Preparation method of high-manganese steel composite modifier cored wire

Abstract

The invention discloses a preparation method of a high manganese steel composite alterant cored wire, and relates to the technical field of alterants, the high manganese steel composite alterant cored wire is composed of 16-18 parts of ferrotitanium, 11-13 parts of ferroboron, 31-35 parts of rare earth silicon and 24-28 parts of scrap steel, and the preparation method comprises the steps of smelting, casting, smashing, mixing, inspecting and rolling. According to the preparation method of the high-manganese steel composite modifier cored wire, size refinement of inclusions can be promoted, conditions are created for epitaxial growth of TiN particles, the high-temperature delta phase of the formed composite inclusions is refined, and growth of austenite grains is indirectly inhibited; wherein magnesium modifies a deoxidized and desulfurized product into a new phase with good wettability with molten steel, Ti and B generate a TiB2 intermediate alloy as an external core, the nucleation condition during solidification of the molten high-manganese steel is changed, the solidification structure of the high-manganese steel is refined, the strength and toughness of the high-manganese steel are improved, and the service life of the high-manganese steel is prolonged. The multifunctional composite effects of deoxidation, desulfurization, degassing, heterogeneous nucleation grain refinement, microalloying, inclusion form improvement and the like are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of modifiers, and more particularly to a method for preparing a high manganese steel composite modifier cored wire. Background Art

[0002] High-performance high-manganese steel austenite matrix casting products are the basis and core components of high-end crushers, mills and other equipment, such as high-manganese steel hammers, jaw plates, liners, etc. They are mainly used for wear-resistant parts of crushers, ball mills and other equipment. Especially under the action of large impact or contact stress, the surface layer can quickly produce work hardening, with high strength, high wear resistance and good toughness.

[0003] In the process of high manganese steel casting, there are problems such as inclusions, segregation, coarse grains and cracks, which seriously restrict its production and application. High manganese steel composite modifier cored wire is a material used to improve the casting performance of high manganese steel. It improves the microstructure and macroscopic properties of high manganese steel by adding a specific composite modifier during the smelting process. This cored wire is usually composed of a metal sheath wrapped with powders containing multiple alloy elements and / or rare earth elements. These elements can play a variety of roles in molten metal. However, the current high manganese steel composite modifier cored wire still has the following problems:

[0004] 1. The molten steel contains oxygen and sulfur, which will form a large number of oxide (Al2O3) and sulfide (MnS) inclusions. These inclusions will not only reduce the purity of the material, but also become the source of cracks, seriously affecting the mechanical properties of the material, especially fatigue life and corrosion resistance.

[0005] 2. It has a high content of hydrogen and nitrogen. Hydrogen and nitrogen will cause pores in the molten steel. These pores will form voids during the solidification process, reducing the density and mechanical properties of the material. Although the modifier cored wire has the function of degassing, the degassing is not thorough. The residual gas will form bubbles during the cooling process, affecting the surface quality and internal structure of the material, resulting in a decrease in material performance.

[0006] 3. The grains of high manganese steel will coarsen during the solidification process. Coarse grains will cause the strength and toughness of the material to decrease, and will accelerate the aging and failure of the material. At the same time, coarse grains will make the grain boundaries fragile and easy to break when subjected to stress, reducing the overall performance of the material.

[0007] Therefore, it is necessary to propose a method for preparing high manganese steel composite modifier cored wire to solve the above problems. Summary of the invention

[0008] The purpose of the present invention is to solve the problems raised in the above background technology, and provide a method for preparing a high manganese steel composite modifier cored wire.

[0009] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0010] A method for preparing a high manganese steel composite modifier cored wire, comprising 16-18 parts of ferrotitanium, 11-13 parts of ferroboron, 31-35 parts of rare earth silicon, and 24-28 parts of scrap steel;

[0011] The method for preparing high manganese steel composite modifier cored wire comprises the following steps:

[0012] S1. Melting: melting the titanium iron, boron iron and scrap steel in a medium frequency furnace, adding rare earth silicon, adding a covering agent to the furnace during melting, and introducing nitrogen into the medium frequency furnace as a protective gas. The melting temperature is 1320-1360°C, the melting time is 0.4-0.5 hours, and the alloy melt is obtained after melting.

