RU2538226C1 - Flux cored wire obtaining method - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: tubular blank is filled with a mix consisting of grains of fluxing stone powder and grains of modifying components with the mass contents 5-40% from grains of fluxing stone powder. The strength of grains of modifying components is selected 30% less than the strength of grains of fluxing stone powder. Before deforming the tubular blank is sealed. The tubular blank is deformed with decrease of its diameter down to the size corresponding to the following relation: $$\frac{D}{d}=10-500,$$

where D - diameter of the tubular blank, d - outside diameter of the flux cored wire, meanwhile the tubular blank before deforming is sealed.

EFFECT: improvement of quality of the flux cored wire by achieving of uniformity of density of the powder filler along the length of the flux cored wire and improvement of properties of the flux cored wire due to forming in the powder filler of nano-sized grains of modifying components.

Description

The invention relates to metallurgical engineering, and in particular to a method for producing flux-cored wire with an increased density of powder filler.

A known method of producing flux-cored wire (RF patent No. 2488473, IPC ⁸ B23K 35/40, B22F 5/12, publ. 07.27.2013). The wire is formed from a metal strip of a U-shaped profile with simultaneous filling with a powder filler with leveling and pre-compaction on a vibrating type device. A closed tubular shell profile with a fold lock is formed and reduction is carried out in a double three-roller die. In the first group of rollers, three deep corrugations are formed, providing a reduction in the cross-section of the profile up to 20%, while one of the corrugations is located in close proximity to the rebate lock. In the second group of rollers shifted by 60 ° along the molding axis relative to the first, the profile is calibrated with simultaneous compression of the three formed corrugations and the possibility of reducing the profile cross section to 25%. Provides an increase in the density of the filler wire, the uniformity of its distribution in the transverse and longitudinal direction and improving the quality of the wire.

A disadvantage of the known technical solution is the complexity of the process.

The closest technical solution is JP patent No. 2742957, IPC ⁶ B23K 35/40, B22F 5/12, publ. 03/28/1990. A method of manufacturing a flux-cored wire is that a mixture consisting of flux powder (80%) and metal powder (≤25%) is poured into a welded steel tube, which is annealed at a temperature of 650-850 ° C for 10 min and subjected drawing, reducing the diameter. The starting flux materials are granulated and dried, and then calcined at a temperature of ≈300 ° C.

The disadvantage of the closest technical solution is the lack of quality due to the inability to obtain an increased density of powder filler in the initial and final sections of the flux-cored wire due to the lack of sealing of the welded steel tube before drawing in the powder filler.

The objective of the proposed technical solution is to improve the quality of the wire by obtaining uniformity of the density of the powder filler along the length of the powder wire and improving the properties of the powder wire due to the formation of nanosized grains of modifying components in the powder filler.

The essence of the method for producing flux-cored wire is that the mixture consisting of flux powder is poured into the tubular billet, the tubular billet is deformed to reduce the diameter, and grains of modifying components with a mass content of 5-40% from flux powder grains and select grain strength of modifying components 30% less than flux powder grain strength, seal the tubular billet before deformation, deform the tubular billet, reducing the diameter to elichiny corresponding to the following relationship:

, $$\frac{D}{d}=10-500$$

,

where D is the diameter of the tube billet, d is the outer diameter of the cored wire.

A method of producing a cored wire is as follows. A mixture of grains of flux powder is taken and grains of modifying components are added to it, having a strength 30% less than the strength of flux powder grains, with a mass content of grains of modifying components of 5-40% of flux powder grains. This mixture, forming the core of the cored wire, is poured into a tubular billet (welded steel tube). The tubular billet is sealed and subjected to deformation with a decrease in diameter, at which the grinding of the grains of the powder mixture that make up the core of the flux-cored wire occurs. When crimping flux-cored wire, the grains of the powder of the core of the flux-cored wire are compressed. As a result of compression, the grains of the core of the cored wire, in which stresses exceeding the tensile strength arise, are crushed. When grinding the grains of the core of the flux cored wire, grains with sizes less than 100 nm are formed, which are nanoparticles.

Nanomodifiers are composed of modifying substances milled into nanoparticles. The required mass concentration of the nanomodifier for the effect of the modification is 0.005-0.05% (50-500 grams per 1 ton of metal to be modified) (RF Patent No. 2468110).

