CN110295312B - Low-temperature nodular cast iron and production process and application thereof - Google Patents
Low-temperature nodular cast iron and production process and application thereof Download PDFInfo
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C33/00—Making ferrous alloys
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- C22C33/10—Making cast-iron alloys including procedures for adding magnesium
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C37/00—Cast-iron alloys
- C22C37/04—Cast-iron alloys containing spheroidal graphite
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- C22C37/00—Cast-iron alloys
- C22C37/10—Cast-iron alloys containing aluminium or silicon
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Abstract
The invention discloses low-temperature nodular cast iron and a production process and application thereof, wherein the nodular cast iron comprises the following elements in percentage by mass: 3.6 to 3.75 percent of C, 1.9 to 2.1 percent of Si, 0.1 to 0.2 percent of Mn, 0.03 to 0.05 percent of Mg, 0.4 to 0.6 percent of Ni, less than or equal to 0.02 percent of P, less than or equal to 0.01 percent of S, less than or equal to 0.02 percent of Ti, and the balance of Fe. The production process comprises the following steps: a. mixing and smelting pig iron, scrap steel, foundry returns, carburant, silicon carbide and silicon at the smelting temperature of 1500-; b. adding a primary inoculant, a nodulizer and a covering agent into the bag, tamping, and then pouring iron liquid into the bag; removing slag; pouring the mixture into a ladle for secondary inoculation, and adding a secondary inoculant; removing slag; casting to obtain casting, and adding inoculant for three times along with flow during casting. The low-temperature nodular cast iron still has excellent low-temperature performance at the temperature of-40 ℃, and is suitable for high-speed rail locomotive parts.
Description
Technical Field
The invention relates to the technical field of nodular cast iron, in particular to low-temperature nodular cast iron and a production process and application thereof.
Background
The nodular cast iron has excellent mechanical property, processing property, wear resistance and shock absorption property and low manufacturing cost, is developed into a cast iron material second to gray cast iron, is widely used, and continuously replaces a cast steel material to manufacture high-requirement structural parts.
The low temperature resistance of common nodular cast iron is not enough, the nodular cast iron gradually changes from toughness to brittleness along with the reduction of the use temperature of a casting, particularly, the impact value is sharply reduced below the brittleness transition temperature, the use requirements under low temperature and high strength cannot be met, and the common nodular cast iron is greatly restricted in the aspect of being applied to workpieces bearing dynamic load at low temperature, so that the further development of the low-temperature nodular cast iron is particularly important.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide the following steps: the low-temperature nodular cast iron still has excellent low-temperature performance at-40 ℃.
The low-temperature nodular cast iron comprises the following elements in percentage by mass: 3.6 to 3.75 percent of C, 1.9 to 2.1 percent of Si, 0.1 to 0.2 percent of Mn0.03 to 0.05 percent of Mg, 0.4 to 0.6 percent of Ni, less than or equal to 0.02 percent of P, less than or equal to 0.01 percent of S, less than or equal to 0.02 percent of Ti, and the balance of Fe.
By adopting the scheme, C is an element formed by strengthening graphite, and carbon and silicon have great influence on the performance of the casting. Moreover, the self-feeding function of graphitization expansion can be fully utilized.
Si is an important element for controlling graphitization and ferrite quantity in the nodular cast iron, and the low-temperature impact toughness of the nodular cast iron is reduced while a ferrite matrix is strengthened. In the experimental process, the low-temperature nodular cast iron has the advantage that the brittle transition temperature is increased from-56 ℃ to-20 ℃ when the mass percentage of Si in the nodular cast iron is increased from 2.35% to 2.8%. When the mass percentage of Si in the nodular cast iron is more than 3.2 percent, the low-temperature brittle transition temperature of the nodular cast iron is higher than room temperature, and the fracture toughness of the nodular cast iron is obviously reduced. Therefore, for the low-temperature nodular cast iron, the mass percentage of Si is strictly controlled to be 1.8-2.3% so as to obtain the high-performance low-temperature nodular cast iron.
Mn is stable and can refine pearlite, improve strength and hardness, but reduce plasticity and toughness and obviously improve brittle transition temperature. In the experimental process, the low-temperature nodular cast iron disclosed by the invention is found that the mass percentage of manganese is increased by 0.1%, and the brittle transition temperature of ferrite nodular cast iron is increased by 10-12%, so that the mass percentage of Mn is controlled to be 0.03-0.05%, and the low-temperature nodular cast iron with high performance is also favorably obtained. Mg can ensure the spheroidization rate, but the residual content is high so as to easily influence the impact property. Ni can strengthen the ferrite matrix and improve the yield strength.
