Iron-aluminum intermediate alloy and preparation method thereof

Abstract

The invention discloses an iron-aluminum intermediate alloy and a preparation method thereof. The iron-aluminum intermediate alloy comprises the following components in percentage by weight: 39-40% of Al; 58 to 64 percent of Fe; 0.30% or less of Si; o: < = 0.15; n: less than or equal to 0.04; and C: less than or equal to 0.10. According to the method, the iron and the aluminum are prepared into the iron-aluminum intermediate alloy, so that the Fe element can be more uniformly added into the smelting of the titanium alloy, and the problem that the Fe element is easy to segregate during the smelting of the titanium alloy is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of master alloy preparation, and in particular relates to an iron-aluminum master alloy and a preparation method thereof. Background Art

[0002] Titanium is an important structural metal developed in the 1950s. Titanium alloys have high strength, good corrosion resistance and high heat resistance. In the 1950s and 1960s, the main focus was on the development of high-temperature titanium alloys for aircraft engines and structural titanium alloys for fuselages. In the 1970s, a number of corrosion-resistant titanium alloys were developed. Since the 1980s, corrosion-resistant titanium alloys and high-strength titanium alloys have been further developed. Titanium alloys are mainly used to make aircraft engine compressor components, followed by rockets, missiles and high-speed aircraft structural parts. Adding a master alloy with uniform composition is the key to improving the metallurgical quality of titanium alloys, and this method has been widely used in the industrial production of titanium alloys. Aluminum is the most commonly used α-stabilizing element in industry. By substitution solid solution strengthening, adding an appropriate amount of aluminum can improve the room temperature and high temperature strength and thermal strength of titanium alloys. Therefore, almost all types of titanium alloys at home and abroad have added an appropriate amount of aluminum. Iron is one of the strongest β-stabilizing elements and a slow eutectoid alloying element, but its thermal stability is poor. It exists as the main element in TA23, TA36, TB3, TB4, TB6, TC6, TC10, TC15, TC18, TC24, TC27, TC28 and TC29 titanium alloys, undergoing eutectoid phase transformation with titanium to form compounds, lowering the phase transition point, playing a role in solid solution strengthening, and improving room temperature tensile strength. In other titanium alloys, Fe is an impurity element. In order to improve the tensile strength, trace amounts of Fe are also added during the production of some titanium alloy ingots such as TA5, TA7, and TC4. In the early stage, the Fe element was added to titanium alloy production mainly in the form of special alloys or pure metal additives such as vanadium aluminum iron, aluminum molybdenum chromium iron silicon, and iron nails. If iron is added as a single substance during titanium alloy smelting, segregation is likely to occur during smelting, and the subsequent processed rods also have relatively more β-spot problems due to local segregation of components; and when smelting some titanium alloys that only need to add iron elements, the above-mentioned intermediate alloy cannot meet the requirements, resulting in the addition of unnecessary elements, which can only be introduced using iron nails; therefore, in order to allow the Fe element to be evenly added to the smelting of titanium alloys without bringing in other unnecessary elements, it is necessary to provide a new intermediate alloy to solve the technical problem of large-size ingot production. Summary of the invention

[0003] In order to solve the above problems existing in the prior art, the present invention provides an iron-aluminum master alloy and a preparation method thereof. The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0004] An iron-aluminum master alloy comprises the following components in weight percentage: Al: 47-50%; Fe: 48-52%; Si: ≤0.30; O: ≤0.15; N: ≤0.04; and C: ≤0.10.

[0005] Another embodiment of the present invention discloses a method for preparing an iron-aluminum master alloy, comprising: step 1: charging pure aluminum and low-carbon steel into a crucible in a ratio of 1:1.5-1.6, and placing the crucible in a medium-frequency induction furnace;

[0006] Step 2: Evacuate the furnace. When the vacuum reaches 4-2 Pa, start power heating and increase the power of the medium frequency induction furnace to 25-35 KW. Then increase the power of the medium frequency induction furnace by 18-22 KW every 4-6 minutes until all the materials in the crucible are melted and the liquid level is stable. Continue refining for 8-10 minutes and control the liquid level temperature to 1400-1450°C. Then gradually reduce the power of the medium frequency induction furnace to 20 KW to allow the materials in the crucible to start cooling.

