of 16 μm; the pearlite has a lamellar shape and an average grain size of 8.6 μm; the TiC precipitate phase has a spherical shape and an average particle size of 7 nm.

[0113] The room temperature properties of the high-conductivity electrolytic aluminum steel claw steel prepared in this embodiment are as follows: tensile strength is 403 MPa, yield strength is 284 MPa, yield strength ratio is 0.705, elongation after fracture is 40%, and resistivity is 11.5 μΩ·cm.

[0114] Example 4

[0115] A high-conductivity electrolytic aluminum steel claw steel, the chemical composition of the high-conductivity electrolytic aluminum steel claw steel is as follows by mass percentage: C 0.04%, Ti 0.059%, Cu 0.11%, P 0.017%, S 0.023%, and the rest is Fe and inevitable trace chemical elements; wherein the Ti / C is 1.475.

[0116] A method for preparing the steel for the high-conductivity electrolytic aluminum steel claw is based on the above method, and the method for preparing the steel for the high-conductivity electrolytic aluminum steel claw comprises the following steps:

[0117] S1. Weighing raw materials: proportioning the raw materials according to the chemical composition content of the steel for the high-conductivity electrolytic aluminum steel claw, and then weighing each raw material, including iron ore, ferrotitanium alloy and copper, to obtain weighed raw materials;

[0118] S2, smelting and casting: the weighed raw materials in S1 are smelted to obtain molten steel, the smelting temperature is 1600°C, the casting temperature is 1520°C, and the smelting temperature is 1520°C, and the slab is cooled and solidified to form a casting; the size of the casting is 200mm×200mm×6000mm;

[0119] S3, homogenization heat treatment: heat the S2 ingot to a temperature above the recrystallization temperature and keep it warm. The temperature above the recrystallization temperature is the preheating section temperature and the soaking section temperature. The preheating section temperature is controlled at 750°C, the soaking section temperature is controlled at 980°C, the total heating time is 200 minutes, and the soaking section holding time is 70 minutes, so as to obtain an ingot with a uniform microstructure before hot rolling.

[0120] S4, hot rolling: hot rolling is performed on the ingot with uniform organizational structure before S3 hot rolling. The starting rolling temperature of hot rolling is controlled at 930°C, the final rolling temperature is controlled at 860°C, the total pressure vector is 65%, and the ingot is air-cooled to room temperature after rolling to obtain high conductivity electrolytic aluminum steel claw steel.

[0121] The microstructure of the steel matrix for the high-conductivity electrolytic aluminum steel claw prepared in this embodiment is 97.2% by volume of ferrite and 2.8% by volume of pearlite, and in addition, there is a TiC precipitate phase with a total volume fraction of 0.07%.

[0122] The ferrite of the high-conductivity electrolytic aluminum steel claw steel prepared in this embodiment is equiaxed in shape, with an average grain size of 28 μm; the pearlite is lamellar in shape, with an average grain size of 9.2 μm; the TiC precipitate phase is spherical in shape, with an average particle size of 14 nm.

[0123] The room temperature properties of the high-conductivity electrolytic aluminum steel claw steel prepared in this embodiment are as follows: tensile strength is 398 MPa, yield strength is 272 MPa, yield strength ratio is 0.683, elongation after fracture is 41%, and resistivity is 11.5 μΩ·cm.

[0124] Example 5

[0125] A high-conductivity electrolytic aluminum steel claw steel, the chemical composition of the high-conductivity electrolytic aluminum steel claw steel is as follows by mass percentage: C 0.05%, Ti 0.072%, Cu 0.13%, P 0.025%, S 0.017%, and the rest is Fe and inevitable trace chemical elements; wherein the Ti / C is 1.44.

[0126] A method for preparing the steel for the high-conductivity electrolytic aluminum steel claw is based on the above method, and the method for preparing the steel for the high-conductivity electrolytic aluminum steel claw comprises the following steps:

[0127] S1. Weighing raw materials: proportioning the raw materials according to the chemical composition content of the steel for the high-conductivity electrolytic aluminum steel claw, and then weighing each raw material, including iron ore, ferrotitanium alloy and copper, to obtain weighed raw materials;

[0128] S2, smelting and casting: the weighed raw materials in S1 are smelted to obtain molten steel, the smelting temperature is 1620°C, the casting temperature is 1520°C, and the smelting temperature is 1520°C, and the slab is cooled and solidified to form a casting; the size of the casting is 200mm×200mm×6000mm;

[0129] S3, homogenization heat treatment: the S2 ingot is heated to a temperature above the recrystallization temperature and kept warm. The temperature above the recrystallization temperature is the preheating section temperature and the soaking section temperature. The preheating section temperature is controlled at 780°C, the soaking section temperature is controlled at 950°C, the total heating time is 200min, and the soaking section holding time is 75min, so as to obtain an ingot with a uniform microstructure before hot rolling.