P is a harmful element and is easy to segregate at the eutectic cell boundary to generate phosphorus eutectic, so that the low-temperature toughness of the nodular cast iron is strongly reduced. When the mass percentage of phosphorus is increased by 0.01 percent, the brittle transition temperature is increased by 4 to 4.5 ℃, the impact toughness of the nodular cast iron at minus 40 ℃ is reduced by more than 50 percent when the mass percentage of phosphorus is increased from 0.08 percent to 0.1 to 0.12 percent, and the cold cracking is easy to generate when the mass percentage of P is more than 0.2 percent. The low-temperature nodular cast iron is comprehensively considered, and the mass percentage of P is controlled to be less than or equal to 0.02 percent. Similarly, Ti has the adverse effects of increasing the brittleness of the casting and reducing the strength. The content of P and Ti is controlled, which is beneficial to improving the performance of the casting.
S is an extremely harmful element in the nodular cast iron, and the key for stabilizing the nodularity of the nodular cast iron and improving the nodularity quality of the casting is to control the mass percentage content of S. Generally, the lower the mass percentage of S, the better. The low-temperature nodular cast iron is comprehensively considered, and the mass percentage of S in the nodular cast iron is controlled to be less than or equal to 0.02 percent.
The as-cast structure of spheroidal graphite cast iron is generally a mixed structure of ferrite and pearlite, but the pearlite structure is high in strength and poor in plasticity and toughness, so that the pearlite structure is eliminated as much as possible in low-temperature spheroidal graphite cast iron. The chemical components are decisive factors influencing the performance of the nodular cast iron, determine the solid solution amount of alloy elements in an as-cast structure and ferrite of the nodular cast iron, and different mechanical properties of the nodular cast iron are determined by different matrix structures and the solid solubility of the matrix structures. According to the invention, by limiting the mass percentages of five elements of C, Si, Mn, Mg and Ni and limiting the mass percentages of harmful elements, the pearlite structure in the nodular cast iron is effectively eliminated, the solid solution amount of alloy elements in the matrix structure and ferrite of the nodular cast iron is improved, and the low-temperature nodular cast iron suitable for being applied in alpine regions is obtained.
Moreover, in order to eliminate the pearlite structure in spheroidal graphite cast iron, conventional spheroidal graphite cast iron generally requires a high-temperature annealing heat treatment after casting is completed to minimize the presence of pearlite. In the invention, as the chemical composition control is scientific and reasonable, the pearlite structure in the nodular cast iron is effectively eliminated, so that high-temperature heat treatment is not needed after the pouring is finished, the energy consumption is greatly saved, and the cost is reduced.
The second purpose of the invention is that: the production process of the low-temperature nodular cast iron comprises the following steps:
a. smelting raw materials:
mixing and smelting pig iron, scrap steel, foundry returns, carburant, silicon carbide and silicon at the smelting temperature of 1500-;
b. spheroidizing and inoculating:
b1, spheroidizing and primary inoculation: adding a primary inoculant, a nodulizer and a covering agent into the bag, tamping, and then pouring iron liquid into the bag;
b2, removing slag;
b3, ladle pouring and secondary inoculation, and adding a secondary inoculant;
b4, removing slag;
b5, casting, and adding a tertiary inoculant along with the flow during casting.
The invention is further configured to: and (b) the mass percentage content increase of Si and Mg in the molten iron obtained in the step b1 is as follows: 0.65-0.7% of Si and 0.035-0.045% of Mg; the mass percentage content increase of Si in the molten iron obtained in the step b3 is 0.2-0.25%; and b5, wherein the mass percentage content increase of Si in the molten iron obtained in the step b is 0.06-0.07%.
The invention is further configured to: in step b1, the nodulizer has a particle size of 5-30 mm.
The invention is further configured to: in step b1, the particle size of the primary inoculant is 3-8 mm.
The invention is further configured to: in step b3, the particle size of the secondary inoculant is 3-8 mm.
The invention is further configured to: in step b5, the particle size of the tertiary inoculant is 0.2-0.8 mm.
