Bismuth-titanium-manganese-selenium alloy for environment-friendly bismuth-containing free-cutting steel and preparation method thereof
阅读说明：本技术 一种环保型含铋易切削钢用铋钛锰硒合金及其制备方法 (Bismuth-titanium-manganese-selenium alloy for environment-friendly bismuth-containing free-cutting steel and preparation method thereof ) 是由 万勇 凌霄 马冬 高山 温永红 李�杰 程子豪 于 2021-07-15 设计创作，主要内容包括：本发明公开了一种环保型含铋易切削钢用铋钛锰硒合金及其制备方法,属于合金生产技术领域。本发明以高纯铋块、硒粒、低碳锰块和海绵钛为原料,通过采用感应炉分阶段升温工艺和精确控制各原料的比例、加入顺序及造渣剂成分得到铋钛锰硒高温熔体,随后再进行雾化、冷凝处理,最终得到具有一定粒度的铋钛锰硒合金颗粒,其成分按重量百分比为：Bi：40％～50％,Ti：5％～10％,Se：5％～10％,Mn：35～45％,C：0％～0.1％且5≤Bi/Ti≤8。本发明的铋钛锰硒合金在高温熔炼过程不易氧化和气化,烧损少,烟气污染小,该合金用于高温下的环保型含铋易切削钢合金化处理时气化少,合金收得率高。(The invention discloses an environment-friendly bismuth-titanium-manganese-selenium alloy for bismuth-containing free-cutting steel and a preparation method thereof, belonging to the technical field of alloy production. The invention takes high-purity bismuth blocks, selenium particles, low-carbon manganese blocks and sponge titanium as raw materials, obtains bismuth titanium manganese selenium high-temperature melt by adopting a staged heating process of an induction furnace and accurately controlling the proportion, the adding sequence and the components of a slag former, and then carries out atomization and condensation treatment to finally obtain bismuth titanium manganese selenium alloy particles with certain granularity, wherein the components are as follows by weight percent: bi: 40-50%, Ti: 5% -10%, Se: 5% -10%, Mn: 35-45%, C: 0 to 0.1 percent and more than or equal to 5 and less than or equal to 8 percent of Bi/Ti. The bismuth titanium manganese selenium alloy is not easy to oxidize and gasify in the high-temperature smelting process, has less burning loss and less smoke pollution, and has less gasification and high alloy yield when being used for the alloying treatment of environment-friendly bismuth-containing free-cutting steel at high temperature.)
1. The bismuth titanium manganese selenium alloy for the environment-friendly bismuth-containing free-cutting steel is characterized by comprising, by weight, 40% -50%, 5% -10%, 35-45%, 5% -10% and 0% -0.1% of Bi/Ti which is not less than 5 and not more than 8% of Bi, Ti, Mn, Se and C and inevitable impurities.
2. The method for preparing the bismuth titanium manganese selenium alloy for the environment-friendly bismuth-containing free-cutting steel as claimed in claim 1, wherein the method comprises the following steps:
step one, melting and heating high-purity bismuth blocks and selenium particles through induction melting, adding a first batch of low-carbon manganese blocks into a melt when the temperature of the melt is raised to 600-650 ℃, and then adding NaCl and CaCl into the surface layer of the low-carbon manganese blocks2Covering and slagging are carried out;
step two, when the temperature of the melt rises to 955-980 ℃, poking a slag layer, adding a second batch of low-carbon manganese blocks into the melt, and then adding a first batch of CaO into the slag;
step three, when the temperature of the melt rises to 1030-1100 ℃, poking a slag layer, adding a third batch of low-carbon manganese blocks and titanium sponge into the melt, and then adding a second batch of CaO into the slag;
fourthly, after the temperature of the melt is increased to 1165-1205 ℃, removing slag on the surface layer of the melt, then injecting the alloy melt into a high-pressure atomizing tower, atomizing and condensing metal liquid drops by adopting high-pressure argon to form spheres, and adjusting the pressure of the argon and the diameter of a nozzle to obtain the bismuth-titanium-manganese-selenium alloy particles with the thickness of 0-2 mm.
