CN117778871A - Method for preparing high-performance gray cast iron by adding piston scrap iron - Google Patents
Method for preparing high-performance gray cast iron by adding piston scrap iron Download PDFInfo
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- 229910052742 iron Inorganic materials 0.000 title claims abstract description 110
- 229910001060 Gray iron Inorganic materials 0.000 title claims abstract description 59
- 238000000034 method Methods 0.000 title claims abstract description 30
- 239000000463 material Substances 0.000 claims abstract description 65
- 238000005266 casting Methods 0.000 claims abstract description 49
- 229910052787 antimony Inorganic materials 0.000 claims abstract description 28
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 23
- 238000011081 inoculation Methods 0.000 claims abstract description 23
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 claims abstract description 22
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 20
- 229910000805 Pig iron Inorganic materials 0.000 claims abstract description 17
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- 239000002054 inoculum Substances 0.000 claims abstract description 7
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 claims abstract description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 27
- 229910002804 graphite Inorganic materials 0.000 claims description 24
- 239000010439 graphite Substances 0.000 claims description 24
- 238000004519 manufacturing process Methods 0.000 claims description 23
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- 230000005496 eutectics Effects 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 3
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- 229910001018 Cast iron Inorganic materials 0.000 abstract description 32
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- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
The invention belongs to the technical field of casting material processing, and discloses a method for preparing high-performance gray cast iron by adding piston scrap iron. Pouring scrap steel, cast pig iron, piston scrap iron, ferrosilicon, ferromanganese and carburant into an electric furnace for smelting, adding antimony for smelting after more than three slag forming processes, and fully diffusing the antimony; adding a ferrosilicon inoculant into molten iron for inoculation treatment, controlling the temperature of the molten iron to be more than 1490 ℃ after the spectral detection control component composition reaches the standard, discharging, transferring to a casting table for casting, and controlling the initial casting temperature to be 1405-1425 ℃ to obtain the high-performance gray cast iron material. According to the invention, by adding the piston scrap iron into the casting raw material, the alloy cast iron scrap iron with rich depreciation can be utilized in a value-added manner, and Cr, ni and Mo elements in the scrap iron can play a role in microalloying in the material of the gray cast iron piece product, so that the processing performance of the material of the gray cast iron piece product and the service performance of the material are better.
Description
Technical Field
The invention belongs to the technical field of casting material processing, and particularly relates to a method for preparing high-performance gray cast iron by adding piston scrap iron.
Background
The heart compressor of air conditioner refrigerating system is mainly formed from flange, cylinder, crankshaft and piston. The grey cast iron parts of air conditioner compressors are often referred to as: upper (lower) flanges (also known as primary and secondary bearings or upper and lower supports), cylinders, and other cast iron parts.
Because the air conditioning refrigeration system is in refrigeration operation, the components within the air conditioning compressor are substantially in a high speed relative motion. Clearly, there are high specific requirements on the precision of these parts and the performance characteristics of the individual materials. Therefore, to ensure the performance of the compressor, the casting suppliers must produce these parts with casting product quality meeting relevant quality specifications.
In general, the service performance of the upper flange, the lower flange and the cylinder part is required to meet the standard of HT250 materials, have enough strength, hardness and wear resistance, have easy cutting property in the production and processing process and have good air tightness in use. Moreover, the air conditioner compressor is required to meet the requirements of achieving a specified service life and having a specified good performance.
In addition, with the increase of market competition of air conditioner compressor parts in recent years, the capacity of the air conditioner compressor parts market gradually becomes saturated, and profit margins of related casting products are also gradually extruded. In the manufacture of these cast products, a little bit of care may affect the profit margin of the product.
Therefore, the method is suitable for market change, stabilizes the product quality, improves the service performance of the product, pays attention to environmental protection, optimizes and improves the resource utilization rate, and has obvious significance in further measures such as cost reduction and efficiency improvement.
The piston scrap iron is scrap iron generated by cutting during machining of the piston, and because the piston is various in size specification, for the convenience of production, casting dies are basically produced by covering a plurality of size specifications with one die. Therefore, the total cutting amount when machining the piston is relatively large, and the amount of scrap iron generated is also relatively large. The scrap iron produced every day is partially returned to the piston furnace material for blank production in a furnace material returning mode, and the rest part of scrap iron is left out.