By adopting the scheme, the preparation method of the low-temperature nodular cast iron adopts three times of inoculation treatment, and strictly controls the increment of two chemical components of Si and Mg in the molten iron during each inoculation treatment, so that the content of the two chemical components of Si and Mg in the final molten iron reaches the limit of the nodular cast iron material.
For the increase in Si content: the primary increment is 0.65-0.7%; the secondary increment needs to be reduced to about one third of the primary increment, specifically 0.2-0.25%; the three increments need to be sharply reduced to about one tenth of the one increment, specifically 0.06-0.07%. For the increment of the Mg content, only one increment is designed, and the increment of Si is matched and is less than one tenth of the increment of Si, specifically 0.035-0.045%.
Three times of inoculation treatment is adopted, and the increment of two chemical components of Si and Mg is strictly controlled, so that the effect is as follows: the nodularity of the nodular cast iron material is obviously improved, the nodularity of the nodular cast iron is as high as 90 percent, and the number of the balls in the nodular cast iron is as high as 200 balls/mm2The elongation of the nodular cast iron is greatly improved, the structure in the nodular cast iron is improved, and the obtained nodular cast iron still has excellent mechanical properties at the temperature of minus 20 ℃.
The invention is further configured to: in the step a, the weight ratio of the pig iron to the scrap steel to the foundry returns is 10-20:50-70: 20-30.
By adopting the scheme, the nodular cast iron adopts a large amount of scrap steel as raw materials, the trace elements in the scrap steel are more, the product quality is not easy to control, and if the imported raw materials are adopted, although the trace elements are less, the cost is higher. The invention strictly controls the chemical components, the tertiary inoculation and the parameter control in each preparation process, so that the obtained nodular cast iron has high quality, the preparation process is easy to control, and the finished product ratio is high. Therefore, the method still improves the quality of the nodular cast iron and the controllability of the preparation process under the condition of adopting a large amount of scrap steel, and has important practical value.
The third purpose of the invention is that: provides an application of the low-temperature nodular cast iron for high-speed rail locomotive parts.
By adopting the scheme, the rapid development of the high-speed rail puts higher requirements on manufacturing parts and parts of the high-speed rail, and the place where the high-speed rail passes often comprises a high-cold field, so that a casting for processing the parts and parts of the high-speed rail is required to have high strength and toughness under a low-temperature condition, brittle fracture is avoided when the high-speed rail runs under a low-temperature environment, long-term safe running can be ensured, and no maintenance or few maintenance is performed. Experiments prove that the strength, the elongation force and the impact toughness of the low-temperature ball casting can reach the European DIN EN1563 standard at the temperature of-40 ℃.
In conclusion, the invention has the following beneficial effects:
1. the prepared low-temperature nodular cast iron effectively eliminates pearlite structures, and the tensile strength can reach 416N/mm2The yield strength can reach 265N/mm2The elongation can reach 20.5 percent, the impact value can reach 14.5J when the ambient temperature is minus 40 ℃, and the low-temperature performance is good;
2. the invention adopts three times of inoculation treatment, and strictly controls the increment of two chemical components of Si and Mg in molten iron during each inoculation treatment, thereby obviously improving the nodularity of the nodular cast iron material, improving the elongation of the nodular cast iron, improving the structure of the nodular cast iron, and finally obtaining the nodular cast iron with excellent mechanical property at the temperature of minus 40 ℃;
3. compared with imported raw materials, the cost can be reduced by 40% by adopting a large amount of scrap steel;
4. the cast after pouring does not need high-temperature heat treatment, thereby greatly saving energy consumption and reducing cost;
5. the chemical components are reasonably selected, and the parameters of the production process are reasonably set, so that the production process is easy to control, and the yield is high;
6. the nodular cast iron is suitable for processing wind power equipment parts and the like in alpine regions.
Detailed Description
The invention is illustrated in further detail below in the following examples:
the adopted pig iron comprises the following elements in percentage by mass: c4.31%, Si 1.21%, Mn 0.13%, P0.029%, S0.02%; the adopted scrap steel comprises the following elements in percentage by mass: 0.17% of Mn, 0.01% of Si, 0.01% of P, 0.01% of S, 0.01% of Cr, 0.04% of Al and 99.6% of Fe;
the adopted carburant comprises the following elements in percentage by mass: 98.93% of fixed carbon, 0.041% of sulfur, 0.60% of ash and 0.47% of volatile component.