3. The method for preparing the bismuth titanium manganese selenium alloy for the environment-friendly bismuth-containing free-cutting steel as claimed in claim 2, wherein the method comprises the following steps: NaCl and CaCl in the step one2And CaO in the second step and the third step is an analytical pure chemical reagent for removing crystal water, and the mass percentages of the CaO and the crystal water are respectively 50-60%, 20-25% and 20-25%.
4. The method for preparing the bismuth titanium manganese selenium alloy for the environment-friendly bismuth-containing free-cutting steel as claimed in claim 3, wherein the method comprises the following steps: the ratio of the CaO adding amount of the first batch to the CaO adding amount of the second batch is 6: 4.
5. the method for preparing the bismuth titanium manganese selenium alloy for the environment-friendly bismuth-containing free-cutting steel as claimed in claim 4, wherein the method comprises the following steps: and after the second batch of CaO is added in the third step, the thickness of the slag is 25-30 mm.
6. The method for preparing the bismuth titanium manganese selenium alloy for the environment-friendly bismuth-containing free-cutting steel as claimed in any one of claims 2 to 5, wherein the method comprises the following steps: the ratio of the addition amount of the first batch of low-carbon manganese blocks to the addition amount of the second batch of low-carbon manganese blocks to the addition amount of the third batch of low-carbon manganese blocks is 1.5: 3.5: and 5, controlling the diameter of the first batch of low-carbon manganese blocks to be 0-5 mm.
7. The method for preparing the bismuth titanium manganese selenium alloy for the environment-friendly bismuth-containing free-cutting steel as claimed in claim 6, wherein the method comprises the following steps: in the fourth step, the argon pressure during atomization is 1-1.5 MPa, and the diameter of the nozzle is 3-3.5 mm.
Technical Field
The invention relates to the technical field of cutting steel alloy production, in particular to a bismuth titanium manganese selenium alloy for environment-friendly bismuth-containing free-cutting steel and a preparation method thereof.
Background
With the development of automation, precision and high speed of machining, especially the development of the automobile industry and the precision instrument industry, the market demand of various precision parts is increasing. Therefore, there is a strong demand for a steel material having excellent machinability to reduce production costs. At present, the free-cutting steel with the best machinability on the market is lead free-cutting steel. However, lead is toxic and is easy to gasify and oxidize when added in the smelting process of the free-cutting steel, and has great harm to human health and production environment. With the increasing environmental protection requirements, the production of lead-containing free-cutting steel is gradually limited. The metal bismuth is considered to be the most promising element to replace lead in the free-cutting steel in recent years because of its physical (low melting point) and chemical properties similar to those of lead (existing in the steel in the form of simple substance, not being dissolved in ferrite, not entering MnS cutting phase), non-toxicity, and its machinability comparable to that of the lead free-cutting steel can be achieved by the presence of a small amount in the free-cutting steel.
The density of titanium was 4.54g/cm3The melting point is 1660 ℃, the boiling point is 3287 ℃, and both the melting point and the boiling point are higher than the temperature of the molten steel in the ordinary refining period. Titanium combines with nitrogen, carbon and the like in steel at high temperature to form fine precipitates of TiN, TiC, Ti (CN) and the like, which hinder grain boundary movement, thereby inhibiting austenite grain growth, and reducing rolling crack generation during reheating and rolling of bismuth-containing free-cutting steel at the temperature of 850-1200 DEG C. When ferrotitanium or sponge titanium is adopted for alloying in the later stage of the refining of the free-cutting steel, the titanium is easy to oxidize, so that the yield is low.
The density of manganese was 7.44g/cm3The melting point is 1244 ℃, the boiling point is 1962 ℃, and the alloy is one of main alloy elements in the free-cutting steel and is generally added into the free-cutting steel molten steel in the form of low-carbon ferromanganese at the end of smelting in a converter or an electric furnace.