Although the surplus scrap iron is the scrap iron of the alloy iron casting piston, the alloy iron casting piston contains a certain proportion of noble metal elements of Cr, ni and Mo. However, when the scrap iron is sold to the outside, the price of the scrap iron entering the market is lower than the price of common iron filings, and the price of common pig iron is only about 1/2. The scrap iron is used for externally discount treatment, so that the waste of precious metal resources is avoided, and the benefit of enterprises is not met.
Therefore, in the production of the compressor iron castings, the surplus piston scrap iron is reasonably utilized and digested, and the method has long-term positive significance for cost reduction and efficiency improvement of enterprises.
Because the structural size of the compressor iron casting product and the requirement of the material grade HT250 are determined, the requirement of adding Cr, ni and Mo elements is basically not existed in the production of the casting. Therefore, the Cr, ni and Mo elements in the conventional product materials belong to the self-contained components in pig iron and scrap steel, and the contents of the elements are generally low, and are approximately as follows: 0.05 to 0.07 percent of Cr, 0.001 to 0.01 percent of Ni and 0.001 to 0.01 percent of Mo. Therefore, the alloying effect is negligible for the original content in the cast iron material.
Patent CN 101725504A discloses a refrigerant compressor, wherein the matrix of the crankshaft to be powered is ferrite of 5% or less, and the rest is graphite flake cast iron containing Cr, mo or Ni, which is composed of pearlite. Alternatively, the base body of the crankshaft is pearlite having an area ratio of 50% or more, and the rest of the base body is spheroidal graphite cast iron composed of ferrite. The main bearing for supporting the crankshaft is made of a graphite flake cast iron (gray cast iron) containing no alloy, and the graphite on the upper part of the main bearing is eutectic graphite, and pearlite is present in the matrix at 30% to 95%. Although the patent discloses that Cr, mo or Ni is introduced into pearlite, in the cast iron field, the content ratio of a material matrix and a structure improver has a key effect on the product performance, and the corresponding casting process often exceeds or falls below a specified amount, so that not only can the improvement effect be achieved, but also the material performance is deteriorated, and the improvement effect is not achieved.
Patent CN 102851575A discloses an oxidation resistant alloyed gray cast iron and a method for manufacturing the same, the cast iron comprising the following components in mass percent: c:3.0 to 3.2 percent of Si:1.8 to 2.0 percent of Mn:0.50 to 0.70 percent of Cr:0.10 to 0.50 percent of Ni:0.20 to 0.30 percent of Mo:0.30 to 0.50 percent of Al:0.5 to 3.0 percent of Sr:0.05 to 0.08 percent of Zn: 0.005-0.015% and the balance of Fe and unavoidable impurities. The manufacturing method comprises the steps of raw material smelting, inoculation and pouring, wherein the tapping temperature after smelting is 1450-1550 ℃, and slag skimming and pouring are carried out after molten iron is poured in a ladle and stream inoculation. Although Mo, ni and Cr alloy elements have the effect of stabilizing pearlite, the alloy elements are mainly used for manufacturing glass dies and light alloy metal mold casting dies which bear high-temperature forming liquid thermal shock and cold-hot alternating stress for a long time, and have obvious differences with the performance requirements of internal parts of an air conditioner compressor, so that the composition of the components is different, such as the key C content is relatively low, the added content of Mo, ni and Cr is high, the mechanical properties of the alloy elements are obviously improved, but the mechanical processability of the alloy elements is poor, the material cost is high, and the alloy elements are very unfavorable for casting products of the internal parts of the air conditioner compressor, such as flanges, cylinders, crankshafts and pistons, which need fine cutting, and the alloy elements are reduced in cost and enhanced in enterprises.
Patent CN 105543640A discloses a antifriction cast iron for automobile brake discs, which comprises the following chemical components: c:3-3.4%, si:1.6-2.6%, mn:0.6-1.1%, P is less than or equal to 0.15%, S is less than 0.12%, cr:1.5-2.5%, ni:0.3-0.6%, mo:0.1-0.3%, and the balance of Fe. The raw materials of the antifriction cast iron are added with alloy elements such as Cr, ni, mo and the like, so that the toughness of the cast iron is greatly improved, the mechanical property of the antifriction cast iron is improved, the wear resistance of the antifriction cast iron can reach 3 times that of common HT200 gray cast iron, the mechanical requirement of an automobile brake disc can be met, and the problems that a plurality of cast irons are large in brittleness and cannot bear strong impact are solved. However, the patent also has the problems of higher Mo, ni and Cr addition, higher cost and poorer mechanical processing property of the material.