[0013] S2, casting: pouring the alloy melt into a metal ingot mold to obtain an alloy ingot;

[0014] S3, crushing: crush the alloy ingot into 4mm-8mm alloy blocks using a pneumatic hammer, and then crush the alloy blocks using a granulator. After crushing, pass through a 6-8 mesh sieve to obtain alloy powder;

[0015] S4, mixing: the alloy powder is divided into two parts, the first part of the alloy powder and magnesium particles are placed in a three-dimensional mixer for uniform mixing, and the cored wire mixture is obtained after the mixing time is 0.2-0.5 hours, and the second part of the alloy powder is reserved;

[0016] S5. Inspection: Test the cored wire mixture and the second batch of alloy powder, and keep them for later use after they pass the test;

[0017] S6. Coiling: Use Q195 cold-rolled steel strip to weigh the first mixed material and the second alloy powder separately on the cored wire machine, feed them into the cored wire machine for coating by alternating feeding of equal amounts, then use a winding machine to roll the cored wire into a coil, finally inspect and package the coil to obtain the finished cored wire.

[0018] Preferably, the amount of covering agent added in the S1 smelting step is 0.5%-1.0% of the total mass of the raw materials, and the composition of the covering agent is 50-60% potassium fluoride and 40-50% graphite powder.

[0019] Preferably, during the S2 casting step, the distance between the medium frequency furnace mouth and the ingot mold is 100-400 mm.

[0020] Preferably, the crushing and screening in the S3 comminution step are carried out in a nitrogen protection environment.

[0021] Preferably, the particle size of the magnesium particles in the S4 mixing step is in the range of 0.1-1.2 mm, and the particle size of the alloy powder is less than 2.5 mm.

[0022] Preferably, in the S6 rolling step, when the steel strip wraps the core wire mixture, the interface of the steel strip is mechanically bitten.

[0023] Preferably, the alloy powder obtained in the S3 pulverizing step has a composition of titanium: 4.5%-6.8%, boron: 2.3%-3.4%, cerium: 9.1%-11.3%, silicon: 19.3%-23.8%, and the remainder is iron and unavoidable impurities.

[0024] Preferably, the distance of alternating filling and feeding during the S6 rolling step is 5 mm.

[0025] Preferably, the amount of magnesium particles added in the S4 mixing step is 10.0%-12.0% of the total mass of the alloy powder.

[0026] Preferably, the core wire mixture of the cored wire in the S6 rolling step is composed of: magnesium: 10.0%-12.0%, titanium: 4.0-6.0%, boron: 2.0-3.0%, cerium: 8.0-10.0%, silicon: 17.0%-21.0%, and the remainder is iron and unavoidable impurities.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] Through the mixing of Mg, Ti, Ce, and B, metal modified inclusions can be generated, which promote the refinement of inclusion size and create conditions for the epitaxial growth of TiN particles. The formed composite inclusions refine the high-temperature δ phase and indirectly inhibit the growth of austenite grains. Among them, magnesium transforms the deoxidation and desulfurization products into new phases (MgO, MgAl2O4, etc.) with good wettability with molten steel, inhibits the aggregation and growth of inclusion particles, keeps them in submicron size, and disperses them in the steel, providing particles for the non-spontaneous nucleation of steel. At the same time, it has a stirring effect on the molten steel, which is beneficial to the floating and degassing of inclusions, purifying the molten steel and refining the grains; Ti and B generate TiB2 intermediate alloy as a foreign core, which changes the nucleation conditions of the high manganese steel liquid during solidification, refines the solidification structure of the high manganese steel, and improves the strength and toughness of the high manganese steel. At the same time, it reduces the AlN brittle and hard phase that is easily stored in the grain boundary produced by Al deoxidation, achieving deoxidation, desulfurization, degassing, heterogeneous nucleation to refine grains, microalloying, and improvement of inclusion morphology. Multifunctional composite effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a metallographic structure diagram of the present invention without adding a high manganese steel composite modifier;

[0030] Figure 2The metallographic structure diagram of the composite modifier added to high manganese steel of the present invention;

[0031] Figure 3 A line graph of the test number and hardness of the present invention;

[0032] Figure 4 A line graph showing the test number and impact absorption energy of the present invention;

[0033] Figure 5 A line graph of the test number and tensile strength of the present invention;

[0034] Figure 6 A line graph of the test number and yield strength of the present invention;

[0035] Figure 7 A line graph showing the test number and elongation of the present invention;

[0036] Figure 8 It is a line graph of the test number and the cross-sectional shrinkage rate of the present invention. DETAILED DESCRIPTION

[0037] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Example:

