Preparation method of as-cast nodular cast iron and nodular cast iron

Abstract

The invention discloses a preparation method of as-cast nodular cast iron and the nodular cast iron. The preparation method comprises the following steps of smelting, adjusting the component content of molten iron, adding alloy elements, nodulizing, microalloying, inoculating and pouring. The method has the advantages that the strength of extension of the nodular cast iron can be stably controlled to be higher than 700MPa, the elongation at break is about 4.5%, the process of normalizing or quenching-tempering heat treatment in the conventional production method can be simplified, and high-temperature normalizing or quenching and tempering can be avoided; compared with nodular cast iron produced by the conventional as-cast production method, the nodular cast iron prepared by the preparation method can achieve both high strength and high plasticity.

Description

technical field [0001] The invention relates to the field of cast iron production, in particular to a preparation method of as-cast nodular cast iron and the nodular cast iron. Background technique [0002] With the wide application of ductile iron in oil drilling, automobile manufacturing and engines, the requirements for the strength and plasticity of ductile iron are getting higher and higher. For example, in oil drilling, high-speed movement improves work efficiency and increases power, resulting in The friction of friction doubles, the heat generated increases, and higher requirements are put forward for the high temperature performance, strength and plasticity of castings. For example, the crosshead of oil drilling requires mechanical properties of tensile strength ≥ 689MPa, yield strength ≥ 483MPa, ≥3.0%, and require the finished surface to have sufficient hardness, so designers generally use high-strength and high-plastic ductile iron materials. [0003] No matter a...

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Problems solved by technology

[0003] No matter at home or abroad, conventional nodular cast iron is generally used for production. After adjusting the composition, it can achieve this performance through normalizing or quenching and tempering heat treatment. Its production cycle is long, the cost is high, and castings are prone to problems such as severe tool wear caused by high hardness during rough machining; while using the as-cast production method, although some production units also improve mechanical properties by adding alloy elements, the mechanical properties The performance is unstable, and one of the indicators in the strength or plasticity is prone to be low and unqualified

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