GB2610653A

GB2610653A - Low-aluminum and high-titanium welding wire steel and smelting method therefor.

Info

Publication number: GB2610653A
Application number: GB2113700.5A
Authority: GB
Inventors: Xiao Danping; Zhang Hua; Li Mengxiong
Original assignee: Jiangsu Yonggang Group Co Ltd
Current assignee: Jiangsu Yonggang Group Co Ltd
Priority date: 2020-10-22
Filing date: 2021-04-30
Publication date: 2023-03-15
Anticipated expiration: 2041-04-30
Also published as: GB202113700D0; GB2610653B

Abstract

The present invention provides a low-aluminum and high-titanium welding wire steel and a smelting method therefor. The method comprises the following steps: step S1, converter tapping, deoxidizing and alloying: adding high-silicon silicomanganese and high-purity ferrosilicon in sequence during converter tapping to carry out deoxidizing and alloying, and then adding lime and fluorite in sequence; and step S2, LF refining: adding lime and fluorite to an LF furnace according to the fluidity of refining slag; when energizing the refining for the first time, adding calcium carbide and ferrosilicon powder in multiple batches to deoxidize slag surfaces; carrying out sampling and testing after energizing for a period of time, and according to the test results, adding high-purity ferrosilicon and metal manganese to adjust the compositions to target values; from the addition of alloy to the end of the refining, adding ferrosilicon powder to maintain the reducibility of the refining slag; and in the later refining stage, feeding ferrotitanium wires at one time so that the titanium content reaches a target value, supplementing sulfur lines according to a sulfur content in the test results, and then performing continuous casting on a machine after soft blowing. The present invention stably controls the compositions of the low-aluminum and high-titanium welding wire steel, also greatly improves the continuous casting performance of the low-aluminum and high-titanium welding wire steel, and reduces production cost.

Description

LOW-ALUMINUM AND HIGH-TITANIUM WELDING WIRE STEEL AND SMELTING

PROCESS THEREOF

Technical Field

100011 The present invention belongs to the technical field of steel smelting, and in particular relates to a low-aluminum and high-titanium welding wire steel and a smelting process thereof

Background

100021 With the constantly-increasing quality requirements for steel products, the quality requirements for welding wires have also increased. There are very strict requirements on a composition of welding wire steel, which results in difficult control of smelting of welding wire steel. Titanium-containing welding steel is obtained by adding titanium and other elements on the basis of ordinary welding steel, which can reduce the spattering during a welding process, makes a weld metal have prominent plasticity and toughness, and leads to stable and mild welding arcs and nice-looking welding seams.

100031 The higher the titanium content in the titanium-containing welding wire steel, the better the welding performance of the welding wire, but the larger the smelting difficulty. Especially in the case of low carbon and aluminum contents, there are mainly the following problems in a smelting process: 1) A carbon content in the smelting process needs to be controlled at a low level, and a carbon content in a finished product needs to be controlled at 0.05% to 0.07%, but the addition of an alloy in converter tapping and the increase in a refining temperature will increase a carbon content in molten steel. 2) With strong metallicity, titanium is easily oxidized during a smelting process, and thus a titanium yield is low and unstable. Especially in the case of low-aluminum control, molten steel is deoxidized only by silicomanganese, and thus it is difficult to stably control a titanium content. 3) As titanium is easily oxidized, titanium oxide inclusions are easy to accumulate in a nozzle and a stopper during a continuous casting process, thereby causing nodulation on the nozzle and stopper and thus causing failed continuous production. At present, welding wire steel with a titanium content of 0.20% is mainly produced by die casting, and the continuous casting production has very poor castability, which generally achieves 2 to 4 continuous casting heats and is difficult to stably achieve 5 or more continuous casting heats.

100041 CN103045946A (publication date: 20130417) discloses a high-titanium alloy welding wire steel arid a manufacturing process thereof. In the manufacturing process, rare earth elements are added to inhibit the titanium oxidation of the welding wire steel during continuous casting and welding, thereby controlling a titanium content at < 0.18% and an aluminum content at < 0.10% in a finished product. As the rare earth elements added in this method are expensive, a cost of steelmaking is increased. Moreover, the welding wire steel produced by this method has a low titanium content of 0.15% to 0.18%; and ferroaluminum is added during tapping for deep deoxidation, and thus there is a high aluminum content in a production process and a finished product, which fails to achieve low-aluminum control.