Example 1
The low-temperature nodular cast iron comprises the following elements in percentage by mass: 3.6 percent of C, 2.1 percent of Si, 0.1 percent of Mn, 0.05 percent of Mg, 0.4 percent of Ni, less than or equal to 0.02 percent of P, less than or equal to 0.01 percent of S, less than or equal to 0.02 percent of Ti, and the balance of Fe.
The production process comprises the following steps:
a. smelting raw materials:
mixing and smelting pig iron, scrap steel, foundry returns, a carburant, silicon carbide and silicon at the smelting temperature of 1500 ℃ to obtain molten iron, standing for 1min, and performing slag removal treatment until the temperature of the molten iron is reduced to 1470 ℃; wherein the weight ratio of the pig iron to the scrap steel to the foundry returns is 10:70: 20;
b. spheroidizing and inoculating:
b1, spheroidizing and primary inoculation: adding a primary inoculant with the particle size of 3mm and a nodulizer with the particle size of 5mm, wherein the primary inoculant accounts for 0.25% of the total weight of the molten iron, adding a covering agent, compacting, pouring the molten iron, and controlling the reaction time of nodulizing to be 60 s; the mass percentage content increase of Si and Mg in the molten iron obtained in the step is 0.65 percent of Si and 0.035 percent of Mg;
b2, removing slag;
b3, ladle pouring and secondary inoculation: then adding a secondary inoculant accounting for 0.3 percent of the total weight of the molten iron, wherein the granularity of the secondary inoculant is 3 mm; the mass percentage content increase of Si in the molten iron obtained in the step is 0.25%;
b4, removing slag;
b5, casting to obtain a casting, wherein the temperature of the molten iron is 1380 ℃ during casting, and a tertiary inoculant which is 0.1 percent of the total weight of the molten iron is added along with the flow, and the granularity of the tertiary inoculant is 0.2 mm; the mass percentage content increase of Si in the molten iron obtained in the step is 0.06%.
Example 2
The low-temperature nodular cast iron comprises the following elements in percentage by mass: 3.65 percent of C, 2.0 percent of Si, 0.15 percent of Mn0.04 percent of Mg, 0.5 percent of Ni, less than or equal to 0.02 percent of P, less than or equal to 0.01 percent of S, less than or equal to 0.02 percent of Ti, and the balance of Fe.
The production process comprises the following steps:
a. smelting raw materials:
mixing and smelting pig iron, scrap steel, foundry returns, a carburant, silicon carbide and silicon at the smelting temperature of 1520 ℃ to obtain molten iron, then standing for 1min, and performing slag removal treatment until the temperature of the molten iron is reduced to 1480 ℃; wherein the weight ratio of the pig iron to the scrap steel to the foundry returns is 15:60: 25;
b. spheroidizing and inoculating:
b1, spheroidizing and primary inoculation: adding a primary inoculant with the particle size of 5mm and a nodulizer with the particle size of 20mm into the ladle, wherein the primary inoculant accounts for 0.27% of the total weight of the molten iron, adding a covering agent, compacting, then pouring the molten iron, and controlling the reaction time of nodulizing to 65 s; the mass percentage content increase of Si and Mg in the molten iron obtained in the step is 0.67 percent of Si and 0.04 percent of Mg;
b2, removing slag;
b3, ladle pouring and secondary inoculation: then adding a secondary inoculant accounting for 0.27 percent of the total weight of the molten iron, wherein the granularity of the secondary inoculant is 5 mm; the mass percentage content increase of Si in the molten iron obtained in the step is 0.22%;
b4, removing slag;
5, pouring to obtain a casting, wherein the temperature of molten iron is 1370 ℃ during pouring, and a tertiary inoculant which is 0.12 percent of the total weight of the molten iron is added along with the molten iron, and the granularity of the tertiary inoculant is 0.5 mm; the mass percentage content increase of Si in the molten iron obtained in the step is 0.066%.
Example 3
The low-temperature nodular cast iron comprises the following elements in percentage by mass: 3.75 percent of C, 1.9 percent of Si, 0.2 percent of Mn, 0.03 percent of Mg, 0.6 percent of Ni, less than or equal to 0.02 percent of P, less than or equal to 0.01 percent of S, less than or equal to 0.02 percent of Ti, and the balance of Fe.
