Submerged-arc welding flux manufactured by utilizing electric furnace steel slag at high value and preparation method of submerged-arc welding flux

Abstract

The invention aims to provide a high-value submerged-arc welding flux manufactured by utilizing electric furnace steel slag and a preparation method thereof, and belongs to the technical field of welding materials, the submerged-arc welding flux comprises the following components in percentage by mass: powder and sodium silicate water glass accounting for 15-20% of the total mass of the powder; the powder material comprises 40 to 60 percent of electric furnace steel slag, 16.6 to 19.3 percent of fused magnesite, 12 to 18.8 percent of titanium dioxide, 1 to 16.6 percent of bauxite and 8 to 10.4 percent of fluorite or 63 percent of electric furnace steel slag, 14.9 to 17.3 percent of fused magnesite, 10.7 to 14.6 percent of titanium dioxide and 7.5 to 9 percent of fluorite. According to the method, high value-added utilization of the electric furnace steel slag can be achieved, the economic cost for manufacturing the submerged-arc welding flux is reduced by 40-60%, and the same performance as that of a commercial flux can be obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of welding materials, and in particular relates to a high-value submerged arc welding flux made from electric furnace slag and a preparation method thereof. Background Art

[0002] Electric furnace slag is solid waste discharged during the process of smelting metals in electric furnaces. Its main components are oxides such as calcium, iron, copper, silicon, magnesium, aluminum, manganese, and phosphorus. The main way to use electric furnace slag is to recycle it within the smelting company. It can be returned to the furnace as a smelting raw material, and can also be used for roadbeds, railway roadbeds, and for the production of cement raw materials and soil improvement. As a by-product of electric furnace steelmaking, electric furnace slag has a considerable output. When scrap steel is used as raw material, the amount of electric furnace slag should be 50~80kg / t, accounting for about 5%~10% (mass fraction) of the total steelmaking production.

[0003] Electric furnace slag contains a lot of substances needed for submerged arc welding flux. Therefore, for steel mills, slag may be waste, but for flux manufacturers, it is a raw material. Therefore, developing a unique technology to use waste slag to make flux can not only solve the slag disposal problem, but also protect the non-renewable resources being mined. Summary of the invention

[0004] The purpose of the present invention is to provide a submerged arc welding flux made from electric furnace steel slag with high value and a preparation method thereof, so as to realize high added value utilization of electric furnace steel slag. The present invention designs the welding flux formula by the mean difference method, obtains the maximum addition amount of electric furnace steel slag by exploring the IF function, conducts a gradient experiment on the addition amount of electric furnace steel slag, and conducts a comparative test on the welding flux formula under the maximum addition amount.

[0005] The present invention adopts the following technical solution: A high-value submerged arc welding flux made from electric furnace steel slag, comprising the following components in percentage by mass: powder and sodium silicate water glass accounting for 15-20% of the total mass of the powder; The powder includes 40-60% electric furnace slag, 16.6-19.3% fused magnesia, 12-18.8% titanium dioxide, 1-16.6% bauxite and 8-10.4% fluorite or 63% electric furnace slag, 14.9-17.3 fused magnesia, 10.7-14.6% titanium dioxide and 7.5-9% fluorite.

[0006] A method for preparing a high-value submerged arc welding flux made from electric furnace slag comprises the following steps: The first step is dry mixing: crush the electric furnace slag and sieve it, accurately weigh the remaining powder, grind it and sieve it, and mix the sieved electric furnace slag and the remaining powder evenly; The second step is wet mixing: add sodium silicate water glass binder to the dry mixed powder, mix it evenly in the mixer, and then granulate it; The third step is to sieve the formed particles after granulation in the second step to obtain uniform particles; The fourth step is to bake the uniform particles obtained in the third step at 220°C for 40 minutes; subsequently, sinter at 800°C for 90 minutes, and use a 10-50 mesh sieve to screen out particles with uniform particle size to obtain the flux.

[0007] Furthermore, the electric furnace slag in the first step is crushed and passed through a 100-mesh sieve, and the remaining powder is passed through a 180-mesh sieve.

[0008] Furthermore, the formed particles in the third step are passed through a 10-50 mesh sieve.

[0009] In the present invention, the main component of the fused magnesia powder is MgO, which is a good slag-forming agent and can play a role in adjusting the basicity of the slag. In the alkaline slag system, adding MgO can significantly increase the impact work of the weld. However, when the amount of MgO added is too much, the viscosity of the slag will be reduced, and the formation of the weld metal will be reduced.

[0010] The main component of bauxite powder is Al2O3, which can improve the arc concentration. With the increase of bauxite powder, the slag removal can be improved. However, if the addition amount is too high, pitting is prone to appear on the weld surface and the pores in the slag shell increase.

