D-type graphite cast iron and production method thereof

Abstract

The invention discloses D-type graphite cast iron and a production method thereof and belongs to the technical field of graphite cast iron. The D-type graphite cast iron has the characteristics of high tensile strength, high content of pearlite in a matrix and high thermal fatigue resistance. The production method of the D-type graphite cast iron has the advantages of simple process and low cost; the D-type graphite cast iron comprises the following components in percentage by weight: 3.0-3.3 percent of carbon, 1.9-2.3 percent of silicon, 1.5-2.0 percent of manganese, 0.6-1.0 percent of copper, 0.08-0.12 percent of titanium, 0.06-0.08 percent of sulfur, 0.005-0.015 percent of magnesium, 0.005-0.015 percent of rare earth, less than or equal to 0.03 percent of phosphorus and the balance of iron. The production method comprises the following steps: fusing raw materials, blowing argon into liquid iron, discharging, pouring a ladle, carrying out first time of breeding, pouring a casting mold and carrying out second time of breeding. The D-type graphite cast iron can be used for producing an air-conditioning compressor cylinder body, has excellent thermal fatigue resistance and is long in service life.

Description

technical field [0001] The invention relates to the technical field of graphite cast iron. Background technique [0002] The carbon in ordinary gray cast iron generally exists in the form of flake graphite. According to its shape, flake graphite is divided into A, B, C, D, E, F and other types. The traditional point of view is that A-type graphite is evenly distributed, non-directional, and has less splitting effect on the matrix, so that cast iron has higher strength; D-type graphite is a point-like distribution between austenite dendrites without direction Or small flakes of graphite, known as dendritic graphite, is a harmful structure that reduces the hardness and strength of cast iron. However, a large number of studies in recent years have shown that compared with A-type graphite cast iron, D-type graphite cast iron has higher strength, denser, better dimensional stability, better resistance to thermal fatigue, and higher machining surface quality. For example, the ar...

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Problems solved by technology

In the prior art, it is generally believed that sulfur is a harmful element, and the lower the content in metals, the better. However, recent studies have pointed out that sulfur can reduce the solubility of carbon in molten iron, enhance the activity of carbon, and combine with manganese and rare earths. The formed sulfide can become the core of non-spontaneous nucleation of graphite, thereby ensuring the smooth progress of the inoculation reaction, but there is no example of applying sulfur to D-type graphite cast iron in the prior art

[0005] In short, the research on D-type graphite cast iron in the prior art needs to be strengthened, especially there is still a lack of an efficient, cheap, stable and simple production method for producing high-strength D-type graphite cast iron

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