Instant inoculation method

Abstract

The invention relates to an instantaneous inoculation method, which has good inoculation effect, improves the quality consistency of forged pieces, and can be used for producing wind power generation forged pieces with extremely high performance requirements and capable of resisting low-temperature shock to large-section ductile iron. The method adopts a runner cup to pour; molten iron is poured into a straight pouring channel at constant flow rate; and the method is characterized in that instantaneous inoculant is added into a sand box from the top of the sand box at a uniform speed at the same time of pouring and then enters the straight pouring channel in the sand box through a pipeline, and the instantaneous inoculant and the molten iron in a half filling state in the straight pouring channel are mixed and then poured into a die cavity.

Description

technical field [0001] The invention relates to an instantaneous inoculation method, in particular to an instantaneous inoculation method for casting wind power generation castings by adopting sprue cup pouring. Background technique [0002] The material of wind power castings is generally EN GJS400-18LT or EN GJS350-22LT, which is ductile iron with large cross-section, high toughness and low temperature impact resistance. The acceptance conditions for its mechanical properties and metallographic structure are extremely strict. In the production process of wind power castings, multiple inoculations are generally adopted: inoculation in the ladle, inoculation in the tap trough, and instantaneous inoculation, among which instantaneous inoculation is the most critical. [0003] At present, the commonly used instantaneous inoculation method is to manually add the instantaneous inoculant into the sprue cup. This method has the following problems: 1. Because the instantaneous ino...

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Problems solved by technology

[0003] At present, the commonly used instantaneous inoculation method is to manually add the instantaneous inoculant into the sprue cup. This method has the following problems: 1. Because the instantaneous inoculant will float on the upper surface of the molten iron in the sprue cup, the instantaneous inoculant cannot be guaranteed. The inoculant effectively enters the mold cavity, and does not have a good instantaneous inoculation effect on the casting; 2. The instantaneous inoculant needs to be completely dissolved in the sprue cup before entering the cavity, causing the inoculation process to lag behind the solidification of the casting. The inoculation effect of each part is uneven, the inoculation effect at the bottom of the casting is poor, and the amount of instantaneous inoculant added to the upper part of the casting is too large, which will deteriorate the performance of the casting due to the easy generation of aggregated graphite

Even though the absorption of the transient inoculant will be homogenized during the solidification process of the casting, due to the complexity of the casting structure, it is difficult to ensure that the transient inoculant is completely and evenly distributed; 3. Manual addition cannot ensure the addition and uniform distribution of the transient inoculant sex, poor fertility

[0004] At present, the commonly used instantaneous inoculants include 75SiFe, Re-Si-Ba-Ca, etc., but for the large-section ductile iron of wind power generation parts, they cannot effectively increase the number of graphite balls, so that the diameter of graphite balls in the casting structure is large, And it is easy to produce graphite distortion or even fragmented graphite, the spheroidization rate is low, and the mechanical properties of the casting cannot be guaranteed

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