[0011] The main component of titanium dioxide is TiO2, which can improve the fluidity of slag, promote the aggregation of reduction products of weld metal, and discharge them into the slag. With the increase of TiO2, the slag removal property will be improved, making the weld metal smooth. At high temperature, it can react with CaF2 to form TiF4, which has anti-porosity effect.

[0012] The main component of fluorite is CaF2, which will generate HF at high temperature, reducing the [H] content in the steel. The generated [F] combines with [O], thereby inhibiting the transition of [O] to the deposited metal, reducing the [O] content in the deposited metal, and improving the plasticity and toughness of the weld. However, if the content is too high, the arc stabilization performance will decrease, affecting the weld formation.

[0013] The beneficial effects of the present invention are as follows: 1. The present invention adjusts the formula by the mean difference method, and can adjust the optimal formula according to different performance requirements.

[0014] 2. The present invention can realize high added value utilization of electric furnace steel slag, reduce the economic cost of manufacturing submerged arc welding flux by 40-60%, and obtain the same performance as commercial flux.

[0015] 3. The present invention reduces environmental hazards such as groundwater pollution and dust caused by the stacking of electric furnace slag by recycling solid waste electric furnace slag. DETAILED DESCRIPTION

[0016] A high-value submerged arc welding flux made from electric furnace steel slag, comprising the following components in percentage by mass: powder and sodium silicate water glass accounting for 15-20% of the total mass of the powder; The powder includes 40-60% electric furnace slag, 16.6-19.3% fused magnesia, 12-18.8% titanium dioxide, 1-16.6% bauxite and 8-10.4% fluorite or 63% electric furnace slag, 14.9-17.3 fused magnesia, 10.7-14.6% titanium dioxide and 7.5-9% fluorite.

[0017] The raw material electric furnace steel slag in the present invention is a byproduct waste of factory production, and mainly contains effective components such as manganese oxide, silicon dioxide, aluminum oxide, and iron oxide required for manufacturing submerged arc welding flux. The remaining supplementary minerals can be purchased on the market.

[0018] The present invention firstly performs XRF test on the steel slag components to determine the content of each component. i ,satisfy , select the target commercial flux by M value, and determine c in the following formula i Within the upper and lower limits of the mass fraction of each component of the target flux, determine a and b i .

[0019] The formula test ideas used in the present invention all adopt the average difference method, which is as follows: ; Among them, a: amount of electric furnace slag added; b: i : The difference between each component; c i : The amount of each component required for the target flux; x i : Substances required for submerged arc welding flux.

[0020] Assume there are m factors, and the value range of each factor is [a j , b j ], where j=1, 2,…, m.

[0021] Each factor x j The value range of [a j , b j ] is discretized into n j The value points are: ; The discretization points of all factors form an m-dimensional grid, and the number of discretization points of each factor is n j They may be different, forming an m-dimensional discrete point grid. This grid contains all possible combinations of experimental points, a total of: .

[0022] The uniform design table is a preset design matrix that contains N experimental points. The purpose is to ensure that these experimental points are evenly distributed in the design space. Given a certain uniform design table D, then each discretized point x jk Corresponds to the appropriate position x in the design table i , so that the experimental points are evenly distributed in the design space. This process is described by the following formula: ik =D ik , i=1,2,…,N; k= i=1,2,…,m.

[0023] When the final design table deviates from the actual application, a more suitable uniform design table can be constructed through optimization methods.

[0024] The method used in the present invention is proportional normalization. Assuming there are n numbers x1, x2, ...x n , the actual sum is S actual , the target sum is S target To adjust these values ​​to maintain the same proportion, so that the sum is S target Use the following formula: , : Optimized data; :x i proportion in the total; : Deviation between theoretical data and practical application.

[0025] Through the above steps, the optimized mean difference method can not only select experimental points evenly within the interval, ensure the representativeness of the experiment and reduce the number of experiments, but also better meet the needs of practical applications.

[0026] This invention mainly designs and studies the additives needed to prepare flux using electric furnace slag, with the key components being: aluminum oxide, titanium dioxide, magnesium oxide, and calcium fluoride, with the corresponding mass proportions being: x1, x2, x3, and x4. This article mainly designs the formula based on the mean difference method, and determines the value range and dosage range of each component based on theoretical analysis and preliminary tests. The remaining components in the electric furnace slag that do not require additional addition, such as manganese oxide, silicon dioxide, and calcium oxide, are taken into account, and selected for use according to the experimental accuracy. , substituted into the above formula to obtain 21 groups of formulas. The specific design scheme is shown in Table 1.

