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Production method for vermicular graphite cast iron with low shrinkage tendency and vermicular graphite cast iron

A technology of vermicular graphite cast iron and production method, which is applied in foundry equipment, safety devices, manufacturing tools, etc., can solve the problems of inaccurate calculation formula, can not really guarantee, control near the eutectic point, etc., so as to reduce the scrap rate and reduce Shrinkage tendency and the effect of reducing the fluctuation range

Active Publication Date: 2021-07-09
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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  • Production method for vermicular graphite cast iron with low shrinkage tendency and vermicular graphite cast iron
  • Production method for vermicular graphite cast iron with low shrinkage tendency and vermicular graphite cast iron
  • Production method for vermicular graphite cast iron with low shrinkage tendency and vermicular graphite cast iron

Examples

Experimental program
Comparison scheme
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 for vermicular graphite cast iron with low shrinkage tendency. The method comprises the steps of furnace burden preparation, molten iron smelting, molten iron refining, vermicularizing and inoculation treatment and casting pouring. In the molten iron refining process, base molten iron obtained through molten iron smelting is subjected to component adjustment and refining, and the liquidus temperature of the molten iron is controlled to be 1135-1155 DEG C; in the vermicularizing and inoculation treatment, an inoculant and a vermiculizer are added according to the comparison result of the liquidus temperature of the current molten iron and the liquidus temperature of base molten iron, so that the final molten iron meets the requirements that the vermicularizing index is 12-14, the inoculation index is 12-18 and the eutectic index is 120-150, the carbon equivalent of the vermicular graphite cast iron is controlled to be close to the eutectic point, the shrinkage tendency is reduced, and the beneficial effect of reducing the rejection rate is finally achieved.

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 Applications(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