The selenium density is 4.81g/cm3The melting point is 221 ℃, the boiling point is 685 ℃, the effect of the MnSe alloy in the free-cutting steel is similar to that of sulfur, a MnSe free-cutting phase is mainly generated, and the MnSe covers the surface of the MnS inclusion, so that the deformability of MnS in the hot rolling process can be reduced, and the MnS in the steel tends to be nearly spherical or spindle-shaped, thereby improving the cutting performance of the steel.
Bismuth plays a major role in lubrication and melt embrittlement in free-cutting steel, making it easier for chips to break and discharge. However, the density of bismuth was 9.78g/cm3The density of the molten steel is higher than 7.5g/cm3The solubility of the bismuth in molten steel is very low, the melting point is 271 ℃, the boiling point is 1564 ℃, and both the melting point and the boiling point are lower than the temperature of the molten steel in the common refining period, so that when the metal bismuth particles or bismuth powder is adopted for alloying in the later refining period of the free-cutting steel, a large amount of smoke dust is generated due to rapid gasification and oxidation of bismuth, the production environment is seriously polluted, the yield of bismuth is low, and the production cost is obviously increased.
Through retrieval, the bismuth-containing free-cutting steel disclosed by Chinese invention patents with publication numbers of CN102978501A, CN103255359A, CN103911550A, CN103388050A, CN 111500822A and the like mainly relates to a preparation method of a bismuth-containing cored wire and a bismuth alloying addition method, the bismuth powder and other metals are mixed and added into the steel only by simple mechanical mixing, so that the problems of low bismuth recovery rate, excessive temperature drop of the molten steel and the like caused by gasification of bismuth due to the boiling point lower than the temperature of the molten steel in a refining period are difficult to be fundamentally solved, and simultaneously, the addition amount of alloys such as bismuth, manganese, titanium, sulfur and the like or cored wires in the smelting process of the bismuth-containing free-cutting steel is larger and more metal iron is brought in, so that the temperature drop of the molten steel is excessive.
Disclosure of Invention
1. Technical problem to be solved by the invention
The invention aims to overcome the problem of low bismuth recovery rate due to easy gasification in the industrial production of bismuth-containing free-cutting steel in the prior art, and provides an environment-friendly bismuth titanium manganese selenium alloy for the bismuth-containing free-cutting steel and a preparation method thereof; by designing and optimizing the components of the bismuth titanium manganese selenium alloy system, the invention not only ensures the moderate melting point of the bismuth titanium manganese selenium alloy, but also obviously improves the gasification temperature of the bismuth titanium manganese selenium alloy, thereby effectively avoiding the problem of low recovery rate of bismuth caused by easy gasification; in addition, in the preparation process, the gasification and oxidation in the smelting process of the bismuth-titanium-manganese-selenium alloy are effectively inhibited by adopting a staged heating process of an induction furnace and controlling the adding amount, adding sequence and slag former components of the raw materials of bismuth, manganese, titanium and selenium.
2. Technical scheme
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
the bismuth titanium manganese selenium alloy for the environment-friendly bismuth-containing free-cutting steel comprises, by weight, 40% -50%, 5% -10%, 35-45%, 5% -10% and 0% -0.1% of Bi/Ti, wherein Bi/Ti is not less than 5 and not more than 8.
The invention relates to a preparation method of a bismuth titanium manganese selenium alloy for environment-friendly bismuth-containing free-cutting steel, which comprises the following steps:
step one, melting and heating high-purity bismuth blocks (not less than 99.9%) and selenium particles through induction melting, adding a first batch of low-carbon manganese blocks into a melt when the melt is heated to 600-650 ℃, and then adding NaCl and CaCl into the surface layer of the low-carbon manganese blocks2Covering and slagging are carried out;
step two, when the temperature of the melt rises to 955-980 ℃, poking a slag layer, adding a second batch of low-carbon manganese blocks into the melt, and then adding a first batch of CaO into the slag;
step three, when the temperature of the melt rises to 1030-1100 ℃, poking a slag layer, adding a third batch of low-carbon manganese blocks and titanium sponge into the melt, and then adding a second batch of CaO into the slag;
fourthly, after the temperature of the melt is increased to 1165-1205 ℃, removing slag on the surface layer of the melt, then injecting the alloy melt into a high-pressure atomizing tower, atomizing and condensing metal liquid drops by adopting high-pressure argon to form spheres, and adjusting the pressure of the argon and the diameter of a nozzle to obtain the bismuth-titanium-manganese-selenium alloy particles with the thickness of 0-2 mm.
