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Method for controlling large-scale nodular iron cast coagulation tissue

A technology of solidification structure and control method, which is applied in the field of control of solidification structure of large ductile iron castings, and can solve problems such as difficult quality control, coarse grains, and graphite distortion

Inactive Publication Date: 2011-04-06
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, large ductile iron castings have a large hot joint modulus and long solidification time, which is prone to microstructure defects such as coarse grains and graphite distortion, resulting in low mechanical properties, especially low elongation, and it is difficult to meet the use requirements, requiring extremely strict production control It is possible to obtain qualified castings only through advanced technology, and quality control is more difficult

Method used

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  • Method for controlling large-scale nodular iron cast coagulation tissue
  • Method for controlling large-scale nodular iron cast coagulation tissue
  • Method for controlling large-scale nodular iron cast coagulation tissue

Examples

Experimental program
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Effect test

Embodiment 1

[0016] Cast a large ductile iron test piece with a diameter of 600mm and a height of 500mm, and the weight of the test piece is about 1 ton. According to the method of the present invention, use such as figure 1 , figure 2 For the cooling body shown, the radius of curvature is selected as 200mm according to the weight of the casting. During casting, the temperature before the molten iron contacts the cooling body is controlled at 1349.8 degrees Celsius according to the formula (1350-casting tonnage / 5); after it flows through the cooling body with a length of 1000mm and an inclination angle of 30°, its temperature drops to the formula (1300 - Casting tonnage / 5) limited 1299.8 degrees Celsius (the temperature at which molten iron flows out of the cooling body can be controlled by adjusting the water flow in the cooling body), then poured into the mold, and obtained a large ductile iron test block after solidification. After dissection, coagulated tissue analysis was performed...

Embodiment 2

[0018] Casting the large-scale nodular cast iron parts of maximum thermal joint size 500mm, weight 30 tons, according to the method of the present invention, according to casting weight, select radius of curvature to be 300mm, inclination angle 30 °, the cooling body that length is 1000mm. During casting, the temperature before the molten iron contacts the cooling body is controlled at 1344 degrees Celsius according to the formula (1350-casting tons / 5); after flowing through the cooling body, the temperature drops to 1294 degrees Celsius limited by the formula (1300-casting tons / 5), Then pour into the mold, and after solidification, large ductile iron castings are obtained. The nesting material in the center of the hot section is analyzed for solidification structure. The results show that, compared with the large ductile iron castings obtained by pouring directly into the mold at 1294 degrees Celsius without cooling, the nodularization rate is increased from 71% to 79%, and t...

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Abstract

The invention relates to a method for controlling a large-scale nodular iron cast coagulation tissue. The method comprises the following steps of: placing a cooling body manufactured by graphite, gray cast iron and copper on a bracket; controlling nodular iron liquid flow and temperature reduction by adjusting an inclined angle to the horizontal direction and the overflow length and controlling the number of iron liquid crystal nucleuses after treatment, wherein the surface of the cooling body is a semicircular concave surface with the curvature radius of 200 to 500 mm and is coated with fireproof coating, the cooling body is hollow and cooling water can be introduced into the cooling body; allowing the nodular iron liquid subjected to nodulizing inoculation to flow through the cooling body and then enter a casting cavity; and properly reducing the casting temperature of the nodular iron liquid and generating a large number of crystal nucleuses through chilling action of the cooling body so as to refine the large-scale nodular iron cast coagulation tissue and prevent graphite distortion.

Description

technical field [0001] The invention relates to the technical field of manufacturing large castings, in particular to a method for controlling the solidification structure of large ductile iron castings. Background technique [0002] In recent years, the production and application of large ductile iron castings have attracted increasing attention. However, large ductile iron castings have a large hot joint modulus and long solidification time, which is prone to microstructure defects such as coarse grains and graphite distortion, resulting in low mechanical properties, especially low elongation, and it is difficult to meet the use requirements, requiring extremely strict production control It is possible to obtain qualified castings only through advanced technology, and quality control is more difficult. Realizing the effective control of the solidification structure of large ductile iron castings is the key to obtaining qualified castings. [0003] Chinese invention paten...

Claims

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Application Information

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IPC IPC(8): B22D1/00C22C33/08C22C37/04
Inventor 黎振华周荣蒋业华岑启宏周荣锋李祖来
Owner KUNMING UNIV OF SCI & TECH
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