Disclosure of Invention
In view of the above drawbacks and shortcomings of the prior art, a primary object of the present invention is to provide a method for preparing high performance gray cast iron by adding piston scrap iron.
Another object of the present invention is to provide a high-performance gray cast iron prepared by the above method.
It is a further object of the present invention to provide the use of the above-described high performance gray cast iron for the manufacture of air conditioner compressor cast iron parts.
The preparation method and the obtained product of the invention reasonably integrate and utilize partial piston scrap iron resources which are redundant in the production process, avoid rust loss generated during the storage period, shorten the recycling time of material resources and accelerate the improvement of the utilization efficiency of circular economy. The valuable material resource is fully utilized, and the waste is turned into wealth, thereby being beneficial to further reducing the consumption and saving the cost. On the other hand, when the gray cast iron piece is produced, the good effect of improving the service performance and the processing performance of the cast product can be achieved by adding the surplus alloy scrap iron into the ingredients. The compressor iron casting product produced by the invention finally has unique leading competitive advantages in increasingly competitive supply markets.
The invention aims at realizing the following technical scheme:
a method for preparing high-performance gray cast iron by adding piston scrap iron comprises the following preparation steps:
(1) Pouring scrap steel, cast pig iron, piston scrap iron, ferrosilicon, ferromanganese and carburant into an electric furnace for smelting, adding antimony for smelting after more than three slag forming processes, and fully diffusing the antimony; the spectrum detection control is formed into groups: 3.25 to 3.45 percent of C, 1.75 to 1.90 percent of Si, 0.65 to 0.85 percent of Mn, less than 0.12 percent of P, less than 0.15 percent of S, 0.030 to 0.035 percent of Sb, 0.08 to 0.133 percent of Cr, 0.013 to 0.038 percent of Ni, 0.008 to 0.028 percent of Mo and the balance of Fe; the piston scrap iron is scrap iron generated by cutting during machining of the piston, and the chemical composition of the piston scrap iron comprises the following components: 0.65 to 0.85 percent of Cr, 0.15 to 0.45 percent of Ni and 0.1 to 0.4 percent of Mo;
(2) Adding a ferrosilicon inoculant into molten iron in the step (1) for inoculation; the spectrum detection control is formed into groups: 3.25 to 3.45 percent of C, 2.20 to 2.40 percent of Si, 0.65 to 0.85 percent of Mn, less than 0.12 percent of P, less than 0.15 percent of S, 0.030 to 0.035 percent of Sb, 0.08 to 0.133 percent of Cr, 0.013 to 0.038 percent of Ni, 0.008 to 0.028 percent of Mo and the balance of Fe;
(3) And tapping the molten iron at the temperature of more than 1490 ℃, transferring to a casting table for casting, and controlling the initial casting temperature to 1405-1425 ℃ to obtain the high-performance gray cast iron material.
Further, the mass percentage of the added piston scrap iron in the step (1) is 3-20%.
Further, in the step (2), at least one of ladle inoculation, ladle inoculation and stream inoculation is adopted for inoculation; wherein the inoculation adding amount in the ladle is 0.15% of the molten iron mass, the ladle inoculation adding amount is 0.3% of the molten iron mass, and the stream inoculation adding amount is 3g/s.
The high-performance gray cast iron is prepared by the method; the high-performance gray cast iron comprises the following components: 3.25 to 3.45 percent of C, 2.20 to 2.40 percent of Si, 0.65 to 0.85 percent of Mn, less than 0.12 percent of P, less than 0.15 percent of S, 0.030 to 0.035 percent of Sb, 0.08 to 0.133 percent of Cr, 0.013 to 0.038 percent of Ni, 0.008 to 0.028 percent of Mo and the balance of Fe.
Further, the high-performance gray cast iron graphite is A-type, the graphite length is 4-5 grade, the pearlite content is more than or equal to 98%, the ferrite content is less than 2%, the carbide is less than 1%, the phosphor eutectic is less than 0.5%, the hardness HB range is 163-255, and the tensile strength is more than or equal to 250Mpa.
The application of the high-performance gray cast iron in preparing cast iron parts of air conditioner compressors.
Further, the air conditioner compressor iron casting part comprises a main bearing, an auxiliary bearing, a cylinder and a piston.