As a further improvement of the invention, NaCl and CaCl are added in the first step2And CaO in the second step and the third step is an analytical pure chemical reagent for removing crystal water, and the mass percentages of the CaO and the crystal water are respectively 50-60%, 20-25% and 20-25%.
As a further improvement of the invention, the ratio of the added amounts of the CaO in the first batch to the added amount of the CaO in the second batch is 6: 4.
as a further improvement of the invention, after the second batch of CaO is added in the third step, the thickness of the slag is 25-30 mm.
As a further improvement of the invention, the ratio of the addition amount of the first batch of low-carbon manganese blocks to the addition amount of the second batch of low-carbon manganese blocks to the addition amount of the third batch of low-carbon manganese blocks is 1.5: 3.5: and 5, controlling the diameter of the first batch of low-carbon manganese blocks to be 0-5 mm.
In a further improvement of the present invention, in the fourth step, the argon pressure during atomization is 1 to 1.5MPa, and the diameter of the nozzle is 3 to 3.5 mm.
3. Advantageous effects
Compared with the prior art, the technical scheme provided by the invention has the following remarkable effects:
(1) according to the bismuth titanium manganese selenium alloy for the environment-friendly bismuth-containing free-cutting steel, the melting point of the alloy is effectively adjusted by designing and optimizing the components of a bismuth titanium manganese selenium alloy system, and the bismuth titanium manganese selenium alloy is added into the steel in an alloy form in the process of preparing the bismuth-containing free-cutting steel, so that the problem of low recovery rate of bismuth caused by easy gasification is effectively avoided;
(2) the bismuth-titanium-manganese-selenium alloy for the environment-friendly bismuth-containing free-cutting steel comprises bismuth and titanium, the machinability of the steel is improved through the bismuth, the thermoplasticity of the steel is improved through the titanium, in order to ensure that the bismuth-containing free-cutting steel has excellent machinability and simultaneously has high thermoplasticity, but in the bismuth-containing free-cutting steel, the content of titanium fluctuates along with the fluctuation of the content of bismuth, the low Bi/Ti content means the content of titanium is high, the overhigh titanium causes the deterioration of the machinability of the steel, and meanwhile, the titanium can be combined with Se to generate TiSe to inhibit the generation of BiSe, so that the gasification of the bismuth is promoted; the high Bi/Ti ratio means that the content of titanium is high, and the excessively low titanium does not have the effect of improving the thermoplasticity of the steel, so that the ratio of Bi to Ti is reasonably controlled when the Bi and Ti components in the alloy are optimized.
(3) According to the preparation method of the bismuth-titanium-manganese-selenium alloy for the environment-friendly bismuth-containing free-cutting steel, the gasification and oxidation of the bismuth-titanium-manganese-selenium alloy smelting process are effectively inhibited by adopting the induction furnace staged heating process and controlling the adding sequence of the raw materials of bismuth, manganese, titanium and selenium and the components of the slag former in the preparation process, the whole alloy smelting time is short, the burning loss is less, and the smoke pollution is less; in addition, the gasification of bismuth and selenium at high temperature is effectively inhibited through the chemical composition of manganese and titanium, and the obtained bismuth-titanium-manganese-selenium alloy particles have high alloy yield and low molten steel temperature when being used for the alloying treatment of the environment-friendly bismuth-containing free-cutting steel at high temperature (1600-1650 ℃);
(4) according to the preparation method of the bismuth-titanium-manganese-selenium alloy for the environment-friendly bismuth-containing free-cutting steel, the slagging agent and the thickness of the furnace slag are controlled, so that on one hand, uniform stirring is facilitated, on the other hand, gasification and oxidation of bismuth and selenium are effectively inhibited, and the content of bismuth and selenium in the alloy is effectively controlled; once the slag layer is too thick, the slag is stirred and mixed for too long time, powdery NaCl, CaCl2 and CaO on the surface layer of the slag are difficult to melt and crystallize, and dust pollution and raw material waste are caused;
(5) according to the preparation method of the bismuth-titanium-manganese-selenium alloy for the environment-friendly bismuth-containing free-cutting steel, disclosed by the invention, when the first batch of low-carbon manganese blocks are added, the melt temperature is lower, and the diameter of the first batch of low-carbon manganese blocks is controlled, so that the melting rate of the low-carbon manganese blocks is high, the manganese content in the bismuth-selenium alloy can be promoted to be rapidly increased in the heating process, MnBi and MnSe are formed, and the gasification and oxidation of bismuth and selenium are inhibited; in addition, because the saturated vapor pressure of bismuth is lower, the higher the temperature is, the higher the gasification tendency of bismuth is, therefore the invention adopts and adds low carbon ferromanganese in batches and can obviously inhibit the gasification and oxidation of bismuth in the temperature rise process of the alloy melt.
