Production method for improving the morphology of ductile iron graphite

A technology of ductile iron and production methods, which is applied in the direction of casting molds, casting mold components, casting molding equipment, etc., can solve problems such as lifting and punching method with large fluctuations, unfavorable casting quality, etc., and achieve simple processing technology and high reliability Effect

Active Publication Date: 2022-03-25
GUANGXI YUCHAI MACHINE PARTS MFG CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] 3. The spheroidization process generally adopts the punching method in China. Although the feeding wire spheroidization can improve the grade of graphite, the technology, equipment reliability, and cored wire quality have not yet reached the point of familiarization and promotion. The punching method is still dominant at present. status
[0008] 4. The process of the flushing method fluctuates greatly, and the molten iron rushing angle, speed, position and particle size of the nodulizer and inoculant will all affect the absorption rate of magnesium, and then affect the roundness of graphite
The industry generally increases the amount of nodulizer added to 1.3-1.5%, but too high added amount of nodulizer will increase the slag inclusion in the molten iron, the reaction of the nodularization process is violent, the waste of molten iron is very large, and it will cause rare earth residues in the molten iron The increase of the content will lead to the casting anti-whitening and the shrinkage tendency of the casting, which is not conducive to the improvement of the quality of the casting

Method used

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  • Production method for improving the morphology of ductile iron graphite
  • Production method for improving the morphology of ductile iron graphite
  • Production method for improving the morphology of ductile iron graphite

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0048] Example 1: Production of a single pearlite matrix ductile iron crankshaft using a prior art method

[0049] The weight of the part is 48Kg, the basic wall thickness is 25mm, and the outline size is 600*240*245mm.

[0050] (1) Use Q10 low-sulfur and low-titanium pig iron 20%, carbon steel 55%, pearlitic return iron 25%; then add 75 ferrosilicon with 0.18% of the total mass of the main charge, 0.35% of 65 high carbon ferromanganese, 0.4 % electrolytic copper (low lead, purity 99.99%) and 2.45% graphite type recarburizer. Smelting to obtain raw molten iron with the following compositions: C: 3.85%, Si: 0.78%, Mn: 0.42%, Cu: 0.44%, S: 0.012%, Ti: 0.031%.

[0051] (2) Spheroidizing treatment: add low rare earth 1-6 spheroidizer, 0.32% BS-1A inoculant, 0.21% BS-1Sb, 0.4% 75 silicon, which accounts for 0.95% of the molten iron mass in the spheroidizing bag Iron as an inoculant.

[0052] (3) The molten iron is tapped in 2 steps, 85-90% molten iron is tapped in the first step...

Embodiment 2

[0055] Example 2: Production of a single pearlite matrix ductile iron crankshaft

[0056] The weight of the part is 48Kg, the basic wall thickness is 25mm, and the outline size is 600*240*245mm.

[0057] (1) Use Q10 low-sulfur and low-titanium pig iron 20%, carbon steel 55%, pearlitic return iron 25%; then add 75 ferrosilicon with 0.18% of the total mass of the main charge, 0.35% of 65 high carbon ferromanganese, 0.4 % electrolytic copper (low lead, purity 99.99%) and 2.45% graphite type recarburizer. Smelting to obtain the following raw molten iron: C: 3.85%, Si: 0.78%, Mn: 0.42%, Cu: 0.44%, S: 0.012%, Ti: 0.031%.

[0058] (2) Spheroidizing treatment: add low rare earth 1-6 spheroidizer accounting for 0.95% of the molten iron mass, 0.32% BS-1A inoculant and 0.21% BS-1Sb, add 0.1% SiCaMn deoxidizer in the spheroidizing bag agent, 0.4% of 75 ferrosilicon is used as an inoculant.

[0059] (3) The molten iron is tapped in 2 steps, 85-90% molten iron is tapped in the first step...

Embodiment 3

[0061] Example 3: Production of a single pearlite matrix ductile iron crankshaft

[0062] The weight of the part is 70Kg, the basic wall thickness is 25mm, and the outline size is 800*250*250mm.

[0063](1) Use Q10 low-sulfur and low-titanium pig iron 20%, carbon steel 55%, pearlitic return iron 25%; then add 75 ferrosilicon with 0.18% of the total mass of the main charge, 0.35% of 65 high carbon ferromanganese, 0.4 % electrolytic copper (low lead, purity 99.99%) and 2.45% graphite type recarburizer, smelted to obtain the following raw iron liquid: C: 3.8-3.9%, Si: 0.7-0.9%, Mn: 0.4-0.5% , Cu: 0.4-0.5%, S≤0.03%, Ti≤0.035%.

[0064] (2) Spheroidizing treatment: add low rare earth 1-6 spheroidizing agent, 0.32% BS-1A inoculant, 0.22% BS-1Sb, 0.1% SiCaMn, accounting for 0.95% of the mass of the molten iron in the spheroidizing bag Deoxidizer, 0.4% 75 ferrosilicon as a primary inoculant.

[0065] (3) The molten iron is tapped in 2 steps, 85-90% molten iron is tapped for the fir...

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Abstract

The production method for improving the morphology of ductile iron graphite provided by the present invention, selects low-sulfur and low-titanium pig iron, carbon steel and returned iron as the main charge, and adds 75% ferrosilicon, 65% high-carbon ferromanganese, electrolytic copper and graphite recarburizer; After smelting at a specific frequency in an intermediate frequency furnace, adding nodulizers, inoculants, and SiCaMn deoxidizers, the iron is spheroidized. The nodularization process requires specific iron tapping positions, speeds, and iron tapping steps. The specific inoculant flow rate and total amount are selected during the pouring process. , can achieve pearlite matrix, mixed matrix nodular cast iron casting graphite to achieve spheroidization level 2 and above, the spheroidization rate reaches 93-99%, and the graphite spherical diameter is 7-level rounded graphite. The production method has simple processing technology, high reliability and low production cost.

Description

technical field [0001] The invention belongs to the field of casting technology, and relates to a production method for improving the shape of ductile iron graphite. Background technique [0002] Ductile iron is a widely used high-quality engineering material. It has mechanical properties similar to ordinary cast steel materials, and is superior to steel castings in yield strength and density. The manufacturing cost is 30-50% lower than that of steel castings. Has good craftsmanship. [0003] However, graphite acts as a "defect" in ductile iron materials. The existence of graphite destroys the continuity of the metal matrix and has a significant division effect on the matrix. In failed cast iron parts, cracks all start from graphite. The graphite of ductile iron is round, and the graphite of gray cast iron is flake. The edge of flake graphite has a sharp blade shape, which is easily developed into a crack source under the influence of stress concentration, while the graph...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21C1/10C22C33/10C22C37/10C22C37/04B22D1/00B22C9/08
CPCC21C1/105C22C33/10C22C37/10C22C37/04B22D1/00B22C9/082
Inventor 崔炜李胜柱李伟柱吴宝成郭孝江陶前昭
Owner GUANGXI YUCHAI MACHINE PARTS MFG CO LTD
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