The principle of the invention is as follows: in a certain content range, cr element has a refining effect on cast iron graphite, and has a promoting and refining effect on pearlite of cast iron matrix tissues; the Ni element has a refining effect on cast iron graphite, has a promoting, strong stabilizing and refining effect on pearlite of a cast iron matrix structure, and reduces the shrinkage tendency of the material; mo element has refining effect on cast iron graphite, and has promoting, stabilizing and refining effects on pearlite of cast iron matrix structure, and improves shrinkage tendency of the material. And further, the machining performance of the material can be further improved through the combined action of Cr, ni and Mo in a specific content range. Therefore, by utilizing the combined action characteristic of Cr, ni and Mo elements in the cast iron material, the effects of grain refinement, graphite refinement and pearlite stabilization can be achieved for the cast iron material. Thereby playing a role in comprehensively strengthening the cast iron material matrix and promoting the hardness, strength, wear resistance, compactness and relative easy cutting property of the cast iron material to be improved. The pearlite content is not lower than 98%, the tensile strength reaches 268-274 MPa, the processing performance of the casting is further improved, and the average service life of the cutter is prolonged from 80-100 pieces/edge to 120-140 pieces/edge.
Compared with the prior art, the invention has the beneficial effects that:
(1) According to the invention, by adding the piston scrap iron into the casting raw material, the alloy cast iron scrap iron with rich depreciation can be utilized in a value-added manner, and Cr, ni and Mo elements in the scrap iron can play a role in microalloying in the material of the gray cast iron piece product, so that the processing performance of the material of the gray cast iron piece product and the service performance of the material are better. The method is characterized in that: 1. graphite and pearlite in a matrix structure of the product material can be further refined and stabilized, so that the manufacturing production can more effectively obtain a metallographic structure conforming to the material grade; 2. the product can obtain a more compact metal structure, so that the hardness and strength of the metal material can be optimally improved, and the wear resistance and air tightness of the metal material can be improved; 3. the mechanical processing property of the product material can be further improved; 4. the method can reasonably utilize and add value of the surplus piston scrap iron, is favorable for further reducing consumption and saving cost, accords with the development policy of national 'circular economy', can treat the problems of storage and value-added circular utilization of the surplus piston scrap iron for a long time, and ensures that the turnover utilization of the material is more economical.
(2) According to the invention, a certain amount of antimony element with lower cost is added to replace noble metal elements such as common tin and/or copper, so that the mechanical property and the machining property of the gray cast iron material can be obviously improved, and the production cost is reduced.
Detailed Description
The present invention will be described in further detail with reference to examples, but embodiments of the present invention are not limited thereto.
In the following examples, piston scrap iron is derived from scrap iron generated by cutting during the process of machining pistons (about 335 ten thousand pieces of cast blanks, about 837.5 tons) in the production of net piston products by companies, and the remaining part of scrap iron (about 200 tons per month) is left for the production of high-performance gray cast iron according to the present invention, except for a part of scrap iron which is returned to be added to the piston charge in a furnace charge mode for blank production. The piston scrap iron used in the following examples contained 0.78% Cr, 0.28% Ni and 0.2% Mo as measured by composition.
Performance testing in the following examples included mainly brinell hardness (GB/T9439-2010), tensile strength (GB/T9439-2010,sample) and easy workability (tool life during machining).
Example 1
The method for preparing high-performance gray cast iron (flange (support, bearing and disc cylinder)) by adding piston scrap iron in the embodiment comprises the following preparation steps:
(1) Pouring scrap steel, cast pig iron, piston scrap iron, ferrosilicon, ferromanganese and carburant into an electric furnace for smelting, adding antimony for smelting after more than three slag forming processes, and fully diffusing the antimony; the spectrum detection control is formed into groups: 3.4% of C, 1.9% of Si, 0.65% of Mn, less than 0.12% of P, less than 0.15% of S, 0.03% of Sb, 0.08% of Cr, 0.02% of Ni, 0.01% of Mo and the balance of Fe.
(2) Adding 75 ferrosilicon inoculant accounting for 0.15% of the molten iron mass into the ladle in the step (1) for ladle inoculation treatment for 8min; the spectrum detection control is formed into groups: 3.4% of C, 2.4% of Si, 0.65% of Mn, less than 0.12% of P, less than 0.15% of S, 0.03% of Sb, 0.08% of Cr, 0.02% of Ni, 0.01% of Mo and the balance of Fe.
(3) Tapping the molten iron at the temperature of more than 1490 ℃, transferring to a casting table for casting, and controlling the initial casting temperature to 1420+/-5 ℃ to obtain the high-performance gray cast iron material.