Drawings
FIG. 1 is a scanning electron microscope image of composite inclusions formed by adding bismuth titanium manganese selenium alloy particles produced in example 1 to an environment-friendly bismuth-containing free-cutting steel;
FIG. 2 is a spectrum of an energy spectrum analysis of composite inclusions formed by adding bismuth titanium manganese selenium alloy particles produced in example 1 to an environmentally friendly bismuth-containing free-cutting steel;
FIG. 3 is a table showing the chemical compositions of composite inclusions formed by adding bismuth titanium manganese selenium alloy particles produced in example 1 to an environmentally friendly bismuth-containing free-cutting steel.
FIG. 4 is a field diagram of feeding bismuth powder and iron powder cored wire of bismuth-containing free-cutting steel at 1637 deg.C by adopting the prior art.
FIG. 5 is a field diagram of a bismuth-containing free-cutting steel fed into a cored wire of bismuth titanium manganese selenium alloy particles of example 1 at 1643 ℃.
Detailed Description
For a further understanding of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings and examples.
Example 1
The bismuth titanium manganese selenium alloy for the environment-friendly bismuth-containing free-cutting steel of the embodiment takes 1000kg of total amount as an example, and the raw materials and the mixture ratio thereof are 400kg of high-purity bismuth block, 450kg of low-carbon manganese block, 100kg of selenium particles and 50kg of sponge titanium, namely the bismuth titanium manganese selenium alloy comprises the following chemical components: bi: ti: mn: se: c and unavoidable impurities (in mass percent) 40%: 5%: 44.95%: 10%: 0.05 percent. Setting the total amount of the slag former to be 20kg based on the inner diameter of the furnace lining being 600mm and the thickness of the slag layer being 25-30 mm, wherein NaCl10kg and CaCl25kg and 5kg of CaO, namely chemical components (by mass percent) of the slagging agent are NaCl: CaCl2：CaO＝50％：25％：25％。
The preparation method of the bismuth titanium manganese selenium alloy for the environment-friendly bismuth-containing free-cutting steel comprises the following steps: placing 400kg of high-purity bismuth block and 100kg of selenium particles into a crucible of an induction furnace to heat along with the furnace, measuring the temperature (623 ℃) when bismuth and selenium alloy are melted and heated until smoke gas is emitted, rapidly adding 67.5kg of low-carbon manganese block with the diameter less than 5mm, and then adding 10kg of NaCl and 5kg of CaCl into the surface layer of the melt2And carrying out slagging.
And (3) observing the melting condition of the low-carbon manganese blocks in the heating process, measuring the temperature (the temperature is 920 ℃) when the low-carbon manganese blocks are completely melted, adding 157.5kg of second low-carbon manganese blocks into the alloy melt when the temperature of the alloy melt is raised to 970-980 ℃, adding 3kg of first CaO into the slag, and uniformly stirring the slag by using an iron rod.