Summary

[0005] In view of the above technical problems, the present invention provides a low-aluminum and high-titanium welding wire steel and a smelting process thereof. The smelting process is simple and easily-controlled, which realizes the stable control of a composition of the low-aluminum and high-titanium welding wire steel, greatly improves the continuous casting performance of the low-aluminum and high-titanium welding wire steel, and reduces a production cost.

[0006] The present invention is realized through the following technical solution. A smelting process of a low-aluminum and high-titanium welding wire steel is provided, including the following steps: step Si. converter tapping, deoxidation, and alloying: at the end of converter smelting, controlling a carbon content in molten steel at < 0.04% and a temperature of the molten steel at > 1,600°C; and when converter tapping is conducted, sequentially adding high-silicon silicomanganese and high-purity ferrosilicon for deoxidation and alloying, and sequentially adding lime and fluorite; wherein the high-silicon silicomanganese has a carbon content of < 0.3%, a silicon content of 25.0% to 28.0%, and a manganese content of 60.0% to 67.0%; the high-purity ferrosilicon has an aluminum content of < 0.03%, a carbon content of < 0.05%, and a silicon content of > 75.0%; and after the tapping is completed, in the molten steel, a silicon content is controlled at 0.70% to 0.80%, a manganese content is controlled at 1.35% to 1.45%, and a total aluminum content is controlled at <0.004%; and step 52. ladle furnace (LF) refining: in an early refining stage, adding lime and fluorite to the LF based on the flowability of a refining slag to ensure that the refining slag has prominent flowability; during first energization for refining, adding calcium carbide and ferrosilicon powder in multiple batches for deoxidation at a slag surface, during which an argon flow rate is controlled at 120 NL/min to 180 NL/min; after the energization is conducted for a specified time period (preferably for 12 min to 17 min), collecting samples for testing, and according to testing results, adding high-purity ferrosilicon and metal manganese to adjust a composition to a target value, wherein the metal manganese has a carbon content of < 0.05% and a manganese content of > 96.5%; after the alloy is added and before the refining is finished, adding ferrosilicon powder to maintain the reducibility of the refining slag, during which an argon flow rate is controlled at 40 NL/min to 80 NL/min; in a later refining stage, feeding a ferrotitanium wire at a time to make a titanium content reach a target value; according to a tested sulfur content, adding an appropriate amount of a sulfur wire, and conducting soft-blowing, during which an argon flow rate is controlled at 15 NL/min to 25 NL/min; and after the soft-blowing is conducted for 5 min to 10 mm, conducting continuous casting on a machine; wherein the ferrotitanium wire has an aluminum content of < 0.6% and a titanium content of 65.0% to 75.0%, casting is started by a ladle within 15 min to 20 min after the ferrotitanium wire is fed, and a superheat degree is 35°C to 50°C after a number of continuous casting heats are achieved to ensure the casting performance of the molten steel.

[0007] In the above solution, in the step SI, during the converter tapping, the lime is added at a total amount of 7.0 kg to 8.0 kg per ton of the molten steel, and the fluorite is added at a total amount of 2.0 kg to 2.5 kg per ton of the molten steel.

[0008] In the above solution, in the step Si, at 1/3 of the converter tapping, the high-silicon silicomanganese and the high-purity ferrosilicon are sequentially added for deoxidation and alloying, and then the lime and the fluorite are sequentially added to prevent the alloy auxiliary material added prematurely from agglomerating at a bottom.

[0009] In the above solution, in the step S2, during the refining, the lime is added at a total amount of 0 kg to 2.0 kg per ton of the molten steel, and the fluorite is added at a total amount of 0 kg to 1.0 kg per ton of the molten steel.

[0010] In the above solution, in the step S2, after the energizat on is conducted for 15 mm, samples are collected for testing.