Taking the condition that no piston scrap iron is added (equivalent pig iron is used for replacing) as a control group 1; the condition that no piston scrap iron (replaced by equivalent pig iron) and antimony are added is taken as a control group 2 (the spectrum detection composition is composed of C3.4%, si 2.4%, mn0.65%, P < 0.12%, S < 0.15%, cr 0.035%, ni 0.004%, and the rest is Fe); the control group 3 was prepared with a decrease in Sb content of 0.025% (the rest being the same). The gray cast iron materials obtained in this example and the control were subjected to performance test, and the results are shown in Table 1 below.
TABLE 1
| Composition of the components | Brinell hardness/HB | Tensile strength/MPa | Workability/piece/blade |
| Example 1 | 192 | 268 | 142 |
| Control group 1 | 184 | 256 | 100 |
| Control group 2 | 163 | 209 | 66 |
| Control group 3 | 176 | 235 | 117 |
As can be seen from the results in Table 1, the addition of antimony significantly improves the hardness, tensile strength and workability of the gray cast iron material, and can replace the existing expensive reinforcing elements such as tin, copper and the like. By further adding a certain amount of surplus piston scrap iron, the processing performance can be further and obviously improved, and the mechanical performance of the product is not adversely affected. As can be seen from the comparison of the control group 3 with the example 1, when the Sb content is reduced to 0.025%, the hardness and tensile strength of the gray cast iron material obtained are obviously reduced, and the workability is also obviously reduced.
The metallographic structure of the gray cast iron materials obtained in this example and the control group was examined, and the results are shown in Table 2 below.
TABLE 2
| Composition of the components | Graphite morphology | Graphite length/grade | Pearlite% | Ferrite% | Carbide% | Phosphor co-crystal% |
| Example 1 | A type | 4～5 | 98 | 1 | ＜1 | ＜0.5 |
| Control group 1 | A type | 3～4 | 95 | 3 | ＜1 | ＜0.5 |
| Control group 2 | A type | 3～4 | 93 | 5 | 1 | 1 |
| Control group 3 | A type | 4～5 | 97 | 2 | ＜1 | ＜0.5 |
As can be seen from the results in Table 2, the addition of antimony and piston iron filings can increase the pearlite content of the gray cast iron material to a certain extent, and the piston iron filings further increase the graphite length grade in the material, which shows that the above components have the function of refining cast iron graphite and also have the functions of promoting, stabilizing and refining pearlite of cast iron matrix tissues.
Example 2
The method for preparing high-performance gray cast iron (flange (support, bearing and disc cylinder)) by adding piston scrap iron in the embodiment comprises the following preparation steps:
(1) Pouring scrap steel, cast pig iron, piston scrap iron, ferrosilicon, ferromanganese and carburant into an electric furnace for smelting, adding antimony for smelting after more than three slag forming processes, and fully diffusing the antimony; the spectrum detection control is formed into groups: 3.35% of C, 1.8% of Si, 0.75% of Mn, less than 0.12% of P, less than 0.15% of S, 0.03% of Sb, 0.1% of Cr, 0.03% of Ni, 0.02% of Mo and the balance of Fe.
(2) Adding 75 ferrosilicon inoculant accounting for 0.15% of the molten iron mass into the ladle in the step (1) for ladle inoculation treatment for 10min; the spectrum detection control is formed into groups: 3.35% of C, 2.3% of Si, 0.75% of Mn, less than 0.12% of P, less than 0.15% of S, 0.03% of Sb, 0.1% of Cr, 0.03% of Ni, 0.02% of Mo and the balance of Fe.
(3) Tapping the molten iron at the temperature of more than 1490 ℃, transferring to a casting table for casting, and controlling the initial casting temperature to 1420+/-5 ℃ to obtain the high-performance gray cast iron material.
Taking the condition that no piston scrap iron is added (equivalent pig iron is used for replacing) as a control group 4; the comparison group 5 (spectrum detection composition: C3.35%, si 2.3%, mn 0.75%, P < 0.12%, S < 0.15%, cr 0.035%, ni 0.004%, mo 0.001%, and the balance Fe) was prepared by using the case where no piston iron filings (equivalent pig iron was used instead of antimony) and no piston iron filings were added; the control group 6 was prepared with a decrease in Sb content of 0.025% (the rest being the same). The gray cast iron materials obtained in this example and the control were subjected to performance test, and the results are shown in Table 3 below.