[0027] Table 1 Experimental scheme of flux formula with 40% electric furnace slag addition In order to maximize the value of electric furnace slag, the present invention uses the IF function to explore the maximum addition amount of electric furnace slag, designs a formula table with different addition amounts to conduct a gradient experiment, and repeatedly verifies three groups of formulas at the maximum addition amount.

[0028] The specific test formula is as follows: Example 1: 40% electric furnace slag, 16.6% fused magnesia, 18.8% titanium dioxide, 16.6% bauxite, and 8.0% fluorite.

[0029] Example 2: 50% electric furnace slag, 19.3% fused magnesia, 15.7% titanium dioxide, 4.6% bauxite, and 10.4% fluorite.

[0030] Example 3: 60% electric furnace slag, 17.5% fused magnesia, 12.0% titanium dioxide, 1.0% bauxite, and 9.5% fluorite.

[0031] Example 4: 63% electric furnace slag, 17.3% fused magnesia, 10.7% titanium dioxide, and 9% fluorite.

[0032] Example 5: 63% electric furnace slag, 14.9% fused magnesia, 14.6% titanium dioxide, and 7.5% fluorite.

[0033] Example 6: 63% electric furnace slag, 16.9% fused magnesia, 11.7% titanium dioxide, 8.4% fluorite.

[0034] The specific production steps are as follows: S1: dry mixing, accurately weighing the components according to the formula, grinding them through a 180-mesh sieve, and mixing them evenly with electric furnace steel slag powder that has been crushed and passed through a 100-mesh sieve; S2: wet mixing, adding 15% of the total amount of sodium silicate water glass binder after dry mixing, mixing evenly in a mixer, and then granulating; S3: Screen the formed particles in S2 to select 10-50 mesh particles.

[0035] S4: low temperature baking at 220°C for 40 min; S5: sintering at 800° C. for 90 min, using a 50-mesh sieve to remove fine particles, to obtain the flux.

[0036] Table 2 Welding process parameters Table 3 Test steel plate Table 4 Test results of weld mechanical properties The experimental results show that the prepared flux exhibits excellent mechanical properties during the welding process, which is comparable to commercial flux as a whole. Among them, the tensile strength of the welded joint of Example 4 is 464 MPa and the Vickers hardness is 314 HL, both of which are better than commercial flux; at the same time, the impact energy reaches 60 J, which is close to the performance level of commercial flux. Examples 5 and 6 use electric furnace slag with an addition amount of 63%, and the formula obtained by the optimized mean difference method shows better mechanical properties than Examples 1, 2, and 3. It can be seen that the submerged arc welding flux with 63% electric furnace slag can significantly improve the mechanical properties of the weld and obtain a more excellent welding effect.

[0037] Compared with traditional fluxes, the flux prepared by the present invention has lower production cost (reduced by about 40%) while meeting the requirements of welds, and achieves higher resource utilization efficiency and lower environmental burden by efficiently utilizing electric furnace slag.

Claims

1. A high-value submerged arc welding flux made from electric furnace slag, characterized in that: The invention comprises the following components in percentage by weight: powder and sodium silicate water glass accounting for 15-20% of the total weight of the powder; The powder includes 40-60% electric furnace slag, 16.6-19.3% fused magnesia, 12-18.8% titanium dioxide, 1-16.6% bauxite and 8-10.4% fluorite or 63% electric furnace slag, 14.9-17.3 fused magnesia, 10.7-14.6% titanium dioxide and 7.5-9% fluorite.

2. A method for preparing a high-value submerged arc welding flux made from electric furnace slag as claimed in claim 1, characterized in that: The steps include: The first step is dry mixing: crush the electric furnace slag and sieve it, accurately weigh the remaining powder, grind it and sieve it, and mix the sieved electric furnace slag and the remaining powder evenly; The second step is wet mixing: add sodium silicate water glass binder to the dry mixed powder, mix it evenly in the mixer, and then granulate it; The third step is to sieve the formed particles after granulation in the second step to obtain uniform particles; The fourth step is to bake the uniform particles obtained in the third step at 220°C for 40 minutes; subsequently, sinter at 800°C for 90 minutes, and use a 10-50 mesh sieve to screen out particles with uniform particle size to obtain the flux.

3. The method for preparing a high-value submerged arc welding flux made from electric furnace slag according to claim 2, characterized in that: The electric furnace slag in the first step is crushed and passed through a 100-mesh sieve, and the remaining powder is passed through a 180-mesh sieve.

4. The method for preparing a high-value submerged arc welding flux made from electric furnace slag according to claim 2, characterized in that: In the third step, the formed particles are passed through a 10-50 mesh screen.

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