[0007] Step 3: When the temperature of the flow in the crucible drops to 1250-1300° C., the power is turned off, and then an iron-aluminum master alloy ingot is cast;

[0008] Step 4: finishing and crushing the iron-aluminum master alloy ingot to obtain the iron-aluminum master alloy.

[0009] Furthermore, the pure aluminum is any one of Al99.70, Al99.85, and Al99.99.

[0010] Furthermore, the low carbon steel is any one of Q195, Q235 and Q215.

[0011] Furthermore, the crucible is an alumina crucible, the alumina crucible is separated from the coil outside the crucible by filling with a heat-insulating material, and the gap after the heat-insulating material is filled is filled with capacitor magnesia mixed with water glass.

[0012] Furthermore, the weight ratio of the water glass to the capacitor magnesia is 1:15-25.

[0013] Furthermore, in step 1, when pure aluminum and low-carbon steel are loaded into the crucible, the pure aluminum is first placed at the bottom of the crucible, and then the low-carbon steel is placed above the pure aluminum.

[0014] Beneficial effects of the present invention:

[0015] 1. The present invention prepares an iron-aluminum master alloy from iron and aluminum, so that the Fe element can be more evenly added to the smelting of the titanium alloy, thereby solving the problem that the Fe element is prone to segregation during the smelting of the titanium alloy;

[0016] 2. The iron-aluminum master alloy is made in one step by medium-frequency induction melting, and the alloy composition is more uniform and the content of impurity elements is lower, thereby ultimately improving the performance of the titanium alloy;

[0017] 3. Since the graphite crucible is frequently changed between high-frequency vacuum and atmospheric atmosphere, resulting in serious oxidation and burning, in order to extend the service life of the crucible and avoid the crucible slag affecting product quality, the present invention adopts an alumina crucible and uses asbestos capacitor magnesia sand for filling and isolation, thereby successfully solving the insulation, magnetic conductivity and heat preservation problems of the alumina crucible.

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The composition analysis report of the iron-aluminum master alloy prepared in Example 1;

[0020] Figure 2 This is the composition analysis report of the iron-aluminum master alloy prepared in Example 2. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments, but the embodiments of the present invention are not limited thereto.

[0022] Example 1

[0023] The embodiment of the present invention provides an iron-aluminum master alloy, which includes the following components by weight percentage: Al: 39-40%; Fe: 58-64%; Si: ≤0.30; O: ≤0.15; N: ≤0.04; C: ≤0.10. The iron-aluminum master alloy is made of iron and aluminum to form a master alloy, so that the Fe element can be more evenly added to the smelting of the titanium alloy, solving the problem that the Fe element is easy to segregate during the smelting of the titanium alloy.

[0024] Example 2

[0025] The embodiment of the present invention provides a method for preparing an iron-aluminum master alloy, which specifically comprises the following steps:

[0026] Step 1: The raw materials are Al99.70 aluminum blocks and Q195 low-carbon steel, and the chemical composition tables are shown in Table 1 and Table 2. When these two raw materials are smelted, a slag layer will be formed on the surface of the ingot, and the impurities in the ingot will be removed along with the slag layer, thereby improving the quality of the ingot.

[0027] The aluminum block is sheared and polished. The weight of a single aluminum block does not exceed 2kg. The surface of the polished aluminum block is clean and free of oil and dirt, and there is no oxidation visually. 12kg of the polished aluminum block and 18.0kg of low-carbon steel are taken and then loaded into an alumina crucible. When loading, the aluminum block is first loaded into the bottom of the crucible, and then the low-carbon steel is placed on top of the aluminum block. Finally, the crucible is placed in a medium-frequency induction furnace.

