Method for eliminating casting shrinkage cavity defect by using petroleum coke carburant

Abstract

The invention discloses a method for eliminating a casting shrinkage cavity defect by using a petroleum coke carburant. The method comprises the following steps that a first batch of carbon steel scrap is added into the petroleum coke carburant for being mechanically stirred uniformly, and then added into the middle-lower part of a medium-frequency smelting furnace; a second batch of carbon steel scrap is added into the middle-upper part of the medium-frequency smelting furnace, and heating is carried out until the carbon steel scrap is completely molten into molten steel; after the molten steel is completely melted down, magnetic stirring is carried out, and after carbon components in the furnace are uniform, sampling is carried out for spectrum sample component analysis; and the components are adjusted after sampling, and various elements are added according to requirements. The petroleum coke is added at the initial stage of the smelting furnace, so that the dissolving speed of the petroleum coke can be guaranteed, graphite carbon is effectively prevented from forming graphite floating in a casting, spheroidizing recession of graphite is effectively prevented, graphitizing expansion in a matrix is fully exerted, shrinkage porosity and shrinkage cavity defects of a hot spot part in the casting are effectively prevented, raw material waste is reduced, and the production cost is reduced.

Description

technical field [0001] The invention relates to the technical field of metal smelting, and more specifically relates to a method for eliminating shrinkage cavity defects of castings by using a petroleum coke recarburizer. Background technique [0002] The fork ring is the main stress-bearing part of the engineering vehicle, and the material is QT600~3. The technical requirements are that there should be no shrinkage and shrinkage defects inside the part. [0003] In the early stage of the fork ring, graphite recarburizer was used to increase carbon. After dissection, it was found that there were shrinkage defects in the casting near the hot joint, and the defect ratio was about 45%. The graphite recarburizer diffused and dissolved faster, and the particles of free carbon in molten iron Large, up to 0.025mm, the free graphite near the hot spot floats up during the solidification of molten iron, causing graphite to float in the metallographic structure. [0004] Free carbon g...

AI Technical Summary

Problems solved by technology

[0004] Free carbon gradually aggregates and grows near the hot spot during the solidification of molten iron, and the graphite spheres in the matrix become larger and produce irregular shapes, resulting in the decline of spheroidization. The combined carbon forms pearlite sheets during the solidification process. Thickness is relatively large , the ferrite sheet in the carbon-poor area is also thick, which hinders the further spheroidization of free carbon. During the solidification process, the expansion of free spherical graphite cannot be fully utilized, and shrinkage porosity and shrinkage defects will occur in the area close to the hot spot.

Images