[0130] S4, hot rolling: hot rolling is performed on the ingot with uniform organizational structure before S3 hot rolling. The starting rolling temperature is controlled at 940°C, the final rolling temperature is controlled at 870°C, the total pressure vector is 65%, and the ingot is air-cooled to room temperature after rolling to obtain high conductivity electrolytic aluminum steel claw steel.

[0131] The microstructure of the steel matrix for the high-conductivity electrolytic aluminum steel claw prepared in this embodiment is 94.6% by volume of ferrite and 5.4% by volume of pearlite, and in addition, there is a TiC precipitate phase with a total volume fraction of 0.13%.

[0132] The ferrite of the high-conductivity electrolytic aluminum steel claw steel prepared in this embodiment is equiaxed in shape, with an average grain size of 23 μm; the pearlite is lamellar in shape, with an average grain size of 5.4 μm; the TiC precipitate phase is spherical in shape, with an average particle size of 17 nm.

[0133] The room temperature properties of the high-conductivity electrolytic aluminum steel claw steel prepared in this embodiment are as follows: tensile strength is 394 MPa, yield strength is 282 MPa, yield strength ratio is 0.716, elongation after fracture is 43%, and resistivity is 11.4 μΩ·cm.

[0134] Example 6

[0135] A high-conductivity electrolytic aluminum steel claw steel, the chemical composition of the high-conductivity electrolytic aluminum steel claw steel is as follows by mass percentage: C 0.02%, Ti 0.059%, Cu 0.12%, P 0.019%, S 0.019%, and the rest is Fe and inevitable trace chemical elements; wherein the Ti / C is 2.95.

[0136] A method for preparing the steel for the high-conductivity electrolytic aluminum steel claw is based on the above method, and the method for preparing the steel for the high-conductivity electrolytic aluminum steel claw comprises the following steps:

[0137] S1. Weighing raw materials: proportioning the raw materials according to the chemical composition content of the steel for the high-conductivity electrolytic aluminum steel claw, and then weighing each raw material, including iron ore, ferrotitanium alloy and copper, to obtain weighed raw materials;

[0138] S2, smelting and casting: the weighed raw materials in S1 are smelted to obtain molten steel, the smelting temperature is 1600°C, the casting temperature is 1510°C, and the smelting temperature is 1510°C, and the slab is cooled and solidified to form a casting; the size of the casting is 200mm×200mm×6000mm;

[0139] S3, homogenization heat treatment: the S2 ingot is heated to a temperature above the recrystallization temperature and kept warm, the temperature above the recrystallization temperature is the preheating section temperature and the soaking section temperature, the preheating section temperature is controlled at 800°C, the soaking section temperature is controlled at 970°C, the total heating time is 210min, the soaking section holding time is 80min, and the ingot with uniform microstructure before hot rolling is obtained;

[0140] S4, hot rolling: hot rolling is performed on the ingot with uniform organizational structure before S3 hot rolling. The starting rolling temperature of hot rolling is controlled at 930°C, the final rolling temperature is controlled at 860°C, the total pressure vector is 65%, and the ingot is air-cooled to room temperature after rolling to obtain high conductivity electrolytic aluminum steel claw steel.

[0141] The microstructure of the steel matrix for the high-conductivity electrolytic aluminum steel claw prepared in this embodiment is 97.9% by volume of ferrite and 2.1% by volume of pearlite, and in addition, there is a TiC precipitate phase with a total volume fraction of 0.09%.

[0142] The ferrite of the high-conductivity electrolytic aluminum steel claw steel prepared in this embodiment is equiaxed in shape, with an average grain size of 27 μm; the pearlite is lamellar in shape, with an average grain size of 11.5 μm; the TiC precipitate phase is spherical in shape, with an average particle size of 10 nm.

[0143] The room temperature properties of the high-conductivity electrolytic aluminum steel claw steel prepared in this embodiment are as follows: tensile strength is 390 MPa, yield strength is 274 MPa, yield strength ratio is 0.703, elongation after fracture is 43%, and resistivity is 11.1 μΩ·cm.

[0144] The above scheme, the present invention proposes a high-conductivity steel for electrolytic aluminum steel claws and a preparation method, which can solve the technical problems existing in the prior art anode steel claws for electrolytic aluminum: 1) The chemical composition of steel is sensitive to performance requirements, and there are many types of added elements and strict ratios, which increases production costs; and the smelting process needs to control the component content; 2) The strength and conductivity of the steel plate are low, resulting in a short service life of the steel claws; and the high-temperature strength and conductivity are not considered; 3) The strength, conductivity and corrosion resistance of the steel plate cannot be improved synergistically. If one is improved, the other may be reduced, etc.

[0145] The present invention generates a precipitated phase through the synergistic effect of C, Ti and Cu, thereby reducing the carbon content in the crystal, and controls the size of the precipitated phase to reduce the influence on electron scattering, thereby ensuring its high electrical conductivity.

[0146] The present invention can form a dense oxide film on the steel surface through Ti and Cu, which significantly improves the corrosion resistance of the steel, thereby extending the service time of the steel claw in the electrolytic aluminum tank and reducing maintenance costs.

