Increase of wear resistance of cast iron by the directed of structure formation of his matrix with vermicular graphite
DOI:
https://doi.org/10.31891/2079-1372-2019-93-3-74-84Keywords:
vermicular graphite, microalloying, perlizating, wear resistance.Abstract
The study was made of cast iron with vermicular graphite of the mark CIVG 300-4, for the production of which it was used the melts with a composition close to the eutectic, modified with the VL 63 (M) TS lag containing Mg = 6.5 %, Ca = 1.8 %, Si = 46 %, RZM = 0.7 %, Fe - the rest. The results of the influence on the structure of the metal matrix, modification conditions and formation of vermicular graphite are given. Perlite areas located between eutectic colonies of vermicular graphite as the place of formation of phosphide inclusions and micropores are revealed. It is determined that increase in dispersion of inclusions of vermicular graphite leads to a decrease in mechanical properties by reducing the compactness of graphite inclusions and increasing the ferritization of the metal base. Influence of residual magnesium content in different structures of graphite is given. The influence of the thickness of the cross-section of casting on the content of perlite in the structure of the metal matrix of cast iron with vermicular graphite, the change of its structure with acceleration of cooling of casting and the character of the distribution of Si, Mn, Cr and P are studied. It has been found that the use of antimony as a perlizator complicates its strong deglobuliratory action, and chrome by bleaching effect. It has been determined that microleagulation by chromium provides only up to 60 ... 65 % perlities, and the addition of 0.3% copper can increase the perlite content up to 80 %. It has been shown that despite the higher degree of perlization, the hardness of pig iron with vermicular graphite with microleagulation by antimony in all cross sections is lower than with microleagulation by chromium. At the same time, the reduction of the microhardness of perlite by the addition of antimony can be a promising method of providing increased wear resistance of cast by the iron with vermicular graphite.
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