Casting technology of automobile brake disk

Abstract

The invention relates to a process for casting automobile brake discs, which is implemented according to a conventional casting process. mixture ratio adopts the following parameters: (1) the chemical constituents in weight percentage of a casting are: 3.70 to 3.75 percent of C, 2.10 to 2.20 percent of Si, 0.80+-0.05 percent of Mn, less than 0.15 percent of P, 0.07 to 0.12 percent of S, less than 0.30 percent of Cu, 0.030 to 0.035 percent of Sb and less than 0.01 percent of Sn; and (2) meanwhile, 70SB-1 transient inoculant is added, and the addition amount of the inoculant in weight percentage is 0.1 percent. The process has the advantages that the casting process for automobile brake disc castings which adopts the chemical constituents and adds the transient inoculant can eliminate corpulent graphite tissues inside the casting, ensures that no shrinkage porosity tissues can be generated inside the casting, obviously improves the quality of the casting, and can particularly raise the qualified rate of the casting after turning greatly.

Description

(1) Technical field [0001] The invention relates to a casting process, in particular to a casting process of an automobile brake disc. (2) Background technology [0002] With the development of technology in the automotive industry, the requirements for auto parts are getting higher and higher. Automobile brake discs are one of the most important parts in auto parts. In order to ensure the processing quality of auto brake discs, the chemical composition, metallographic structure, graphite form, tensile strength, hardness, etc. have stricter requirements. The currently controlled specification is, chemical composition: C 3.6-3.8%, Si 2.3-2.55%, Mn 0.5-0.9%, P<0.15%, S<0.12%, Cu<0.3%; metallographic structure: ferrite <15%, cementite <5%, pearlite>80%; graphite form: mainly A type and B type, a small amount of C type is allowed, graphite size is 2-4 grade; tensile strength ≥ 120Mpa; hardness HB156-201; Shrinkage and porosity are not allowed. In actual pro...

AI Technical Summary

Problems solved by technology

In actual production, it is very difficult to make automobile brake disc castings meet the above chemical composition and graphite form requirements at the same time, that is, the above chemical composition requirements are difficult to ensure graphite form

In actual production, due to the large amount of C-type graphite in the casting, the graphite structure is hypertrophic, making it difficult to guarantee the roughness after turning; in order to eliminate the disadvantages of graphite hypertrophy, the method of adding trace element Sb is usually used to hinder graphitization and promote pearlescent However, if the addition ratio of Sb is inappropriate, it will lead to a greater tendency to produce shrinkage porosity inside the casting, resulting in a significant increase in the failure rate of the casting after turning, and sometimes the failure rate is as high as 20%.