[0039] It is composed of 18 parts of ferrotitanium, 13 parts of ferroboron, 34 parts of rare earth silicon, and 28 parts of scrap steel;

[0040] The method for preparing high manganese steel composite modifier cored wire comprises the following steps:

[0041] S1. Melting: Place the above-mentioned ferrotitanium, ferroboron and scrap steel in a medium frequency furnace for melting, then add rare earth silicon, add 0.5%-1.0% of the total mass of the raw materials into the furnace during smelting, the covering agent is composed of 55% potassium fluoride and 45% graphite powder, and nitrogen is introduced into the medium frequency furnace as a protective gas, the melting temperature is 1360°C, the melting time is 0.5 hour, and the alloy melt is obtained after melting;

[0042] S2, casting: pouring the alloy melt into a metal ingot mold to obtain an alloy ingot, the distance between the furnace mouth and the ingot mold is 200 mm;

[0043] S3, crushing: crush the alloy ingot into 6 mm alloy blocks using a pneumatic hammer, and then crush the alloy blocks using a granulator. After crushing, pass through a 6-mesh sieve to obtain alloy powder;

[0044] S4, mixing: the alloy powder is divided into two parts, the first part of the alloy powder and magnesium particles are placed in a three-dimensional mixer for uniform mixing, and the cored wire mixture is obtained after the mixing time is 0.5 hours, and the second part of the alloy powder is reserved, and the amount of magnesium particles added is 11.77% of the total mass of the alloy powder;

[0045] S5. Inspection: Test the cored wire mixture and the second batch of alloy powder, and keep them for later use after they pass the test;

[0046] S6. Coiling: Use Q195 cold-rolled steel strip to weigh the first mixed material and the second alloy powder separately on the cored wire machine, feed them into the cored wire machine for coating by alternating feeding of equal amounts, then use a winding machine to roll the cored wire into a coil, finally inspect and package the coil to obtain the finished cored wire.

[0047] The following is a comparison between the high manganese steel castings to which the high manganese steel composite modifier is added and the examples without the addition.

[0048] 1. The following is a comparison of the chemical composition of high manganese steel castings with designed addition amount and actual addition amount:

[0049] Table 1, Chemical composition of high manganese steel castings (wt.%)

[0050]

[0051] 2. The following is a comparison of the metallographic structure of the test block before and after adding the high manganese steel composite modifier

[0052] Figure 1 Before application, the grain size is 00 and the inclusions are 3A;

[0053] Figure 2 After application, the grain size is 2.5 and the inclusions are 2A;

[0054] Depend on Figure 1 and Figure 2 It can be seen that Figure 1 The grains of the sample without modifier are coarse. Figure 2 After adding the modifier: the grains are obviously refined: the grain size increases by 2.5 levels; the shape of the inclusions is changed, and the cast carbide increases by 1 level.

[0055] 3. The hardness and impact absorption energy of high manganese steel castings with different addition amounts are compared below. Three samples are taken for each test:

[0056] Table 2, Hardness and impact test results

[0057]

[0058]

[0059] Figure 3 is a line graph of test number and hardness;

[0060] Figure 4 It is a line graph of test number and impact absorbed energy;

[0061] From Table 2, Figure 3 and Figure 4 It can be seen that the hardness does not change much after adding the modifier, while the impact absorption energy increases by 8-16%, with the No. 3 and No. 4 samples increasing the most, reaching more than 16%. The toughness is greatly improved due to grain refinement. The impact absorption energy of the casting body samples exceeds the national standard requirements. Although the impact absorption energy of No. 6 is also improved, the hardness will be greatly reduced and cannot meet the use requirements.

[0062] 4. The following tensile tests were conducted on high manganese steel castings with different addition amounts, with 3 specimens taken for each test:

[0063] Table 3, tensile test record

[0064]

[0065] Figure 5 is a line graph of test number and tensile strength;

[0066] Figure 6 is a line graph of test number and yield strength;

[0067] Figure 7 is a line graph of test number and elongation;

[0068] Figure 8 It is a line graph of test number and area reduction;

[0069] Table 3 Figures 5 to 8 The tensile test results are shown in Figure 2. Three samples were taken for each test. It can be seen that the yield strength, tensile strength, elongation after fracture and cross-sectional shrinkage of the samples with the addition of the modifier are all improved to a certain extent compared with the original samples. Among them, the above indicators of sample No. 3 increased by 54.7%, 22.5%, 82.8% and 51.4% respectively, indicating that the added high manganese steel composite modifier can refine the grains, thereby improving the strength, hardness and plasticity and toughness indicators of the samples.