TABLE 3 Table 3
| Composition of the components | Brinell hardness/HB | Tensile strength/MPa | Workability/piece/blade |
| Example 2 | 207 | 272 | 133 |
| Control group 4 | 187 | 261 | 91 |
| Control group 5 | 182 | 213 | 54 |
| Control group 6 | 185 | 230 | 106 |
As can be seen from the results in Table 3, the addition of antimony in the composition ratio of this example significantly improves both the tensile strength and the workability of the resulting gray cast iron material, and can replace the existing expensive reinforcing elements such as tin, copper, etc. The processing performance and mechanical property can be further improved obviously by further adding a certain amount of surplus piston scrap iron. As can be seen from the comparison of the control group 6 with example 2, the tensile strength of the gray cast iron material obtained is significantly reduced and the workability is significantly reduced when the Sb content is reduced to 0.025%.
The metallographic structure of the gray cast iron materials obtained in this example and the control group was examined, and the results are shown in Table 4 below.
TABLE 4 Table 4
| Composition of the components | Graphite morphology | Graphite length/grade | Pearlite% | Ferrite% | Carbide% | Phosphor co-crystal% |
| Example 2 | A type | 4～5 | 98 | 1 | ＜1 | ＜0.5 |
| Control group 4 | A type | 3～4 | 95 | 3 | ＜1 | ＜0.5 |
| Control group 5 | A type | 3～4 | 93 | 2 | 1 | 1 |
| Control group 6 | A type | 4～5 | 97 | 2 | ＜1 | ＜0.5 |
As can be seen from the results in Table 4, the addition of antimony and piston iron filings can increase the pearlite content of the gray cast iron material to a certain extent, and the piston iron filings further increase the graphite length grade in the material, which shows that the above components have the function of refining cast iron graphite and also have the functions of promoting, stabilizing and refining pearlite of cast iron matrix tissues.
Example 3
The method for preparing high-performance gray cast iron (air cylinders) by adding piston scrap iron in the embodiment comprises the following preparation steps:
(1) Pouring scrap steel, cast pig iron, piston scrap iron, ferrosilicon, ferromanganese and carburant into an electric furnace for smelting, adding antimony for smelting after more than three slag forming processes, and fully diffusing the antimony; the spectrum detection control is formed into groups: 3.25% of C, 1.75% of Si, 0.85% of Mn, less than 0.12% of P, less than 0.15% of S, 0.035% of Sb, 0.133% of Cr, 0.038% of Ni, 0.028% of Mo and the balance of Fe.
(2) Injecting 75 ferrosilicon inoculant accounting for 0.3% of the molten iron mass into the molten iron ladle in the step (1) for ladle inversion inoculation treatment for 10min; the spectrum detection control is formed into groups: 3.25% of C, 2.2% of Si, 0.85% of Mn, less than 0.12% of P, less than 0.15% of S, 0.035% of Sb, 0.133% of Cr, 0.038% of Ni, 0.028% of Mo and the balance of Fe.
(3) Tapping the molten iron at the temperature of more than 1490 ℃, transferring to a casting table for casting, and controlling the initial casting temperature to 1410+/-5 ℃ to obtain the high-performance gray cast iron material.
Taking the condition that no piston scrap iron is added (equivalent pig iron is used for replacement) as a control group 7; the comparative group 8 (spectral detection composition: C3.25%, si 2.2%, mn 0.85%, P < 0.12%, S < 0.15%, cr 0.035%, ni 0.004%, mo 0.001%, and the balance Fe) was prepared without adding piston iron filings (equivalent pig iron substitution); as a control group 9, the case where the Sb content was increased to 0.040% (the rest was the same). The gray cast iron materials obtained in this example and the control were subjected to performance test, and the results are shown in Table 5 below.
TABLE 5
| Composition of the components | Brinell hardness/HB | Tensile strength/MPa | Workability/piece/blade |
| Example 3 | 214 | 274 | 120 |
| Control group 7 | 186 | 264 | 82 |
| Control group 8 | 207 | 252 | 43 |
| Control group 9 | 215 | 272 | 95 |
As can be seen from the results in Table 5, the addition of antimony in the composition ratio of this example significantly improves both the tensile strength and the workability of the resulting gray cast iron material, and can replace the existing expensive reinforcing elements such as tin, copper, etc. The processing performance and mechanical property can be further improved obviously by further adding a certain amount of surplus piston scrap iron. As can be seen from the comparison of the control group 9 with example 3, when the Sb content was increased to 0.040%, the enhancement of the hardness and tensile strength of the gray cast iron material was not further improved, but the workability was significantly adversely affected.
