Ferrite ductile iron alloy composition and low-temperature treatment technology thereof

Abstract

The invention discloses a ferrite ductile iron alloy composition and a low-temperature treatment technology thereof, and relates to the technical field of ductile iron materials. The ferrite ductile iron alloy composition comprises 3.8 wt%-4.2 wt% of C, 3.8 wt%-4.2 wt% of Si, 0.8 wt%-1.2 wt% of Ca, 0.18 wt%-0.2 wt% of Ba, 2.1 wt%-3.2 wt% of Al, 0.08 wt%-0.12 wt% of Sb, 0.08 wt%-0.12 wt% of Bi and the balance Fe and inevitable impurities, wherein the percent is counted on the basis of the total weight of the composition, and cast iron is provided with a ferrite ductile iron structure. By adoption of the high content C and Si, graphitization is promoted, and the forming rate of a ferritic matrix is increased; and due to the fact that the melting point of C and the melting point of Si are higher than the temperature of molten iron, C and Si enter molten iron mainly in a diffusion dissolving manner, a large number of C microcrystals exist in the molten iron, the microcrystals are eutectoid or are eutectic graphite, a very good nucleation substrate is achieved, and grains are better refined.

Description

technical field [0001] The invention belongs to the technical field of spheroidal grinding cast iron materials, and in particular relates to a ferrite spheroidal grinding cast iron alloy composition and a low-temperature treatment process thereof. Background technique [0002] Ferritic nodular cast iron (ferritic nodular cast iron) is ferritic nodular cast iron (referred to as ductile iron), which has certain strength, good impact toughness and plasticity, and can be obtained by casting or annealing. Metallographic structure The morphology of graphite and the metal matrix structure have a great influence on its toughness. (1) The influence of graphite morphology. Under the condition that the metal matrix structure is qualified, the shape of graphite has a great influence on the elongation and impact value: the flake graphite severely splits the metal matrix, and the stress is concentrated at its sharp corners, so the flake graphite cast iron is brittle and the impact value ...

AI Technical Summary

Problems solved by technology

However, the newly produced castings are more or less brittle and have poor impact resistance. Therefore, it is often necessary to heat treat ductile iron castings to eliminate the stress caused by thermal expansion and contraction inside the casting and reduce mechanical stress. Deformation after processing, reduce surface hardness, improve machining conditions; improve its crystal structure, enhance the formation and stability of spherical carbon crystals