[0028] Table 1 Chemical composition of Al99.70

[0029]

[0030] Table 2 Chemical composition of Q195

[0031]

[0032] Since the graphite crucible is frequently changed between high-frequency vacuum and atmospheric atmosphere, it is seriously oxidized and burned. In order to extend the service life of the crucible and prevent the crucible from falling off and affecting the product quality, an alumina crucible is selected as the melting crucible. The alumina crucible is separated from the outer coil of the crucible by asbestos, and the gap after filling with asbestos is filled and smoothed with capacitor magnesia mixed with water glass, so as to achieve insulation, magnetic conductivity and heat preservation for the crucible. The weight ratio of water glass to capacitor magnesia is 1:15.

[0033] During the smelting process, the burning loss of the aluminum block and the low-carbon steel at different temperatures must be considered first, and the loading order of the materials must be arranged in a certain order. In the present invention, the aluminum block is placed at the bottom of the crucible, and the low-carbon steel is placed above the aluminum block, so that the burning loss of the two raw materials during the smelting process is minimized. In addition, the aluminum block has a low melting point, and a molten pool can be formed first, so that the low-carbon steel can be melted faster, saving production time and production costs.

[0034] Step 2: Evacuate the medium frequency induction furnace until the vacuum degree in the furnace is 4Pa, start power heating, and increase the power of the medium frequency induction furnace to 30KW. Then increase the power of the medium frequency induction furnace by 20KW every 4 minutes until all the materials in the crucible are melted and the liquid level is stable. Continue refining for 8 minutes, and control the liquid level temperature to 1400-1450℃. Then gradually reduce the power of the medium frequency induction furnace to 20KW, so that the materials in the crucible begin to cool.

[0035] Step 3: When the temperature of the material in the crucible drops to 1250-1300°C, turn off the power, and then cast to obtain an iron-aluminum master alloy ingot. This casting temperature can basically cast the material in the molten pool, but will not damage the mold due to excessive temperature, thereby destroying the composition uniformity of the ingot.

[0036] Step 4: Finish and crush the iron-aluminum master alloy ingot to obtain an iron-aluminum master alloy. The chemical composition analysis report of the iron-aluminum master alloy is as follows: Figure 1 As shown in the figure, it can be seen that the content of impurity elements in the obtained iron-aluminum intermediate alloy is low.

[0037] Example 3

[0038] The embodiment of the present invention provides a method for preparing an iron-aluminum master alloy, which specifically comprises the following steps:

[0039] Step 1: The raw materials are Al99.85 aluminum blocks and Q215 low-carbon steel, and the chemical composition tables are shown in Table 3 and Table 4. When these two raw materials are smelted, a slag layer will be formed on the surface of the ingot, and the impurities in the ingot will be removed along with the slag layer, thereby improving the quality of the ingot.

[0040] The aluminum block is sheared and polished. The weight of a single aluminum block does not exceed 2kg. The surface of the polished aluminum block is clean and free of oil and dirt, and there is no oxidation visible on the surface. 11.6kg of polished aluminum block and 18.4kg of low-carbon steel are taken and then loaded into an alumina crucible. When loading, the aluminum block is first loaded into the bottom of the crucible, and then the low-carbon steel is placed on top of the aluminum block. Finally, the crucible is placed into the medium-frequency induction furnace.

[0041] Table 3 Chemical composition of Al99.85

[0042]

[0043] Table 4 Chemical composition of Q215

[0044]

[0045] Since the graphite crucible is frequently changed between high-frequency vacuum and atmospheric atmosphere, it is seriously oxidized and burned. In order to extend the service life of the crucible and prevent the crucible from falling off and affecting the product quality, an alumina crucible is selected as the melting crucible. The alumina crucible is separated from the coil outside the crucible by asbestos, and the gap after filling with asbestos is filled and smoothed with capacitor magnesia mixed with water glass, so as to achieve insulation, magnetic conductivity and heat preservation for the crucible. The weight ratio of water glass to capacitor magnesia is 1:20.