The production process comprises the following steps:
a. smelting raw materials:
mixing and smelting pig iron, scrap steel, foundry returns, a carburant, silicon carbide and silicon at the smelting temperature of 1550 ℃ to obtain molten iron, then standing for 1min, and performing deslagging treatment until the temperature of the molten iron is reduced to 1490 ℃; wherein the weight ratio of the pig iron to the scrap steel to the foundry returns is 20:50: 30;
b. spheroidizing and inoculating:
b1, spheroidizing and primary inoculation: adding a primary inoculant with the particle size of 8mm and a nodulizer with the particle size of 30mm, wherein the primary inoculant accounts for 0.3% of the total weight of the molten iron, adding a covering agent, compacting, then pouring the molten iron, and controlling the reaction time of nodulizing at 70 s; the mass percentage content increase of Si and Mg in the molten iron obtained in the step is 0.55 percent of Si and 0.045 percent of Mg;
b2, removing slag;
b3, ladle pouring and secondary inoculation: then adding a secondary inoculant accounting for 0.25 percent of the total weight of the molten iron, wherein the granularity of the secondary inoculant is 8mm, and the mass percentage content increment of Si in the molten iron obtained in the step is 0.2 percent;
b4, removing slag;
5, casting to obtain a casting, wherein the temperature of the molten iron is 1350 ℃ during casting, and a tertiary inoculant which is 0.15 percent of the total weight of the molten iron is added along with the molten iron, and the granularity of the tertiary inoculant is 0.8 mm; the mass percentage content increase of Si in the molten iron obtained in the step is 0.07%.
Example 4
The difference between the low-temperature nodular cast iron and the embodiment 2 is that tertiary inoculation is changed into secondary inoculation, and specifically comprises the following steps: no steps b4, b 5; in the step b3, the increase of the mass percentage content of Si in the obtained molten iron is 0.286%.
Example 5
A low-temperature spheroidal graphite cast iron, which is different from embodiment 2 in that: and (b) the mass percentage content increase of Si and Mg in the molten iron obtained in the step b1 is as follows: 0.6 percent of Si and 0.04 percent of Mg; the mass percentage content increase of Si in the molten iron obtained in the step b3 is 0.32%;
and b5, wherein the mass percentage content increase of Si in the molten iron obtained in the step b is 0.036%.
Example 6
A low-temperature spheroidal graphite cast iron, which is different from embodiment 2 in that: and (b) the mass percentage content increase of Si and Mg in the molten iron obtained in the step b1 is as follows: 0.75% of Si and 0.04% of Mg; the mass percentage content increase of Si in the molten iron obtained in the step b3 is 0.12%;
and b5, wherein the increase of the mass percentage content of Si in the molten iron obtained in the step b is 0.086%.
Example 7
A low-temperature spheroidal graphite cast iron, which is different from embodiment 2 in that: and (b) the mass percentage content increase of Si and Mg in the molten iron obtained in the step b1 is as follows: 0.7 percent of Si and 0.04 percent of Mg; the mass percentage content increase of Si in the molten iron obtained in the step b3 is 0.27%;
the increase of the mass percentage of Si in the molten iron obtained in the step b5 was 0.014%.
Example 8
A low-temperature spheroidal graphite cast iron, which is different from embodiment 2 in that: and (b) the mass percentage content increase of Si and Mg in the molten iron obtained in the step b1 is as follows: 0.6 percent of Si and 0.04 percent of Mg; the mass percentage content increase of Si in the molten iron obtained in the step b3 is 0.3%;
and b5, wherein the mass percentage content increase of Si in the molten iron obtained in the step b is 0.056%.
Performance detection
The metallographic structure of the spheroidal graphite cast irons prepared in examples 1 to 8 was examined, and the proportion of the pearlite structure was recorded, and the results are shown in table 1.
The mechanical properties of the spheroidal graphite cast irons prepared in examples 1 to 8 were measured by means of the "DIN EN 1563" standard, using Y-type (type III) specimens as the test specimens, 10 mm. times.10 mm. times.55 mm as the impact test specimens, V-notch, notch depth 2mm, and the results are shown in Table 2.
TABLE 1 metallographic structure test results for nodular cast iron
TABLE 2 detection results of mechanical properties of nodular cast iron
As can be seen from tables 1 and 1, the metallographic structure and mechanical properties of the nodular cast iron prepared in examples 1 to 8 both satisfy the standard requirements.