The indicated concentration of the nanoparticles of the modifying components in the core of the cored wire is ensured by its deformation with a decrease in diameter to a value corresponding to the following ratio:

, $$\frac{D}{d}=10-500$$

,

in the presence of a mixture of flux powder grains and grains of modifying components in the core of the flux-cored wire, having a strength 30% less than the strength of flux powder grains and with a mass content of grains of modifying components of 5-40% of flux powder grains.

When the grain strength of the modifying components is 30% less than the grain strength of the flux powder during deformation of the tubular billet with a decrease in its diameter, the modifying components are predominantly crushed to form their nanoparticles. When the strength of the grains of the modifying components is greater than the specified limit, in addition to grinding the grains of the modifying components, grains of flux powder are ground to form its nanoparticles, which leads to contamination of the nanoparticles of the modifying components with foreign particles and a decrease in the effectiveness of the nanomodifier.

в процессе деформирования трубчатой заготовки с уменьшением диаметра и при массовом содержании зерен модифицирующих компонентов 5-40% обеспечивается их измельчение и получение наночастиц модифицирующих компонентов в сердечнике порошковой проволоки 0,005% масс.At $$\frac{D}{d}=10$$

in the process of deformation of the tubular billet with a decrease in diameter and with a mass content of grains of modifying components of 5-40%, they are crushed and nanoparticles of modifying components are obtained in the core of the flux-cored wire of 0.005% by weight.

в процессе деформирования трубчатой заготовки с уменьшением диаметра и при массовом содержании зерен модифицирующих компонентов 5-40% обеспечивается их измельчение и получение наночастиц модифицирующих компонентов в сердечнике порошковой проволоки 0,05% масс.At $$\frac{D}{d}=500$$

in the process of deformation of the tubular billet with a decrease in diameter and with a mass content of grains of modifying components of 5-40%, they are crushed and nanoparticles of modifying components are obtained in the core of the flux-cored wire of 0.05% of the mass.

The mass content of grains of modifying components of less than 5% of the grains of flux powder does not allow to obtain in the process of deformation of the tubular workpiece with a decrease in the diameter of the required minimum concentration of nanoparticles of the modifying components.

When the mass content of grains of modifying components is more than 40% due to the redistribution of grinding energy supplied to the grains of the flux-cored wire core during deformation of the tubular billet with a decrease in diameter, the formation of flux nanoparticles is intensified, which leads to contamination of the modifying components nanoparticles with foreign particles and a decrease in the effectiveness of the action nanomodifier.

Sealing a tubular billet before its deformation with a decrease in diameter ensures uniformity of the density of the powder filler along the length of the cored wire.

.Example 1. Tests were carried out, in the first version of which a tubular billet of steel 20X23H18 with an outer diameter of D = 40 mm was taken. The composition of the mixture poured into the tubular billet was: flux powder with a tensile strength of 430 MPa and a powder of the modifying component — nickel with a grain fractional composition from 20 μm to 500 μm and with a main fraction of 130 μm. The tensile strength of the grains of nickel powder was 301 MPa. The grain strength of the modifying components is 30% less than the grain strength of flux powder. After filling the mixture of flux grains and nickel powder into the tubular billet, it was sealed by welding the bottoms into the ends of the tubular billet. The tubular billet was deformed at 1100 ° C by rolling in rolls to a diameter of 20 mm, and then at this temperature was deformed to reduce the outer diameter of the cored wire d = 4 mm in a rotary forging machine. During deformation, the relation $$\frac{D}{d}=10$$

.

To determine the composition and number of nickel nanoparticles formed during the preparation of the flux-cored wire, part of its core was weighed, then a colloidal solution of its particles in ethyl alcohol was obtained and filtered through a membrane with a mesh size of 100 nm. After drying the alcohol, the filtrate was weighed and the chemical composition was determined using an induction coupled plasma spectrometer. The fractional composition of the obtained nanoparticles was analyzed using an atomic force microscope.

As a result of studies, it was found that with a mass content of the modifying component (nickel) of 5% of flux grains, the mass fraction of nickel nanoparticles was 0.005%, and with a mass content of nickel of 40% e of flux grains, the mass fraction of nickel nanoparticles was 0.0054%.