[0147] The present invention selects low-cost raw materials, performs homogenization heat treatment before hot rolling, and controls the rolling reduction during the hot rolling process, so that the prepared material can synergistically improve the mechanical properties, corrosion resistance, electrical conductivity and stability at room temperature and high temperature without the need for surface coating.

[0148] The room temperature properties of the steel for high-conductivity electrolytic aluminum steel claws prepared by the present invention are as follows: tensile strength is not less than 390MPa, yield strength is not less than 270MPa, yield strength ratio is 0.65-0.75, elongation after fracture is not less than 40%, and resistivity is not higher than 12.5μΩ·cm.

[0149] In summary, compared with other traditional methods, the method of the present invention prepares high-conductivity electrolytic aluminum steel claw steel by regulating C, Ti, Cu, low-cost raw material selection and homogenization heat treatment before hot rolling, and stage control of rolling reduction during hot rolling. The method is simple and easy to operate, green and environmentally friendly, low-cost, short process, high efficiency, wide application range, and is conducive to large-scale industrial production and promotion.

[0150] It should be understood that the term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship, but it may also indicate an "and / or" relationship. Please refer to the context for specific understanding.

[0151] In the present invention, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0152] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0153] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A high-conductivity electrolytic aluminum steel claw steel, characterized in that: The chemical composition of the steel for high-conductivity electrolytic aluminum steel claws is as follows by mass percentage: C 0.01-0.05%, Ti 0.055-0.095%, Cu 0.08-0.18%, P≤0.007%, S≤0.006%, and the rest is Fe and inevitable trace chemical elements; wherein, the C and Ti simultaneously satisfy the relationship: 1.1≤Ti / C≤3.

2.

2. The high-conductivity electrolytic aluminum steel claw steel according to claim 1, characterized in that: The microstructure of the steel matrix for the high-conductivity electrolytic aluminum steel claw is 96-98% by volume of ferrite and 2-4% by volume of pearlite, and in addition, 0.05-0.2% by volume of TiC precipitation phase is precipitated.

3. The high-conductivity electrolytic aluminum steel claw steel according to claim 2, characterized in that: The ferrite of the high-conductivity electrolytic aluminum steel claw steel is equiaxed in shape, with an average grain size of 15-70 μm; the pearlite is flaky in shape, with an average grain size of 5-20 μm; and the TiC precipitated phase is spherical in shape, with an average particle size of 5-20 nm.

4. The high-conductivity electrolytic aluminum steel claw steel according to claim 1, characterized in that: The room temperature properties of the steel for the high-conductivity electrolytic aluminum steel claw are as follows: tensile strength is not less than 390 MPa, yield strength is not less than 270 MPa, yield strength ratio is 0.65-0.75, elongation after fracture is not less than 40%, and resistivity is not higher than 12.5 μΩ·cm.

5. A method for preparing high-conductivity electrolytic aluminum steel claw steel according to claim 1, characterized in that: The preparation method of the high-conductivity electrolytic aluminum steel claw steel comprises the following steps: S1. Weighing raw materials: proportioning the raw materials according to the chemical composition content of the steel for the high-conductivity electrolytic aluminum steel claw, and then weighing each raw material to obtain weighed raw materials; S2, smelting and casting: the raw materials weighed in S1 are smelted to obtain molten steel, and the chemical composition content of the molten steel is strictly controlled; after the smelting is completed, the molten steel is cast into a casting mold, cooled and solidified to form a casting; S3, homogenization heat treatment: heating the S2 ingot to above the recrystallization temperature and keeping the temperature to obtain an ingot with uniform microstructure before hot rolling; S4, hot rolling: hot rolling the ingot with uniform structure before S3 hot rolling, and air-cooling it to room temperature after rolling to obtain high conductivity electrolytic aluminum steel claw steel.

6. The method for preparing high-conductivity electrolytic aluminum steel claw steel according to claim 5, characterized in that: S1 raw materials include iron ore, ferro-titanium and copper.

7. The method for preparing high-conductivity electrolytic aluminum steel claw steel according to claim 5, characterized in that: The S2 melting temperature is 1600-1650℃, the casting temperature is 1500-1550℃, and the billet size is 200mm×200mm×6000mm.

8. The method for preparing high-conductivity electrolytic aluminum steel claw steel according to claim 5, characterized in that: The temperature of S3 heated to above the recrystallization temperature is the preheating section temperature and the soaking section temperature. The preheating section temperature is controlled at ≤800°C, the soaking section temperature is controlled at 950-980°C, the total heating time is ≥180min, and the soaking section insulation time is ≥60min.

9. The method for preparing high-conductivity electrolytic aluminum steel claw steel according to claim 5, characterized in that: The starting rolling temperature of S4 hot rolling is controlled at 920-960℃, the final rolling temperature is controlled at 860-900℃, and the total pressure vector is 55-70%.

Images