[0011] In the above solution, in the step S2, in an early refining stage, a slag formation time is < 15 min; during the first energization for refining, the calcium carbide is added at a total amount of 0.2 kg to 0.4 kg per ton of the molten steel, and the ferrosilicon powder is added at a total amount of 1.2 kg to 1.6 kg per ton of the molten steel; and after the alloy is added and before the refining is finished, the ferrosilicon powder is added at a total amount of 0.4 kg to 0.6 kg per ton of the molten steel.

[0012] In the above solution, in the step S2, after the alloy is added and before the refining is finished, the ferrosilicon powder is added at a total amount of 0.4 kg to 0.6 kg per ton of the molten steel.

[0013] A low-aluminum and high-titanium welding wire steel produced by the smelting process of the low-aluminum and high-titanium welding wire steel is also provided, including the following chemical components in weight percentage: C: 0.05% to 0.07%, Si: 0.80% to 0.90%, Mn: 1.48% to 1.55%, P: < 0.018%, S: 0.008% to 0.012%, Ti: 0.18% to 0.23%, Al: < 0.007%, Ca: < 0.0010%, and Fe and inevitable impurities: the balance.

[0014] Compared with the prior art, the present invention has the following beneficial effects. The smelting process of the present invention can stably control a carbon content at 0.05% to 0.07%, an aluminum content at < 0.007%, a sulfur content at 0.008% to 0.012%, and a titanium content at 0.18% to 0.23%. The present invention optimizes the feeding mode and timing of the ferrotitanium wire by feeding the ferrotitanium wire at a time in the later refining stage, such that the nodulation on a nozzle and a stopper is avoided, the number of continuous casting heats can reach 16, and a rolled material has an oxygen content controlled at < 20 ppm and an average oxygen content of 15 ppm. The present invention provides a simple and easily-controlled smelting process, which realizes the stable control of a composition of the low-aluminum and high-titanium welding wire steel, greatly improves the continuous casting performance of the low-aluminum and high-titanium welding wire steel, and reduces a production cost. The devices involved in the present invention are all conventional devices for high-quality steel smelting in a converter, which further reduces a production cost.

Detailed Description of the Embodiment

100151 The examples of the present invention are described in detail below.

[0016] Example 1:

A smelting process of a low-aluminum and high-titanium welding wire steel was provided, including the following steps.

1) 50 t top and bottom combined blown converter tapping: A molten steel volume was 54.3 t, and at the end of converter smelting, a C content was 0.035%, a P content was 0.008%, and a temperature was 1,623°C. After 1/3 of tapping, 1,167 kg of high-silicon silicomanganese, 178 kg of high-purity ferrosilicon, 402 g of lime, and 103 kg of fluorite were sequentially added. A tapping time was 2 min and 25 s. Argon was continuously introduced during the tapping. After the tapping was completed, in molten steel, a silicon content was 0.77%, a manganese content was 1.40%, and an aluminum content was 0.0019%.

[0017] 2) LF refining: 98 kg of lime was added during refining. During first energization for refining, 20 kg of calcium carbide and 60 kg of ferrosilicon powder were added in multiple batches for deoxidation at a slag surface, during which an argon flow rate was controlled at 120 NL/min to 180 NL/min; after the energization was conducted for 15 mm, samples were collected for testing, and according to testing results, 42 kg of high-purity ferrosilicon and 75 kg of metal manganese were added to adjust a composition to a target value; after the alloy was added and before the refining was finished, 30 kg of ferrosilicon powder was added to maintain the reducibility of the refining slag, during which an argon flow rate was controlled at 40 NL/min to 80 NL/min; after the refining was completed, 770 m of a ferrotitanium wire was fed at a time to make a titanium content reach a target value, and then soft-blowing was conducted; according to a tested sulfur content, 13 m of a sulfur wire was added, during which an argon flow rate was controlled at 15 NL/min to 25 NL/min, and after the soft-blowing was conducted for 7 min, continuous casting was conducted on a machine, with a discharge temperature of 1,577°C. Casting was started by a ladle 15 min after the ferrotitanium wire was fed, and after 12 continuous casting heats were conducted, a superheat degree was 35°C.