When the mass content of nickel powder was 22.4% e of the flux grains, the mass fraction of nickel nanoparticles was 0.0052%.

The content of flux nanoparticles in the considered cases did not exceed 0.1% of the mass. by weight of the nanoparticles of the modifying component (nickel), which does not reduce the effectiveness of the nanomodifier (nickel nanoparticles).

The filling density of the powder filler along the length of the obtained flux-cored wires was determined by metallographic analysis (on transverse and longitudinal sections). The filling density was uniform and amounted to 68%, 68.5% and 69.5% for the content of the modifying component (nickel), respectively 5%, 22.4% and 40% of flux grains.

Example 2. Tests were carried out in accordance with the conditions set forth in example 1, but at a tensile strength of flux grains in compression of 425 MPa. The grain strength of the modifying components is 29.2% less than the grain strength of flux powder.

Tests have shown that the condition under which the grain strength limit of the modifying components is 30% less than the strength of the flux powder grains is the threshold for the onset of intensive formation of flux nanoparticles. It was found that under the conditions considered in this example, the fraction of flux nanoparticles amounted to more than 5% of the mass of the nanoparticles of the modifying component (nickel), which is an unacceptable impurity for the nanomodifier.

.Example 3. Tests were carried out in which a tubular billet of steel 08G2S with an outer diameter of D = 800 mm (hollow ingot) was taken. The ingot was sealed by welding the bottoms. The composition of the mixture filled into the tubular billet was identical to that shown in Example 1. The ingot was deformed in the hot state by the technology of producing solid wires with deformation of its outer diameter to 6.2 mm (the diameter characteristic of wire rod in the production of solid wires). Then, the tubular billet deformed to the diameter of the wire rod was dragged in the cold on the drawing mill to a diameter of 1.6 mm. The ratio of D / d was $$\frac{D}{d}=500$$

.

As a result of the tests performed, it was found that with a mass content of the modifying component (nickel) of 5% of flux grains, the mass fraction of nickel nanoparticles was 0.05%, and with a mass content of nickel of 40% e of flux grains, the mass fraction of nickel nanoparticles was 0.052%.

The filling density of the powder filler along the length of the obtained flux-cored wires, determined by metallographic analysis (on transverse and longitudinal sections), was uniform and amounted to 70% and 72% for the content of the modifying component (nickel), respectively 5% and 40% of flux grains.

.Example 4. Tests were carried out in accordance with the conditions set forth in example 3, but the deformation of the tubular billet was carried out to a diameter of 1.4 mm The ratio of D / d was $$\frac{D}{d}=571$$

.

Tests have shown that under these conditions, the proportion of the resulting nanoparticles of the modifying component (nickel) was 5% of the flux grains at a mass content of the modifying component (nickel) of 0.07%, and at a mass content of the modifying component (nickel) of 40% of the flux grains 0.08%. The resulting content of nickel nanoparticles significantly exceeds the required limit value (0.05%).

.Thus, to ensure the nanomodifying effect, the reduction in the diameter of the tubular workpiece should not exceed the ratio $$\frac{D}{d}=500$$

.

The given examples confirm the correctness of the technical solution for the selected operations, intervals in composition and design ratios.

The proposed technical solution at the selected design ratios, composition and operation intervals made it possible to improve the quality of the flux-cored wire by obtaining a uniform density of the flux-cored filler along the length of the flux-cored wire and the presence of a nanomodifier in its core in the form of nanoparticles directly formed in the process of producing flux-cored wire.

Claims (1)

A method of producing a flux-cored wire, comprising filling a mixture of flux powder grains in a tubular billet and deforming the tubular billet with a decrease in its diameter, characterized in that grains of modifying components with a mass content of 5-40 are added to the mixture consisting of flux powder grains % of the flux powder grains, and modifying components with a grain strength of 30% less than the flux powder grain strength are selected, and when the tubular workpiece is deformed, its diameter is reduced to a value corresponding to the following his relationship:
$$\frac{D}{d}=10-500$$

,
where D is the diameter of the pipe billet,
d is the outer diameter of the cored wire,
wherein the tubular preform is sealed before deformation.