[0070] 5. Summary

[0071] The above data show that the high manganese steel composite modifier prepared by the high manganese steel composite modifier preparation method of the present application can play a role in refining the grains, thereby improving the product performance of the finished high manganese steel. Among them, the performance is best when 15% is added. At the same time, the grains can be significantly refined and the grain size can be increased by 2.5 levels.

Claims

1. A method for preparing a high manganese steel composite modifier cored wire, characterized in that: It is composed of 16-18 parts of ferrotitanium, 11-13 parts of ferroboron, 31-35 parts of rare earth silicon, and 24-28 parts of scrap steel; The method for preparing high manganese steel composite modifier cored wire comprises the following steps: S1. Melting: melting the titanium iron, boron iron and scrap steel in a medium frequency furnace, adding rare earth silicon, adding a covering agent to the furnace during melting, and introducing nitrogen into the medium frequency furnace as a protective gas. The melting temperature is 1320-1360°C, the melting time is 0.4-0.5 hours, and the alloy melt is obtained after melting. S2, casting: pouring the alloy melt into a metal ingot mold to obtain an alloy ingot; S3, crushing: crush the alloy ingot into 4mm-8mm alloy blocks using a pneumatic hammer, and then crush the alloy blocks using a granulator. After crushing, pass through a 6-8 mesh sieve to obtain alloy powder; S4, mixing: the alloy powder is divided into two parts, the first part of the alloy powder and magnesium particles are placed in a three-dimensional mixer for uniform mixing, and the cored wire mixture is obtained after the mixing time is 0.2-0.5 hours, and the second part of the alloy powder is reserved; S5. Inspection: Test the cored wire mixture and the second batch of alloy powder, and keep them for later use after they pass the test; S6. Coiling: Use Q195 cold-rolled steel strip to weigh the first mixed material and the second alloy powder separately on the cored wire machine, feed them into the cored wire machine for coating by alternating feeding of equal amounts, then use a winding machine to roll the cored wire into a coil, finally inspect and package the coil to obtain the finished cored wire.

2. The method for preparing a high manganese steel composite modifier cored wire according to claim 1, characterized in that: The amount of covering agent added in the S1 smelting step is 0.5%-1.0% of the total mass of the raw materials, and the composition of the covering agent is 50-60% potassium fluoride and 40-50% graphite powder.

3. The method for preparing a high manganese steel composite modifier cored wire according to claim 2, characterized in that: During the S2 casting step, the distance between the medium frequency furnace mouth and the ingot mold is 100-400 mm.

4. The method for preparing a high manganese steel composite modifier cored wire according to claim 3, characterized in that: The crushing and screening in the S3 pulverizing step are carried out in a nitrogen protection environment.

5. The method for preparing a high manganese steel composite modifier cored wire according to claim 4, characterized in that: The particle size of the magnesium particles in the S4 mixing step ranges from 0.1 to 1.2 mm, and the particle size of the alloy powder is less than 2.5 mm.

6. The method for preparing a high manganese steel composite modifier cored wire according to claim 5, characterized in that: In the S6 rolling step, when the steel strip wraps the core wire mixture, the interface of the steel strip is mechanically bitten.

7. The method for preparing a high manganese steel composite modifier cored wire according to claim 6, characterized in that: The alloy powder obtained in the S3 pulverizing step has the following components: titanium: 4.5%-6.8%, boron: 2.3%-3.4%, cerium: 9.1%-11.3%, silicon: 19.3%-23.8%, and the remainder is iron and unavoidable impurities.

8. The method for preparing a high manganese steel composite modifier cored wire according to claim 7, characterized in that: The distance of alternating filling and feeding during the S6 rolling step is 5 mm.

9. The method for preparing a high manganese steel composite modifier cored wire according to claim 1, characterized in that: The amount of magnesium particles added in the S4 mixing step is 10.0%-12.0% of the total mass of the alloy powder.

10. The method for preparing a high manganese steel composite modifier cored wire according to claim 1, characterized in that: The composition of the core wire mixture of the cored wire in the S6 winding step is: magnesium: 10.0%-12.0%, titanium: 4.0-6.0%, boron: 2.0-3.0%, cerium: 8.0-10.0%, silicon: 17.0%-21.0%, and the balance is iron and unavoidable impurities.

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