[0018] 3) An obtained low-aluminum and high-titanium welding wire steel included the following chemical components in weight percentage: C: 0.07%, Si: 0.88%, Mn: 1.54%, P: 0.009%, S: 0.010%, Ti: 0.18%, Al: 0.005%, Ca: 0.0002%, and Fe and inevitable impurities: the balance; a rolled material had an oxygen content of 18 ppm; and the number of continuous casting heats in this example reached 15.

[0019] Example 2:

1) 50 t top and bottom combined blown converter tapping: A molten steel volume was 55.55 t, and at the end of converter smelting, a C content was 0.026%, a P content was 0.014%, and a temperature was 1624°C. After 1/3 of tapping, 1,178 kg of high-silicon silicomanganese, 164 kg of high-purity ferrosilicon, 402 kg of lime, and 102 kg of fluorite were sequentially added. A tapping time was 2 min and 17 s. Argon was continuously introduced during the tapping. After the tapping was completed, in molten steel, a silicon content was 0.75%, a manganese content was 1.39%, and an aluminum content was 0.0026%.

[0020] 2) LF refining: 114 kg of lime was added during refining. During first energization for refining, 20 kg of calcium carbide and 60 kg of ferrosilicon powder were added in multiple batches for deoxidation at a slag surface, during which an argon flow rate was controlled at 120 NL/min to 180 NL/min; after the energization was conducted for 15 min, samples were collected for testing, and according to testing results, 20 kg of high-purity ferrosilicon and 55 kg of metal manganese were added to adjust a composition to a target value; after the alloy was added and before the refining was finished, 30 kg of ferrosilicon powder was added to maintain the reducibility of the refining slag, during which an argon flow rate was controlled at 40 NL/min to 80 NL/min; after the refining was completed, 906 m of a ferrotitanium wire was fed at a time to make a titanium content reach a target value, and then soft-blowing was conducted; according to a tested sulfur content, 25 m of a sulfur wire was added, during which an argon flow rate was controlled at 15 NL/min to 25 NL/min, and after the soft-blowing was conducted for 9 min, continuous casting was conducted on a machine, with a discharge temperature of 1,580°C. Casting was started by a ladle 18 min after the ferrotitanium wire was fed, and after 8 continuous casting heats were conducted, a superheat degree was 40°C.

[0021] 3) An obtained low-aluminum and high-titanium welding wire steel included the following chemical components in weight percentage: C: 0.06%, Si: 0.87%, Mn: 1.52%, P: 0.015%, S: 0.009%, Ti: 0.22%, Al: 0.005%, Ca: 0.0003%, and Fe and inevitable impurities: the balance; a rolled material had an oxygen content of 15 ppm; and the number of continuous casting heats in this example reached 16.

[0022] Example 3:

1) 50 t top and bottom combined blown converter tapping: A molten steel volume was 54.90 t, and at the end of converter smelting, a C content was 0.029%, a P content was 0.012%, and a temperature was 1,633°C. After 1/3 of tapping, 1,164 kg of high-silicon silicomanganese, 169 kg of high-purity ferrosilicon, 410 kg of lime, and 103 kg of fluorite were sequentially added. A tapping time was 2 min and 16 s. Argon was continuously introduced during the tapping. After the tapping was completed, in molten steel, a silicon content was 0.71%, a manganese content was 1.35%, and an aluminum content was 0.0035%.

[0023] 2) LF refining: 159.87 kg of lime was added during refining. During first energization for refining, 20 kg of calcium carbide and 70 kg of ferrosilicon powder were added in multiple batches for deoxidation at a slag surface, during which an argon flow rate was controlled at 120 NL/min to 180 NL/min; after the energization was conducted for 15 min, samples were collected for testing, and according to testing results, 45 kg of high-purity ferrosilicon and 70 kg of metal manganese were added to adjust a composition to a target value; after the alloy was added and before the refining was finished, 30 kg of ferrosilicon powder was added to maintain the reducibility of the refining slag, during which an argon flow rate was controlled at 40 NL/min to 80 NL/min; after the refining was completed, 900 m of a ferrotitanium wire was fed at a time to make a titanium content reach a target value, and then soft-blowing was conducted; according to a tested sulfur content, 20 m of a sulfur wire was added, during which an argon flow rate was controlled at 15 NL/min to 25 NL/min; and after the soft-blowing was conducted for 8 min, continuous casting was conducted on a machine, with a discharge temperature of 1,588°C. Casting was started by a ladle 19 min after the ferrotitanium wire was fed, and after 3 continuous casting heats were conducted, a superheat degree was 48°C.

