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A kind of production method of compacted graphite cast iron with low shrinkage tendency and compacted graphite cast iron

A technology of vermicular graphite cast iron and production method, which is applied in the field of vermicular graphite cast iron, can solve the problems of inaccurate calculation formulas, inability to truly guarantee, and control near the eutectic point, etc., to reduce scrap rate, shrinkage tendency, and fluctuation range Reduced effect

Active Publication Date: 2022-04-15
GUANGXI YUCHAI MASCH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The existing problems of vermicular graphite cast iron are mainly: the carbon equivalent of molten iron is affected by various components and factors, except for C and Si, each element affects the carbon equivalent to a greater or lesser extent, and the products of the interaction of elements also affect the carbon equivalent , so the traditional carbon equivalent calculation formula is not accurate, and the eutectic point also changes, so controlling C, Si and other components cannot really guarantee that it can be controlled near the eutectic point

Method used

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  • A kind of production method of compacted graphite cast iron with low shrinkage tendency and compacted graphite cast iron
  • A kind of production method of compacted graphite cast iron with low shrinkage tendency and compacted graphite cast iron
  • A kind of production method of compacted graphite cast iron with low shrinkage tendency and compacted graphite cast iron

Examples

Experimental program
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Effect test

Embodiment 1

[0035] To produce four-valve four-cylinder cylinder heads whose material grade is RuT350, the process steps are as follows:

[0036] (1) Ingredients: Prepare raw materials containing C, Si, Cu, Mn, Sn, and iron, and add them to the medium frequency induction furnace. The formula is as follows:

[0037]

[0038] The rest is iron and unavoidable impurities.

[0039] (2) Melting of molten iron: use an intermediate frequency induction furnace to melt the raw materials into raw molten iron, the refining temperature is 1480-1510°C, the holding time is 15-25min, and the slag is removed.

[0040] (3) Thermal analysis of the original molten iron: Take the molten iron from the intermediate frequency furnace and use a tellurium-containing sample cup for thermal analysis inspection. The liquidus temperature of the thermal analysis inspection result is required to be between 1143-1155°C.

[0041] (4) Composition adjustment: When the liquidus temperature is not between 1143-1155°C, add ...

Embodiment 2

[0054] To produce four-valve four-cylinder cylinder heads whose material grade is RuT400, the process steps are as follows:

[0055] (1) Ingredients: Prepare raw materials containing C, Si, Cu, Mn, Sn, and iron, and add them to the medium frequency induction furnace. The formula is as follows:

[0056]

[0057] The rest is iron and unavoidable impurities.

[0058] (2) Melting of molten iron: using an intermediate frequency induction furnace to melt the raw materials into raw molten iron, the refining temperature is 1530-1550°C, the holding time is 15-35min, and the slag is removed.

[0059] (3) Thermal analysis of the original molten iron: Take the molten iron from the intermediate frequency furnace for chemical composition testing, and take the molten iron for thermal analysis with a tellurium-containing sample cup. The liquidus temperature of the thermal analysis test result is required to be between 1142-1152°C. And calculate the carbon equivalent.

[0060] (4) Composi...

Embodiment 3

[0071] To produce four-valve four-cylinder cylinder heads whose material grade is RuT450, the process steps are as follows:

[0072] (1) Ingredients: Prepare raw materials containing C, Si, Cu, Mn, Sn, and iron, and add them to the medium frequency induction furnace. The formula is as follows:

[0073]

[0074] The rest is iron and unavoidable impurities.

[0075] (2) Melting of molten iron: using an intermediate frequency induction furnace to melt the raw materials into raw molten iron, the refining temperature is 1500-1530°C, the holding time is 15-35min, and the slag is removed.

[0076] (3) Thermal analysis of the original molten iron: Take the molten iron from the intermediate frequency furnace for chemical composition testing, and take the molten iron for thermal analysis with a tellurium-containing sample cup. The liquidus temperature of the thermal analysis test result is required to be between 1140-1150°C. And calculate the carbon equivalent.

[0077] (4) Composi...

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Abstract

The invention discloses a production method of vermicular graphite cast iron with low shrinkage tendency, which comprises the steps of furnace charge preparation, molten iron smelting, molten iron refining, vermicularization and inoculation treatment, and pouring castings. Composition adjustment and refining, and control the liquidus temperature of molten iron between 1135-1155°C; in the creeping and inoculation treatment, according to the comparison between the liquidus temperature of the current molten iron and the liquidus temperature of the original molten iron, add inoculants and vermicular agent, so that the final molten iron meets the requirements of vermicular index of 12-14, inoculation index of 12-18, and eutectic index of 120-150, so that the carbon equivalent of vermicular graphite cast iron is controlled near the eutectic point, reducing shrinkage Pore ​​tendency, and finally achieve the beneficial effect of reducing the scrap rate.

Description

technical field [0001] The invention relates to compacted graphite cast iron, in particular to a production method of compacted graphite cast iron with low shrinkage tendency. At the same time, the invention relates to the compacted graphite cast iron obtained by the production method. Background technique [0002] Vermicular graphite cast iron is a gray cast iron with a transition form between flake and spheroidal graphite. It is an engineering structural material characterized by good mechanical properties and thermal conductivity and low cross-sectional sensitivity. [0003] The grades of vermicular graphite cast iron from low to high are RuT300, RuT350, RuT400, RuT450, RuT500, etc. With the increase of grades, the casting process performance becomes worse, especially after RuT450, the main problem is the tendency of shrinkage cavity increases , When producing castings with complex structures such as cylinder heads and many hot spots, the shrinkage cavity rejection rate ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C33/08C21C1/08B22D1/00B22D46/00C22C37/10
CPCC22C33/08C21C1/08B22D1/00B22D46/00C22C37/10
Inventor 刘治军杜文科陈宏兴杨任麻林周应荣李南周树政
Owner GUANGXI YUCHAI MASCH CO LTD