[0046] During the smelting process, the burning loss of the aluminum block and the low-carbon steel at different temperatures must be considered first, and the loading order of the materials must be arranged in a certain order. In the present invention, the aluminum block is placed at the bottom of the crucible, and the low-carbon steel is placed above the aluminum block, so that the burning loss of the two raw materials during the smelting process is minimized. In addition, the aluminum block has a low melting point, and a molten pool can be formed first, so that the low-carbon steel can be melted faster, saving production time and production costs.

[0047] Step 2: Evacuate the medium frequency induction furnace until the vacuum degree in the furnace is 2Pa, start power heating, and increase the power of the medium frequency induction furnace to 35KW. Then increase the power of the medium frequency induction furnace by 18KW every 6 minutes until all the materials in the crucible are melted and the liquid level is stable. Continue refining for 10 minutes, and control the liquid level temperature to 1400-1450℃. Then gradually reduce the power of the medium frequency induction furnace to 20KW, so that the materials in the crucible begin to cool.

[0048] Step 3: When the temperature of the material in the crucible drops to 1250-1300°C, turn off the power, and then cast to obtain an iron-aluminum master alloy ingot. This casting temperature can basically cast the material in the molten pool, but will not damage the mold due to excessive temperature, thereby destroying the composition uniformity of the ingot.

[0049] Step 4: Finish and crush the iron-aluminum master alloy ingot to obtain an iron-aluminum master alloy. The chemical composition analysis report of the iron-aluminum master alloy is as follows: Figure 2 As shown in the figure, it can be seen that the content of impurity elements in the obtained iron-aluminum intermediate alloy is low.

[0050] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. An iron-aluminum master alloy, It is characterized in that It includes the following components in weight percentage: Al: 39-40%; Fe: 58-64%; Si: ≤0.30; O: ≤0.15; N：≤0.04； C：≤0.10。 2. A method for preparing an iron-aluminum master alloy as claimed in claim 1, It is characterized in that include: Step 1: put pure aluminum and low carbon steel into a crucible in a ratio of 1:1.5-1.6 and place it in a medium frequency induction furnace; Step 2: Evacuate the furnace. When the vacuum reaches 4~2Pa, start heating with electricity and increase the power of the medium frequency induction furnace to 25~35KW. Then increase the power of the medium frequency induction furnace by 18~22KW every 4~6 minutes until all the materials in the crucible are melted and the liquid level is stable. Continue refining for 8~10 minutes and control the liquid level temperature to 1400~1450℃. Then gradually reduce the power of the medium frequency induction furnace to 20KW to allow the materials in the crucible to start cooling. Step 3: When the temperature of the material in the crucible drops to 1250-1300°C, turn off the power, and then cast to obtain an iron-aluminum master alloy ingot; Step 4: finishing and crushing the iron-aluminum master alloy ingot to obtain the iron-aluminum master alloy.

3. The method for preparing the iron-aluminum master alloy according to claim 1, It is characterized in that The pure aluminum is any one of Al99.70, Al99.85, and Al99.

99.

4. The method for preparing the iron-aluminum master alloy according to claim 1, It is characterized in that The low carbon steel is any one of Q195, Q235 and Q215.

5. The method for preparing the iron-aluminum master alloy according to claim 1, It is characterized in that The crucible is an alumina crucible, and the alumina crucible is separated from the coil outside the crucible by filling with a heat-insulating material, and the gap after the heat-insulating material is filled is filled with capacitor magnesia mixed with water glass.

6. The method for preparing the iron-aluminum master alloy according to claim 5, It is characterized in that The weight ratio of the water glass to the capacitor magnesia is 1:15-25.

7. The method for preparing the iron-aluminum master alloy according to claim 1, It is characterized in that In the step 1, when pure aluminum and low-carbon steel are loaded into the crucible, the pure aluminum is first placed at the bottom of the crucible, and then the low-carbon steel is placed above the pure aluminum.

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