[0024] 3) An obtained low-aluminum and high-titanium welding wire steel included the following chemical components in weight percentage: C: 0.05%, Si: 0.82%, Mn: 1.51%, P: 0.014%, S: 0.008%, Ti: 0.23%, Al: 0.006%, Ca: 0.0003%, and Fe and inevitable impurities: the balance; a rolled material had an oxygen content of 18 ppm; and the number of continuous casting heats in this example reached 16.

[0025] Example 4:

A smelting process of a low-aluminum and high-titanium welding wire steel was provided, including the following steps: 1) 50 t top and bottom combined blown converter tapping: A molten steel volume was 51.2 t, and at the end of converter smelting, a C content was 0.031%, a P content was 0.012%, and a temperature was 1,623°C. After 1/3 of tapping, 1,163 kg of high-silicon silicomanganese, 196 kg of high-purity ferrosilicon, 402 kg of lime, and 101 kg of fluorite were sequentially added. A tapping time was 3 min. Argon was continuously introduced during the tapping. After the tapping was completed, in molten steel, a silicon content was 0.80%, a manganese content was 1.45%, and an aluminum content was 0.0031%.

[0026] 2) LF refining: 106 kg of lime and 36 kg of fluorite were added during refining. During first energization for refining, 20 kg of calcium carbide and 60 kg of ferrosilicon powder were added in multiple batches for deoxidati on at a slag surface, during which an argon flow rate was controlled at 120 NL/min to 180 NL/min; after the energization was conducted for 15 mm, samples were collected for testing, and according to testing results, 10 kg of high-purity ferrosilicon and 15 kg of metal manganese were added to adjust a composition to a target value; after the alloy was added and before the refining was finished, 40 kg of ferrosilicon powder was added to maintain the reducibility of the refining slag, during which an argon flow rate was controlled at 40 NL/min to 80 NL/min; after the refining was completed, 840 m of a ferrotitanium wire was fed at a time to make a titanium content reach a target value, and then soft-blowing was conducted; according to a tested sulfur content, 23 m of a sulfur wire was added, during which an argon flow rate was controlled at 15 NL/min to 25 NL/min; and after the soft-blowing was conducted for 8 min, continuous casting was conducted on a machine, with a discharge temperature of 1,592°C. Casting was started by a ladle 20 min after the ferrotitanium wire was fed, and after 9 continuous casting heats were conducted, a superheat degree was 50°C.

[0027] 3) An obtained low-aluminum and high-titanium welding wire steel included the following chemical components in weight percentage: C: 0.06%, Si: 0.89%, Mn: 1.50%, P: 0.013%, S: 0.008%, Ti: 0.22%, Al: 0.007%, Ca: 0.0003%, and Fe and inevitable impurities: the balance; a rolled material had an oxygen content of 14 ppm; and the number of continuous casting heats in this example reached 15.

[0028] It should be understood that although this specification is described in accordance with the examples, not every example only includes one independent technical solution. This description of the specification is for the sake of clarity only. Those skilled in the art should take the specification as a whole, and the technical solutions in examples can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

[0029] The series of detailed description listed above are only specific illustration of feasible examples of the present invention, rather than limiting the claimed scope of the present invention All equivalent examples or changes made without departing from the technical spirit of the present invention should be included in the claimed scope of the present invention.