And measuring the temperature (the temperature is 1038 ℃) when the second batch of low-carbon manganese blocks are melted, adding 225kg and 50kg of sponge titanium into the alloy melt when the temperature of the alloy melt is increased to 1088-1100 ℃, adding 2kg of CaO into the slag, and uniformly stirring the slag by using an iron rod.
Measuring the temperature (the temperature is 1114 ℃) when the third batch of low-carbon manganese blocks and titanium sponge are melted, raising the temperature of the alloy melt to 1195-1205 ℃, removing slag on the surface layer of the melt, then injecting the alloy melt into a high-pressure atomizing tower, and adjusting the argon pressure and the nozzle diameter of the high-pressure atomizing device to be 1MPa and 3mm respectively to obtain bismuth titanium manganese selenium alloy particles with different particle size proportions between 0mm and 2mm in diameter, wherein 0-0.5 mm accounts for 61%, 0.5-1 mm accounts for 32%, and 1-2 mm accounts for 7%.
The bismuth titanium manganese selenium alloy particles obtained by the preparation method of the bismuth titanium manganese selenium alloy for the environment-friendly bismuth-containing free-cutting steel are applied to the bismuth-containing free-cutting steel, the shape and appearance of a scanning electron microscope are shown in figure 1, the energy spectrum analysis spectrum is shown in figure 2, and the chemical composition table is shown in figure 3.
Example 2
In the present embodiment, for example, the total amount of the bismuth-titanium-manganese-selenium alloy is 1000kg, and the raw material mixture ratio is 450kg of high-purity bismuth block, 390kg of low-carbon manganese block, 80kg of selenium grain, and 80kg of sponge titanium, that is, the bismuth-titanium-manganese-selenium alloy comprises the following chemical components: bi: ti: mn: se: c and unavoidable impurities (in mass percent) 45%: 8%: 38.96%: 8%: 0.04 percent. Setting the total amount of the slag former to be 18kg based on the inner diameter of the furnace lining being 600mm and the thickness of the slag layer being 25-30 mm, wherein NaCl is 9.9kg, CaCl is24.14kg, CaO 3.96kg, namely, chemical components (by mass percent) of the slagging agent are NaCl: CaCl2：CaO＝55％：23％：22％。
The preparation method of the bismuth titanium manganese selenium alloy for the environment-friendly bismuth-containing free-cutting steel comprises the following steps: putting 450kg of high-purity bismuth block and 80kg of selenium granulesHeating in an induction furnace crucible, measuring temperature (627 deg.C) when bismuth and selenium alloy are molten and heated until smoke is emitted, rapidly adding 58.5kg of low-carbon manganese blocks with diameter less than 5mm, and adding 9.9kg of NaCl and 4.14kg of CaCl on the surface layer of the melt2And carrying out slagging.
And (3) observing the melting condition of the low-carbon manganese blocks in the heating process, measuring the temperature (the temperature is 908 ℃) when the low-carbon manganese blocks are completely melted, adding 136.5kg of second low-carbon manganese blocks into the alloy melt when the temperature of the alloy melt is increased to 960-975 ℃, adding 136.38kg of first CaO2.38kg of slag, and uniformly stirring the slag by using an iron rod.
Measuring the temperature (the temperature is 985 ℃) when the second batch of low-carbon manganese blocks are melted, adding 195kg and 80kg of sponge titanium into the alloy melt when the temperature of the alloy melt rises to 1040-1050 ℃, adding 1.58kg of CaO into the slag, and uniformly stirring the slag by using an iron rod.
Measuring the temperature (the temperature is 1096 ℃) when the third batch of low-carbon manganese blocks and titanium sponge are melted, raising the temperature of the alloy melt to 1180-1190 ℃, removing slag on the surface layer of the melt, then injecting the alloy melt into a high-pressure atomizing tower, and adjusting the argon pressure and the nozzle diameter of the high-pressure atomizing device to be 1.2MPa and 3.2mm respectively to obtain bismuth titanium manganese selenium alloy particles with different particle size proportions and diameters of 0-2 mm, wherein 0-0.5 mm accounts for 64%, 0.5-1 mm accounts for 28%, and 1-2 mm accounts for 8%.