The metallographic structure of the gray cast iron materials obtained in this example and the control group was examined, and the results are shown in Table 6 below.
TABLE 6
| Composition of the components | Graphite morphology | Graphite length/grade | Pearlite% | Ferrite% | Carbide% | Phosphor co-crystal% |
| Example 3 | A type | 4～5 | ＞98 | ＜1 | ＜1 | ＜0.5 |
| Control group 7 | A type | 3～4 | 95 | 3 | ＜1 | ＜0.5 |
| Control group 8 | A type | 3～4 | 93 | 2 | 1 | 1 |
| Control group 9 | A type | 3～4 | 97 | 1 | ＜1 | ＜0.5 |
As can be seen from the results in Table 6, the addition of antimony and piston iron filings can increase the pearlite content of the gray cast iron material to a certain extent, and the piston iron filings further increase the graphite length grade in the material, which shows that the above components have the function of refining cast iron graphite and also have the functions of promoting, stabilizing and refining pearlite of cast iron matrix tissues.
Comparative example 1
Compared with the example 3, the comparative example has the components of C3.1 percent of the original cylinder type, mn 0.90 percent of the original cylinder type and the original 1385+/-5 ℃ of the initial casting temperature. The preparation method comprises the following specific steps:
(1) Pouring scrap steel, cast pig iron, piston scrap iron, ferrosilicon, ferromanganese and carburant into an electric furnace for smelting, adding antimony for smelting after more than three slag forming processes, and fully diffusing the antimony; the spectrum detection control is formed into groups: 3.1% of C, 1.75% of Si, 0.90% of Mn, less than 0.12% of P, less than 0.15% of S, 0.035% of Sb, 0.133% of Cr, 0.038% of Ni, 0.028% of Mo and the balance of Fe.
(2) Injecting 75 ferrosilicon inoculant accounting for 0.15% of the molten iron mass into the molten iron ladle in the step (1) for ladle inversion inoculation treatment for 10min; the spectrum detection control is formed into groups: 3.1% of C, 2.2% of Si, 0.90% of Mn, less than 0.12% of P, less than 0.15% of S, 0.035% of Sb, 0.133% of Cr, 0.038% of Ni, 0.028% of Mo and the balance of Fe.
(3) Tapping the molten iron at the temperature of more than 1490 ℃, transferring to a casting table for casting, and controlling the initial casting temperature to 1385+/-5 ℃ to obtain the high-performance gray cast iron material.
The results of measuring the properties of the gray cast iron material obtained in this comparative example are shown in Table 7 below.
TABLE 7
| Composition of the components | Brinell hardness/HB | Tensile strength/MPa | Workability/piece/blade |
| Comparative example 1 | 172 | 225 | 94 |
As shown in the results of Table 7, the mechanical properties of the material are reduced by adopting the molten iron component with the original carbon content due to the addition of the piston scrap iron, and the carbon content is improved from 3.1 to 3.2 percent to 3.25 to 3.45 percent and the original Mn content is reduced from 0.85 to 0.95 percent to 0.65 to 0.85 percent by optimizing the content of the molten iron component; meanwhile, from the viewpoints of balancing and optimizing the time, supercooling degree and shrinkage of the molten iron in the condensation process in the cavity after pouring, the original initial pouring temperature is adjusted from the original 1380-1400 ℃ to 1405-1425 ℃, so that the technical effects of improving the processability and the mechanical property at the same time can be achieved.
The main technical indexes achieved by the technical scheme of the invention are as follows:
(1) Balance and digest the piston scrap iron which is surplus in the production of companies every month, reduce the occupied space of the piston scrap iron, avoid the pollution which can be produced during the storage period, shorten the recycling time of material resources and accelerate the utilization efficiency of the circular economy.
(2) The stability of the quality of the casting material in the production process is enhanced, the casting production process is more convenient and easy to control, and the metallographic structure and the hardness of the casting product are stable and accord with high standards.
(3) Further improves the strength, wear resistance and compactness of the casting material, and ensures that the air tightness of cast iron parts is better and the service life is longer.
(4) The processing performance of the casting is further improved, the average service life of the cutter is prolonged from 80-100 pieces/edge to 120-140 pieces/edge, and complaints of the problems of customers are basically eliminated.
The main economic indexes achieved by the technical scheme of the invention are as follows:
(1) Shortens the fund occupation time of the spare piston scrap iron material resources and improves the fund utilization rate.