Claims

Claims What is claimed is: 1. A smelting process of a low-aluminum and high-titanium welding wire steel, characterized in that the low-aluminum and high-titanium welding wire steel comprises the following chemical components in weight percentage: C: 0.05% to 0.07%, Si: 0.80% to 0.90%, Mn: 1.48% to 1.55%, P: < 0.018%, S: 0.008% to 0.012%, Ti: 018% to 0.23%, Al: < 0.007%, Ca: <0.0010%, and Fe and inevitable impurities: the balance; and the smelting process comprises the following steps: step Si. converter tapping, deoxidation, and alloying: at an end of converter smelting, controlling a carbon content in molten steel at < 0.04% and a temperature of the molten steel at > 1,600°C; and when the converter tapping is conducted, sequentially adding high-silicon silicomanganese and high-purity ferrosilicon for the deoxidation and alloying, and sequentially adding lime and fluorite; wherein the high-silicon silicomanganese has a carbon content of < 0.3%, a silicon content of 25.0% to 28.0%, and a manganese content of 60.0% to 67.0%; the high-purity ferrosilicon has an aluminum content of < 0.03%, a carbon content of < 0.05%, and a silicon content of > 75.0%; the lime is added at a total amount of 7.0 kg to 8.0 kg per ton of the molten steel and the fluorite is added at a total amount of 2.0 kg to 2.5 kg per ton of the molten steel; and after the converter tapping is completed, in the molten steel, a silicon content is controlled at 0.70% to 0.80%, a manganese content is controlled at 1.35% to 1.45%, and a total aluminum content is controlled at <0.004%; and step 52. ladle furnace (LF) refining: in an early refining stage, adding lime and fluorite to the LF according to the flowability of a refining slag, wherein a slag formation time is < 15 mm; during first energization for refining, adding calcium carbide and ferrosilicon powder in multiple batches for deoxidation at a slag surface, during which an argon flow rate is controlled at 120 NL/min to 180 NL/min, wherein the calcium carbide is added at a total amount of 0.2 kg to 0.4 kg per ton of the molten steel and the ferrosilicon powder is added at a total amount of 1.2 kg to 1.6 kg per ton of the molten steel; after the energization is conducted for 12 min to 17 min, collecting samples for testing, and according to testing results, adding high-purity ferrosilicon and metal manganese to adjust a composition to a target value, wherein the metal manganese has a carbon content of < 0.05% and a manganese content of > 96.5%; after the alloy is added and before the refining is finished, adding ferrosilicon powder to maintain the reducibility of the refining slag, during which an argon flow rate is controlled at 40 NL/min to 80 NL/min; in a later refining stage, feeding a fen-otitanium wire at a time to make a titanium content reach a target value; according to a tested sulfur content, adding an appropriate amount of a sulfur wire, and conducting soft-blowing, during which an argon flow rate is controlled at 15 NL/min to 25 NL/min; and after the soft-blowing is conducted for 5 mm to 10 mm, conducting continuous casting on a machine; wherein the ferrotitanium wire has an aluminum content of < 0.6% and a titanium content of 65.0% to 75.0%, casting is started by a ladle within 15 min to 20 min after the ferrotitanium wire is fed, and a superheat degree is 35°C to 50°C after a number of continuous casting heats are achieved.
2. The smelting process of the low-aluminum and high-titanium welding wire steel according to claim 1, characterized in that in the step S 1, at 1/3 of the converter tapping, the high-silicon silicomanganese and the high-purity ferrosilicon are sequentially added for the deoxidation and alloying, and then the lime and the fluorite are sequentially added.
3. The smelting process of the low-aluminum and high-titanium welding wire steel according to claim 1, characterized in that in the step S2, during the refining, the lime is added at a total amount of 0 kg to 2.0 kg per ton of the molten steel, and the fluorite is added at a total amount of 0 kg to 1.0 kg per ton of the molten steel.
4. The smelting process of the low-aluminum and high-titanium welding wire steel according to claim 1, characterized in that in the step S2, after the energization is conducted for 15 min, samples are collected for testing.
5. The smelting process of the low-aluminum and high-titanium welding wire steel according to claim 1, characterized in that in the step S2, after the alloy is added and before the refining is finished, the ferrosilicon powder is added at a total amount of 0.4 kg to 0.6 kg per ton of the molten steel.