Example 3
In the present embodiment, for example, the total amount of the bismuth-titanium-manganese-selenium alloy is 1000kg, and the raw material mixture ratio is 500kg of high-purity bismuth block, 350kg of low-carbon manganese block, 50kg of selenium grain, and 100kg of sponge titanium, that is, the bismuth-titanium-manganese-selenium alloy has the following chemical components: bi: ti: mn: se: c and unavoidable impurities (in mass percent) 50%: 10%: 34.96%: 5%: 0.04 percent. Setting the total amount of the slag former to be 15kg based on the inner diameter of the furnace lining being 600mm and the thickness of the slag layer being 25-30 mm, wherein NaCl 9kg and CaCl23kg and 3kg of CaO, namely the chemical components (by mass percent) of the slag former are NaCl: CaCl2：CaO＝60％：20％：20％。
The preparation of the bismuth titanium manganese selenium alloy for the environment-friendly bismuth-containing free-cutting steel of the embodimentThe preparation method comprises the following steps: 500kg of high-purity bismuth block and 50kg of selenium particles are put into a crucible of an induction furnace to be heated along with the furnace, when the bismuth and selenium alloy is melted and heated until smoke is emitted, the temperature is measured (the temperature is 632 ℃), 52.5kg of low-carbon manganese block with the diameter less than 5mm is rapidly added, and then 9kg of NaCl and 3kg of CaCl are added into the surface layer of the melt2And carrying out slagging.
And (3) observing the melting condition of the low-carbon manganese blocks in the temperature rising process, measuring the temperature (the temperature is 894 ℃) when the low-carbon manganese blocks are completely melted, adding 122.5kg of second low-carbon manganese blocks into the alloy melt when the temperature of the alloy melt rises to 954-964 ℃, adding the first CaO1.8kg of slag, and uniformly stirring the slag by using an iron rod.
Measuring the temperature (the temperature is 967 ℃) when the second batch of low-carbon manganese blocks are melted, adding 175kg and 100kg of sponge titanium of the third batch of low-carbon manganese blocks into the alloy melt when the temperature of the alloy melt rises to 1030-1040 ℃, adding 1.2kg of CaO into the slag, and uniformly stirring the slag by using an iron rod.
Measuring the temperature (1075 ℃) when the third batch of low-carbon manganese blocks and titanium sponge are melted, raising the temperature of the alloy melt to 1165-1175 ℃, removing slag on the surface layer of the melt, then injecting the alloy melt into a high-pressure atomizing tower, and adjusting the argon pressure and the nozzle diameter of the high-pressure atomizing device to be 1.5MPa and 3.5mm respectively to obtain bismuth titanium manganese selenium alloy particles with different particle size proportions between 0mm and 2mm in diameter, wherein 0-0.5 mm accounts for 60%, 0.5-1 mm accounts for 30%, and 1-2 mm accounts for 10%.
It is worth to be noted that, in the process of smelting the bismuth titanium manganese selenium alloy in the embodiment, the low-carbon manganese blocks are added in three batches, specifically, the adding amount of the first batch of low-carbon manganese blocks is 15% of the total adding amount, the second batch of low-carbon manganese blocks are added at a temperature 50-70 ℃ higher than the complete melting temperature of the alloy melt, the third batch of low-carbon manganese blocks are added at a temperature 50-70 ℃ higher than the complete melting temperature of the alloy melt, and the adding amounts of the second batch of low-carbon manganese blocks and the third batch of low-carbon manganese blocks are 35% and 50% of the total adding amount respectively. The low-carbon manganese blocks are added in three batches, so that the alloy melt after the low-carbon manganese blocks are added is ensured to have a liquid phase in a certain proportion, the melting rate of the low-carbon manganese blocks is improved, the flowing temperature of the low-carbon manganese blocks in the induction heating process is faster than that of a static conductive object, and the low-carbon manganese blocks which are rapidly melted can promote rapid and uniform compounding of bismuth and manganese in the alloy melt in the temperature rising process, so that gasification and oxidation of bismuth are effectively inhibited.
