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High-quality centrifugal casting method for steel pipe blank

A technology of centrifugal casting and steel tube billet, applied in the field of high-quality centrifugal casting steel tube billet, can solve the problems of uneven material, uneven distribution, difficult control, etc., to reduce inclusion content, high metal yield, and prevent oxygen oxidation Effect

Inactive Publication Date: 2014-06-11
WUHU XINXING DUCTILE IRON PIPES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the disadvantage of this method is that the rotation speed of the cavity is not quantified, it needs to be changed all the time, and it is not easy to control. The influence of element segregation is not considered when selecting the centrifugal acceleration, especially for thick-walled pipes, and element segregation leads to trace elements in the steel. Uneven distribution, some enrichment, some very few, resulting in uneven steel material, which in turn produces defects, affecting its mechanical properties, such as bearing capacity, plastic properties, etc.
In addition, this method is in an open environment in contact with air during the pouring process. During the process of molten steel from the tapping hole to the launder and injected into the cavity through the launder, it is polluted twice by oxidation, which seriously affects the quality of molten steel.

Method used

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  • High-quality centrifugal casting method for steel pipe blank

Examples

Experimental program
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Effect test

Embodiment 1

[0016] Centrifugal casting of high-quality 4140 steel pipe billet for petroleum, its specification is φ550 / 350×2000mm, its centrifugal casting method:

[0017] (1) According to the formula N=20×(G / r) 1 / 2 , first calculate the carbon equivalent Ceq=0.773 of the 4140 petroleum steel pipe billet, according to figure 2 The linear relationship shown: from the figure, Ceq=0.773 corresponds to G to take 57, the radius of the inner surface of the steel pipe billet is taken into consideration of 10mm machining allowance to take 0.165m, and the calculated centrifugal speed is 370r / min;

[0018] (2) Adjust the speed of the centrifuge to 370r / min, pour molten steel from the ladle into the cavity, combine figure 1 As shown, a funnel-shaped tundish 3 is connected between the ladle 1 and the cavity 2, and argon gas is introduced from the ladle 1, and the flow rate of the argon gas is 150 L / min, so that the argon gas enters the tundish 3 and the cavity 2 , the two open ends of the cavity 2...

Embodiment 2

[0021] Centrifugal casting of high-quality 45# steel billet, its specification is φ460 / 350×2000mm, its centrifugal casting method

[0022] (1) According to the formula N=20×(G / r) 1 / 2 , Ceq=0.61, according to figure 2 In the linear relationship diagram shown, G is 60, and the inner surface radius of the steel tube billet is 0.165m considering the 10mm machining allowance, and the calculated centrifugal speed is 380r / min;

[0023] (2) Adjust the speed of the centrifuge to 380r / min, pour molten steel from the ladle into the cavity, combine figure 1 As shown, a funnel-shaped tundish 3 is connected between the ladle 1 and the cavity 2, and argon gas is introduced from the ladle 1, and the flow rate of the argon gas is 120 L / min, so that the argon gas enters the tundish 3 and the cavity 2 , surrounded by the outer layer of molten steel; the two open ends of the cavity 2 are sealed with two baffles 4, so that the tundish 3 is sealed and extends into the inner cavity of the cavity ...

Embodiment 3

[0026] Method for Centrifugal Casting High Quality 65Mn Steel Billet (Specification φ420 / 240×2000)

[0027] (1) Quickly calculate the centrifugal speed.

[0028] According to N=20×(G / r) 1 / 2 . Ceq=0.817, according to figure 2 In the shown relationship, G is 55, the radius of the inner surface of the steel tube billet is 0.110m (considering the machining allowance of 10mm), and the calculated centrifugal speed is 450r / min.

[0029] (2) Using gas protection pouring.

[0030] Adjust the speed of the centrifuge to 450r / min, control the pouring temperature within the range of 1528-1538°C, and the liquidus temperature of the steel is 1508°C. Gas protection casting is adopted, the weight of the centrifugal steel billet is 1.9 tons, and the time control is completed within 4 minutes. Gas protection methods such as figure 1 As shown, one is to use a funnel-shaped tundish. The tundish can protect the stage from the tapping hole to the launder from oxygen pollution. Adding a funnel...

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Abstract

The invention discloses a high-quality centrifugal casting method for a steel pipe blank, belonging to a centrifugal casting process. The high-quality centrifugal casting method comprises the following steps of: calculating centrifugal rotation speed of a cavity according to a formula of N=20*(G / r)1 / 2, wherein N is the centrifugal rotation speed of the cavity, r is internal radius of the steel pipe blank, and G is gravity coefficient of the steel pipe blank and is taken to be 44-77; after rotating the cavity at the calculated centrifugal rotation speed, pouring molten steel into the cavity from a ladle; guaranteeing that the molten steel is sealed and is not oxidized by gas during pouring, wherein the pouring temperature is 20-30 DEG C greater than liquidus temperature of the molten steel, and the pouring time is 3-10 minutes; and demolding after pouring, cooling the centrifugal steel pipe blank to room temperature, measuring contents of sulfur and oxygen included in the steel pipe blank, and removing impurities of an inner surface layer through an inner boring machining method. According to the high-quality centrifugal casting method, quantification of the rotation speed of the cavity can be realized, the machining is convenient, the control is easy and the influence of segregation of elements is extremely low.

Description

technical field [0001] The invention relates to a centrifugal casting process, in particular to a high-quality centrifugal casting steel billet method. Background technique [0002] The mechanical properties of centrifugally cast metal products are closely related to the shape and size of grains, and the products with fine equiaxed grain structure have higher tensile strength, yield strength and creep strength than those with coarse columnar grain structure. products. The traditional pouring method of centrifugal casting is: firstly, manual slag extraction, overturning operation, and then pouring through the movement of the launder. During the pouring process, the cavity is always rotating at a high speed and at a constant speed. For heat-resistant steel, under the usual conditions of centrifugal casting, only a structure with relatively developed columnar grains can be obtained. The root cause of this coarse columnar grain structure is that the liquid metal and the solidif...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B22D13/12B22D13/02
Inventor 彭涛孙韶华张洪彪朱丽丽
Owner WUHU XINXING DUCTILE IRON PIPES
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