Production method for improving graphite form of spheroidal graphite cast iron

A production method and technology of ductile iron, applied in the direction of casting mold, casting mold composition, casting molding equipment, etc., can solve the problem of large fluctuation of punching method, improvement, technology, equipment reliability, and quality of cored wire. and other problems, to achieve the effect of high reliability and simple processing technology

Active Publication Date: 2020-09-01
GUANGXI YUCHAI MACHINE PARTS MFG CO LTD
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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 graphite form of spheroidal graphite cast iron
  • Production method for improving graphite form of spheroidal graphite cast iron
  • Production method for improving graphite form of spheroidal graphite cast iron

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0048] Example 1: Using the prior art method to produce a single pearlite matrix ductile iron crankshaft

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

[0050] (1) Use Q10 low-sulfur low-titanium pig iron 20%, carbon steel 55%, pearlite type reheating iron 25%; then add 0.18% of the total mass of the main charge of 75 ferrosilicon, 0.35% of 65 high-carbon ferromanganese, 0.4 % Electrolytic copper (low lead, 99.99% purity) and 2.45% graphite recarburizer. The composition of raw molten iron obtained by smelting is as follows: C: 3.85%, Si: 0.78%, Mn: 0.42%, Cu: 0.44%, S: 0.012%, Ti: 0.031%.

[0051] (2) Spheroidizing treatment: add 0.95% of the mass of molten iron with low rare earth 1-6 spheroidizing agent, 0.32% BS-1A inoculant, 0.21% BS-1SB, 0.4% 75 silicon Iron is used as an inoculant.

[0052] (3) The molten iron is tapped in 2 steps. In the first step, 85-90% molten iron is produced, and the tapping speed r...

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 dimension is 600*240*245mm.

[0057] (1) Use Q10 low-sulfur low-titanium pig iron 20%, carbon steel 55%, pearlite type reheating iron 25%; then add 0.18% of the total mass of the main charge of 75 ferrosilicon, 0.35% of 65 high-carbon ferromanganese, 0.4 % Electrolytic copper (low lead, 99.99% purity) and 2.45% graphite recarburizer. The composition of the raw molten iron obtained by smelting is as follows: C: 3.85%, Si: 0.78%, Mn: 0.42%, Cu: 0.44%, S: 0.012%, Ti: 0.031%.

[0058] (2) Spheroidizing treatment: Add 0.95% of the mass of molten iron with low rare earth 1-6 spheroidizing agent, 0.32% BS-1A inoculant and 0.21% BS-1SB, and add 0.1% SiCaMn to deoxidize. As an inoculant, 0.4% of 75 ferrosilicon is used as an inoculant.

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

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 dimension is 800*250*250mm.

[0063] (1) Use Q10 low-sulfur low-titanium pig iron 20%, carbon steel 55%, pearlite type reheating iron 25%; then add 0.18% of the total mass of the main charge of 75 ferrosilicon, 0.35% of 65 high-carbon ferromanganese, 0.4 % Electrolytic copper (low lead, purity 99.99%) and 2.45% graphite 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 0.95% of the mass of molten iron with low rare earth 1-6 spheroidizing agent, 0.32% of BS-1A inoculant, 0.22% of BS-1SB, and 0.1% of SiCaMn in the spheroidizing bag Deoxidizer, 0.4% of 75 ferrosilicon is used as an inoculant.

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

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Abstract

The invention provides a production method for improving graphite form of spheroidal graphite cast iron. The method is characterized in that low-sulfur low-titanium pig iron, carbon steel and foundryreturns are selected as main furnace materials, and 75 ferrosilicon, 65 high-carbon ferromanganese, electrolytic copper and a graphite type carburant are added; and smelting is carried out in an intermediate frequency furnace at a specific frequency, and after a spheroidizing agent, an inoculant and a SiCaMn deoxidizer are added, tapping spheroidizing is carried out, wherein in the spheroidizing process, the tapping position, speed and tapping steps are specially set, and in the pouring process, specific inoculant flow velocity and total amount are selected. According to the method, round graphite, which is 2 grade or above in graphite spheroidizing grade, 93 %-99 % in spheroidizing rate and 7 grade in graphite sphere diameter, of a pearlite matrix and mixed-matrix spheroidal graphite castiron casting can be achieved; and the treatment process of the production method is simple and convenient, high in reliability and low in production cost.

Description

Technical field [0001] The invention belongs to the field of casting technology and is a production method for improving the morphology of nodular cast iron graphite. Background technique [0002] Nodular cast 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 terms of yield strength and density. The manufacturing cost is 30-50% lower than that of steel castings. Has good manufacturability. [0003] However, graphite acts as a "defect" in nodular cast iron materials. The presence of graphite destroys the continuity of the metal matrix and has a significant segmentation effect on the matrix. In failed cast iron parts, the cracks all start from graphite. The graphite of nodular cast iron is round, and the graphite of gray cast iron is flake. The edges of flake graphite are sharp blade-shaped, which can easily develop into crack sources under the influence of stress con...

Claims

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Application Information

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Patent Type & Authority Applications(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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