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A wire-feeding and spheroidizing method of investment casting nodular cast iron

A technology of investment precision casting and nodular cast iron, which is applied to casting molding equipment, casting molds, and casting mold components. The effect of stable graphite size and stable residual Mg content

Active Publication Date: 2020-08-21
DONGFENG PRECISION CASTING CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] The shell temperature of investment casting is above 700℃, which will cause the solidification time of molten iron to be much longer than that of sand casting. That is to say, when investment casting produces ductile iron, the eutectic time is much longer than that of sand casting. A longer eutectic time will lead to an increase in the tendency of graphite distortion, an increase in the probability of worm-like graphite, and a decrease in the spheroidization level. Most of them can only reach 2-4 spheroidization levels.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] A method for feeding and spheroidizing ductile iron by investment casting in this embodiment comprises the following steps:

[0037] (1) Shell making and roasting of investment casting mold: use silica sol and quartz powder as the surface coating, the mass ratio of silica sol and quartz powder is 1:1.5, use silica sol and mullite powder as the back coating, silicon The mass ratio of sol to mullite powder is 1:1.5, and the shell is roasted in a through-type natural gas roaster at a roasting temperature of 900-950°C and a roasting time of 2.5 hours;

[0038] (2) Melting of molten iron: Melting molten iron in an intermediate frequency induction furnace. According to the mass percentage, 25% of Q10 pig iron, 30% of returned material and 45% of scrap steel are selected as the furnace charge. The carbon equivalent of molten iron before spheroidizing treatment is 4.15%, and S≤0.02%;

[0039] (3) Spheroidization treatment: Spheroidized molten iron ladle is used. The ladle’s con...

Embodiment 2

[0043] A method for feeding and spheroidizing ductile iron by investment casting in this embodiment comprises the following steps:

[0044] (1) Shell making and roasting of investment casting mold: use silica sol and quartz powder as the surface coating, the mass ratio of silica sol and quartz powder is 1:2, use silica sol and mullite powder as the back coating, silicon The mass ratio of sol to mullite powder is 1:2, and the shell is roasted in a through-type natural gas roaster at a roasting temperature of 900-950°C and a roasting time of 3 hours;

[0045](2) Molten iron smelting: use medium frequency induction furnace to smelt molten iron. According to the mass percentage, 30% of Q10 pig iron, 20% of returned material and 50% of steel scrap are selected as the furnace charge. The carbon equivalent of molten iron before spheroidizing treatment is 4.2%, and S≤0.02%;

[0046] (3) Spheroidization treatment: Spheroidized molten iron ladle is used. The ladle’s containment weight i...

Embodiment 3

[0050] A method for feeding and spheroidizing ductile iron by investment casting in this embodiment comprises the following steps:

[0051] (1) Shell making and roasting of investment casting mold: use silica sol and quartz powder as the surface coating, the mass ratio of silica sol and quartz powder is 1:2.5, use silica sol and mullite powder as the back coating, silicon The mass ratio of sol to mullite powder is 1:2.5, and the shell is roasted in a through-type natural gas roaster at a roasting temperature of 900-950°C and a roasting time of 3.5 hours;

[0052] (2) Molten iron smelting: use medium frequency induction furnace to smelt molten iron. According to the mass percentage, 10% of Q10 pig iron, 30% of returned charge and 60% of steel scrap are selected as the furnace charge. The carbon equivalent of molten iron before spheroidizing treatment is 4.25%, and S≤0.02%;

[0053] (3) Spheroidizing treatment: adopt spheroidized molten iron ladle, the contained weight of the mo...

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Abstract

The invention relates to a wire feeding and spheroidizing method for nodular cast iron in investment precision casting. The wire feeding and spheroidizing method for nodular cast iron in investment precision casting comprises the following steps: investment casting shell making and roasting; molten iron smelting; spheroidizing treatment; inoculation; and mold shell pouring. According to the methoddisclosed by the invention, the problem of low spheroidization grade in production of the nodular cast iron by wire feeding and spheroidizing in investment precision casting is solved, the nodular cast iron can be produced in batches by adopting the method, compared with spheroidization by a punching method, the wire feeding and spheroidizing method has the advantages that the content of residualMg in molten iron is more stable, the content of residual Mg is improved to 0.04-0.06%, the spheroidization grade of the nodular cast iron piece is improved to 1-3, the size of graphite is stable andreaches grade 6-7, and no carbide exists.

Description

technical field [0001] The invention belongs to the technical field of casting, and in particular relates to a wire-feeding and spheroidizing method for investment precision casting nodular cast iron. Background technique [0002] The shell temperature of investment casting is above 700°C, which will cause the solidification time of molten iron to be much longer than that of sand casting. That is to say, when investment casting produces ductile iron, the eutectic time is much longer than that of sand casting. A longer eutectic time will lead to an increase in the tendency of graphite distortion, an increase in the probability of worm-like graphite, and a decrease in the spheroidization level, most of which can only reach 2-4 levels of spheroidization. Therefore, when producing nodular cast iron by investment casting, in order to stably achieve spheroidization level 1-3, the control requirements for the amount of residual Mg in molten iron and inoculation must be higher than ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C33/10C22C37/04C21C1/10B22C9/04
CPCB22C9/04C21C1/105C22C33/10C22C37/04Y02P10/143Y02P10/20
Inventor 陈礼年王永华蓝勇
Owner DONGFENG PRECISION CASTING CO LTD