High-strength gray cast iron modifier and modification treatment process thereof

Abstract

The invention relates to a high-strength gray cast iron modifier and a modification treatment process thereof. The modifier mainly comprises the following chemical components in percentage by weight: 30-50 percent of V, 5-10 percent of N, 5-10 percent of RE, 5-10 percent of Ca and the balance of Si. The modification treatment process comprises the following steps of: filling the modifier into the bottom of a gray cast iron casting ladle by using a cast iron casting ladle flush-in method; pouring into the casting ladle when temperature of molten gray cast iron reaches 1,480-1,550 DEG C; melting the modifier by the high-temperature molten iron; and feeding elements in the modifier into the molten iron to obtain high-strength gray cast iron. Primary austenite dendritic crystals are obtained from the gray cast iron and are fine, and the number of the primary austenite dendritic crystals is increased; the thickness of laminates of pearlite clusters is reduced, the space of the laminates is reduced, and the laminates are arranged in a staggered way; the number of graphite is increased, the graphite is fine and bent, and the tip is passivated; and thus, the strength of the gray cast iron is obviously improved, and the tensile strength of the standard test rod reaches 400 MPa.

Description

technical field [0001] New material - the present invention "a high-strength gray cast iron modification agent" relates to a new type of modification agent used to improve the strength of gray cast iron, in particular to a preparation technology for high-strength gray cast iron. Background technique [0002] Gray cast iron is a traditional structural material with a long history. Scientific researchers and engineers all over the world have been working hard to improve the strength of gray cast iron. At present, the recognized mechanism for improving the strength of gray cast iron has the following four aspects: (1) increasing the number of primary austenite dendrites; (2) refining the spacing of pearlite sheets; (3) refining graphite and bending graphite and passivation; (4) refine the eutectic group. [0003] In order to improve the strength of gray cast iron, cast iron scientific and technological workers at home and abroad have carried out a lot of research work on the ...

AI Technical Summary

Problems solved by technology

At present, the highest tensile strength of a standard test bar with a diameter of 30 mm and a length of 280 mm cast in a green sand mold of micro-alloyed gray cast iron reported in the world is 395 MPa. For details, see the invention patent "Micro-alloyed high Strength gray cast iron" (patent number: 2005100168785), has not yet reached above 400 MPa

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