Killed steel casting method

A casting method and technology for killing steel, applied in the field of metallurgical casting, can solve the problems of prolonged solidification time of steel ingots, difficult discharge of gas in steel, increase of inclusions, etc. The effect of surface cracks

Inactive Publication Date: 2009-05-27
攀钢集团成都钢铁有限责任公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The conventional killed steel casting technology is used to cast this kind of round wave steel ingot. The casting speed is too high, the casting temperature is too high and the slow cooling time is too short when mold cooling is used, which will make the chilled layer of the steel ingot thinner and the molten steel in the mold will be static. The pressure increases rapidly, it is easy to produce cracks in the middle and lower parts of the steel ingot, and the gas in the steel is not easy to discharge; in addition, the solidification time of the entire steel ingot is prolonged, resulting in aggravated composition segregation, increased inclusions, relatively developed columnar crystals, and increased temperature difference between the inside and outside of the steel ingot. The tendency to generate internal cracks increases; the internal and surface quality requirements of the periodic pipe rolling unit for rolling large-diameter thick-walled seamless pipes cannot be met, and it is difficult to achieve less metal consumption and low cost for the periodic pipe rolling unit , the market competitive advantage of multi-spec and multi-variety production

Method used

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Experimental program
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Effect test

Embodiment 1

[0019] The casting method of killed steel of the present invention, with the steel ingot mold of wave section 2 as shown in Figure 1, adopts down casting method to cast 20 in 90t electric furnace # Φ580 / 4.0t large round corrugated steel ingot for pipe rolling with 25 sides of upper, lower, and lower.

[0020] 1. Process flow of steel ingots for casting and rolling pipes:

[0021] Electric furnace → DC (direct current) - ladle refining furnace LF → mold casting (car casting) → mold cooling → demoulding → steel ingot surface cleaning

[0022] 2. Quality control of molten steel:

[0023] 2.1 Before the end of refining, feed CaSi wire 0.4~0.6kg / t steel, and control the sulfur content of the steel out of the refining furnace below 0.025%;

[0024] 2.2 The temperature of the molten steel leaving the refining furnace is 1560-1580°C;

[0025] 3. Technical requirements for casting heat insulation board, mold slag and carbonized rice husk heat preservation agent:

[0026] 3.1 Techn...

Embodiment 2

[0073] The 90t electric furnace adopts the bottom casting method to cast 20G, Φ500 / 2.5t large round corrugated steel ingots for pipe rolling with upper, lower, and large 23 sides

[0074] 1. Process flow of steel ingots for casting and rolling pipes:

[0075] Electric furnace → DC (direct current) - ladle refining furnace LF → VD (vacuum treatment) → mold casting (vehicle casting) → mold cooling → demoulding → steel ingot surface cleaning

[0076] 2. Liquid steel quality control:

[0077] 2.1 The furnace body is abnormal and the second furnace before the new furnace body cannot smelt Benxi Steel;

[0078] 2.2 New ladles and new ingot molds shall not be used;

[0079] 2.3 The casting system must be clean and dry, and cast with Ar gas protection;

[0080] 2.4 Feed CaSi wire 0.4~0.6kg / t steel before the end of refining, control the sulfur out of the refining furnace below 0.025%, and the temperature of molten steel out of the VD furnace is 1565~1580℃;

example 1

[0082] 4. Preparation before casting:

[0083] 4.1 Select the steel ingot mold with good inner surface quality, do a good job of brushing the mold, and use high-quality refractory materials for the casting system.

[0084] 4.2 It is strictly forbidden to use cold molds and hot molds, and the temperature of the ingot mold during casting should not exceed 60°C;

[0085] 4.3 See Table 2 for the height of the center injection pipe used

[0086] 4.3 Use the ingot mold every time to clean the residual steel and sticky slag on the inner wall, and then blow it with compressed air;

[0087] 4.4 It is forbidden to water the ingot mold for cooling.

[0088] 4.5 See Example 1 for others.

[0089] 5. Casting operation:

[0090] 5.1 Casting superheat: 60~90℃;

[0091] 5.2 Pouring speed: see Table 2

[0092] 5.3 The steel pouring operator should determine the casting speed according to the temperature of molten steel and the season, and the liquid steel level should rise steadily durin...

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Abstract

A periodic tube rolling machine with slant rolling drill rig is used to generate big caliber thick wall steel blocks, to satisfy the inside and surface quality requirements. Inner cavity working section of the mold is wave shape multilateral cross section shape wave ingot mold, with sulfur content controlled under 0.025% of the steel liquid, casting temperature within 40 to 80DEG C, linear speed 80 to 230mm / min, cracking ratio lower than 5%, pass rate 98.81%, with low consumption of metal, low cost, especially suitable for rolling into seamless steel tubes with multi types and specification and phi> / =426mm.

Description

technical field [0001] The invention relates to a metallurgical casting method, in particular to a casting method of killed steel for producing steel ingots for large-diameter thick-walled pipes by using a periodic pipe rolling unit with a cross-rolling piercer. Background technique [0002] At present, the casting of killed steel generally adopts the upper casting method; and the upper casting method has to adopt a higher casting speed in order to prevent the temperature of the last cast steel ingot from being too low; while the lower casting method can cast the steel ingot in a short time It can cast several steel ingots at the same time, and it is more convenient to adjust the injection speed. The casting speed of the upper casting method is generally 600-900mm / min, and the casting speed of the lower casting method is generally 170-350mm / min. The casting temperature is generally expressed by the degree of casting superheat. Generally, the degree of casting superheat is 1...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B22D7/04
Inventor 王乃斌马欢鱼张珉苏雄杰易良刚周军
Owner 攀钢集团成都钢铁有限责任公司
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