As can be seen from table 1, the spheroidization ratios of the spheroidal graphite cast irons prepared in examples 1 to 3 are as high as 90%, the pearlite structure is effectively weakened, and the percentage content of the pearlite structure is far below the standard. As can be seen from Table 2, the tensile strength of the spheroidal graphite cast iron prepared in examples 1 to 3 can reach 416N/mm2The yield strength can reach 265N/mm2The elongation can reach 20.5%, the impact value at the ambient temperature of minus 40 ℃ can reach 14.5J, the elongation is far higher than the standard, and the alloy has good low-temperature performance and is suitable for processing high-speed rail locomotive parts and the like. This is because, on the one hand, the control range of the chemical components of the nodular cast iron of the invention is scientific and reasonable; on the other hand, the preparation process adopts three times of inoculation treatment, and effectively controls the process parameters.
As can be seen from the data of examples 2, 4-8 in tables 1 and 2, the change of the tertiary inoculation into the secondary inoculation or the change of the increment of two chemical components of Si and Mg in the tertiary inoculation has obvious influence on the metallographic structure and the mechanical property of the nodular cast iron material, and has the advantages of reduced nodularity, increased pearlite content and reduced strength and elongation. In contrast, the parameter control of examples 1-3 is more reasonable.
The above-mentioned embodiments are merely illustrative and not restrictive, and those skilled in the art can modify the embodiments without inventive contribution as required after reading this specification, but only fall within the scope of the claims of the present invention.
Claims (7)
1. The low-temperature nodular cast iron is characterized by comprising the following elements in percentage by mass: 3.6 to 3.75 percent of C, 1.9 to 2.1 percent of Si, 0.1 to 0.2 percent of Mn, 0.03 to 0.05 percent of Mg, 0.4 to 0.6 percent of Ni, less than or equal to 0.02 percent of P, less than or equal to 0.01 percent of S, less than or equal to 0.02 percent of Ti, and the balance of Fe;
the production process of the low-temperature nodular cast iron comprises the following steps:
a. smelting raw materials:
mixing and smelting pig iron, scrap steel, foundry returns, carburant, silicon carbide and silicon at the smelting temperature of 1500-;
b. spheroidizing and inoculating, and the mass percentage content increase of Si and Mg in the obtained molten iron is as follows: si 0.65-0.7%, Mg 0.035-0.045%;
b1, spheroidizing and primary inoculation: adding a primary inoculant, a nodulizer and a covering agent into the bag, tamping, and then pouring iron liquid into the bag;
b2, removing slag;
b3, ladle pouring and secondary inoculation, and adding a secondary inoculant to obtain the molten iron with the Si mass percentage increase of 0.2-0.25%;
b4, removing slag;
b5, casting, adding inoculant for three times along with the flow during casting, and obtaining the molten iron with the Si mass percentage increase of 0.06-0.07%.
2. The process for producing low-temperature spheroidal graphite cast iron according to claim 1, characterized in that: in step b1, the nodulizer has a particle size of 5-30 mm.
3. The process for producing low-temperature spheroidal graphite cast iron according to claim 1, characterized in that: in step b1, the particle size of the primary inoculant is 3-8 mm.
4. The process for producing low-temperature spheroidal graphite cast iron according to claim 1, characterized in that: in step b3, the particle size of the secondary inoculant is 3-8 mm.
5. The process for producing low-temperature spheroidal graphite cast iron according to claim 1, characterized in that: in step b5, the particle size of the tertiary inoculant is 0.2-0.8 mm.
6. The process for producing low-temperature spheroidal graphite cast iron according to claim 1, characterized in that: in the step a, the weight ratio of the pig iron to the scrap steel to the foundry returns is 10-20:50-70: 20-30.
7. The use of the low temperature spheroidal graphite cast iron of claim 1, wherein: the method is used for high-speed rail locomotive components.
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| CN110592466A (en) * | 2019-10-23 | 2019-12-20 | 淄博乾能铸造科技股份有限公司 | Production method of as-cast low-temperature ductile iron |
| CN111074145B (en) * | 2019-12-05 | 2021-06-01 | 江苏吉鑫风能科技股份有限公司 | Low-temperature-toughness ultra-thick large-end-face ferritic nodular iron casting and preparation method thereof |
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| US3871868A (en) * | 1971-02-04 | 1975-03-18 | Henri Renaud | Method of preparing a corrosion-resistant and ductile iron alloy with a high aluminum content |
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