(2) The alloy piston scrap iron material resource with the common scrap iron value (about 1/2 pig iron value) is effectively utilized. The production of 1000 furnaces of compressor gray cast iron parts per month was approximated by producing 0.2 ton (smelting yield converted to 0.2 x 0.8=0.16 ton at 80%) of piston scrap iron per furnace at a q10# pig iron price of 3100 yuan/ton and a scrap iron market price of 1600 yuan/ton on average. By implementing the project of the invention, the surplus piston scrap iron per month can create income on the gap: 1000×0.16x1500=240000 yuan, about 280 ten thousand yuan can be created in one year, and the economic benefit is considerable.
(3) By implementing the project of the invention, the processing performance and the service performance of the casting are improved, the complaints of related problems can be reduced, the good reputation can be obtained, and the value of the stealth can be increased.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.
Claims (8)
1. A method for preparing high-performance gray cast iron by adding piston scrap iron is characterized by comprising the following preparation steps:
(1) Pouring scrap steel, cast pig iron, piston scrap iron, ferrosilicon, ferromanganese and carburant into an electric furnace for smelting, adding antimony for smelting after more than three slag forming processes, and fully diffusing the antimony; the spectrum detection control is formed into groups: 3.25 to 3.45 percent of C, 1.75 to 1.90 percent of Si, 0.65 to 0.85 percent of Mn, less than 0.12 percent of P, less than 0.15 percent of S, 0.030 to 0.035 percent of Sb, 0.08 to 0.133 percent of Cr, 0.013 to 0.038 percent of Ni, 0.008 to 0.028 percent of Mo and the balance of Fe; the piston scrap iron is scrap iron generated by cutting during machining of the piston, and the chemical composition of the piston scrap iron comprises the following components: 0.65 to 0.85 percent of Cr, 0.15 to 0.45 percent of Ni and 0.1 to 0.4 percent of Mo;
(2) Adding a ferrosilicon inoculant into molten iron in the step (1) for inoculation; the spectrum detection control is formed into groups: 3.25 to 3.45 percent of C, 2.20 to 2.40 percent of Si, 0.65 to 0.85 percent of Mn, less than 0.12 percent of P, less than 0.15 percent of S, 0.030 to 0.035 percent of Sb, 0.08 to 0.133 percent of Cr, 0.013 to 0.038 percent of Ni, 0.008 to 0.028 percent of Mo and the balance of Fe;
(3) And tapping the molten iron at the temperature of more than 1490 ℃, transferring to a casting table for casting, and controlling the initial casting temperature to 1405-1425 ℃ to obtain the high-performance gray cast iron material.
2. The method for preparing high-performance gray cast iron by adding piston scrap iron according to claim 1, wherein the mass percentage of the piston scrap iron in the step (1) is 3-20%.
3. The method for producing high performance gray cast iron with added piston iron filings according to claim 1, wherein the inoculation in step (2) is at least one of ladle inoculation, ladle to ladle inoculation and stream inoculation.
4. The method for preparing high-performance gray cast iron by adding piston scrap iron according to claim 3, wherein the adding amount of ladle inoculation is 0.15% of the mass of molten iron, the adding amount of ladle inoculation is 0.3% of the mass of molten iron, and the adding amount of stream inoculation is 3g/s.
5. A high performance gray cast iron prepared by the method of any one of claims 1 to 4; the high-performance gray cast iron comprises the following components: 3.25 to 3.45 percent of C, 2.20 to 2.40 percent of Si, 0.65 to 0.85 percent of Mn, less than 0.12 percent of P, less than 0.15 percent of S, 0.030 to 0.035 percent of Sb, 0.08 to 0.133 percent of Cr, 0.013 to 0.038 percent of Ni, 0.008 to 0.028 percent of Mo and the balance of Fe.
6. The high-performance gray cast iron according to claim 5, wherein the high-performance gray cast iron has a graphite form of A type, a graphite length of 4-5 grades, a pearlite content of not less than 98%, a ferrite content of less than 2%, carbide of less than 1%, a phosphorus eutectic of less than 0.5%, a hardness HB in a range of 163-255, and a tensile strength of not less than 250Mpa.
7. Use of a high performance gray cast iron according to claim 5 or 6 for the manufacture of an air conditioner compressor casting part.
8. The use of claim 7, wherein the air conditioner compressor casting parts comprise a main bearing, a secondary bearing, a cylinder, and a piston.
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