Furthermore, because the temperature of the bismuth-selenium alloy melt is lower when the first batch of low-carbon manganese blocks are added, the melting rate of small-sized low-carbon manganese blocks is higher, the manganese content in the bismuth-selenium alloy can be promoted to be rapidly increased in the temperature rise process, and MnBi and MnSe are formed, so that the gasification and oxidation of bismuth and selenium are inhibited, and the adding amount and the diameter of the first batch of low-carbon manganese blocks are controlled.
In addition, CaO is added in two batches, the thickness of the slag is controlled to be 25-30 mm, and the adding amount is controlled to be 60% and 40% of the total adding amount respectively. The purpose of controlling the CaO to be added in two batches is to adjust the melting point and the viscosity of the slag in stages according to the temperature rise condition of the alloy melt, so that the slag layer is convenient to be separated when the alloy is added, and the oxidation and the gasification of the alloy melt can be effectively prevented.
In order to show the effect of adding multiple batches, the total amount (1000kg) of the bismuth titanium manganese selenium alloy, the raw material ratio (Bi: Ti: Mn: Se: C and unavoidable impurities: 40%: 5%: 44.95%: 10%: 0.05%) and the slag former component (NaCl: CaCl) were designed to be the same for comparative examples 1 to 10 and inventive examples 1 and 2 in Table 12: CaO 50%: 25%: 25%) and the time points of the single additions of the low carbon manganese blocks and CaO were the same as the time points of the additions of the first batch of low carbon manganese blocks and the first batch of CaO in example 1.
TABLE 1 Industrial Effect of smelting bismuth titanium manganese selenium alloy melt by different smelting processes (evaluation period of smelting effect is from the beginning of feeding alloy raw materials to the complete melting)
As can be seen from comparative examples 1-10, invention examples 1 and invention examples 2, the smelting process of the bismuth titanium manganese selenium alloy adopts a smelting mode that low-carbon manganese blocks are added in three batches, the thickness of the furnace slag is controlled to be 25-30 mm, and CaO is added in two batches, so that the smelting time is reduced by 11-12 min, the recovery rates of bismuth and selenium are improved by more than 15%, the fluidity of the furnace slag is obviously improved, and the smoke emission is obviously reduced.
In order to show the effect of adding bismuth titanium manganese selenium alloy particles to bismuth-containing free-cutting steel, table 2 shows the effect of industrial application of bismuth titanium manganese selenium particle cored wires of example 1 (invention example 3, invention example 4 and invention example 5) and bismuth titanium manganese selenium particle cored wires of example 1 (invention example 3, invention example 4 and invention example 5) in which bismuth-containing free-cutting steel was fed with bismuth iron powder cored wires of publication No. CN103388050A (comparative example 11, comparative example 12 and comparative example 13, Bi: Fe ═ 40%: 60%), bismuth manganese iron particle cored wires of publication No. CN102978501A (comparative example 14, comparative example 15 and comparative example 16, Bi: Mn: Fe ═ 45%: 47%: 8%).
TABLE 2 effect of industrial application of free-cutting steel to different bismuth alloy cored wires
As can be seen from comparative examples 11 to 16 and invention examples 3 to 5, when the bismuth titanium manganese selenium particles are prepared into cored wires and fed into free-cutting steel, the recovery rate of bismuth is remarkably improved to 77 to 85 percent, the temperature drop of molten steel is reduced to 24 to 28 ℃, and smoke pollution is remarkably reduced.
By combining the figures 4 and 5, it can be seen that the smoke pollution generated by adding the bismuth titanium manganese selenium alloy prepared by the invention into the bismuth-containing free-cutting steel is obviously reduced.
The present invention and its embodiments have been described above schematically, without limitation, and what is shown in the drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. Therefore, if the person skilled in the art receives the teaching, without departing from the spirit of the invention, the person skilled in the art shall not inventively design the similar structural modes and embodiments to the technical solution, but shall fall within the scope of the invention.