Vermicular agent and preparation method thereof

Abstract

The invention relates to a vermicular agent and a preparation method thereof. The vermicular agent is an alloy and comprises the following element components in parts by weight: 9 to 12 parts of La, 7 to 10 parts of Ce, 4 to 6 parts of Mg, 2 to 5 parts of Ca, 36 to 44 parts of Si, and 22 to 42 parts of Fe. The vermicular agent is obtained by smelting raw materials in the proportion of target product components. By using the vermicular agent, the percentage of vermicular graphite is improved, the range of the percentage of vermicular graphite is reduced, moreover, the chilling tendency of produced vermicular iron pieces is low, the slenderness ratio of vermicular graphite is low, and the plastic toughness of the vermicular iron pieces is high.

Description

technical field [0001] The invention relates to a vermicular agent and a preparation method thereof. Background technique [0002] Vermicular graphite cast iron (hereinafter referred to as vermicular iron) is an engineering material that began to be applied in the 1970s, but the development speed in the past 40 years is not as fast as that of ductile iron. One of the important reasons affecting the development of vermicular iron is that the range of creep rate is difficult to control, and the vermicular agent is the direct factor affecting the creep rate. [0003] The vermicular agents developed in the past 40 years generally have the following types: [0004] ①Magnesium-titanium-ferrosilicon series alloys (magnesium-titanium-low rare earth-calcium alloys). This kind of vermicular agent has a small whitening tendency and a wide range of dosage, and is especially suitable for thin-walled vermicular iron parts. However, the titanium in this kind of vermicular agent will acc...

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Problems solved by technology

However, the addition of magnesium increases the amount of nodular graphite in vermicular iron, reduces the creep rate, deteriorates the casting performance, processing performance, and thermal conductivity of castings, and increases the difficulty of producing vermicular iron with high creep rate.

[0007] There are two common shortcomings of the above types of vermicular agents (also two major problems in the production of vermicular iron): a). The range of vermicularization rate is difficult to control. ) may reach 50~70%, and the allowable range should be ≤30%; b). High creep rate is difficult to obtain. Many important creep iron parts such as automobile engine block and cylinder head require creep rate ≥70% or even ≥80%, while the existing vermicular agents can basically only achieve a creep rate of ≥50% or even lower

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