Technological audit of modifying cast iron for casting autombile and road machinery

Abstract

Quality control of machine-building parts implies considering the issues related to obtaining high-quality alloy. The right choice of alloy modification process, depending on the type of modifier and the way of its application, is foreground. The difficulty in adequate selection of these parameters is a problem for efficient task solution. The experience of experimental and industrial examinations was described in the paper that allowed formulating a number of significant conclusions, concerning a reasonable choice of a modifier, based on compromise criteria, concerning the necessity of increasing modification process quality on the one hand, and reducing expenses of a company, related to purchasing or irrational application of expensive modifiers on the other hand. It was shown, that the choice should be based on conducting metallographic analysis of the microstructure of cast iron, treated with the compared types of modifiers in the core zone and periphery of a wedge sample and their “linking” with minimal thickness of casting section, produced under certain industrial conditions. The result of such analysis for each parameter of the microstructure and each of compared modifiers is the construction of histograms, describing the distribution of a qualitative feature of the estimated parameter, and their further comparison. The obtained difference of mathematical expectations of estimated microstructure parameters for the compared modifiers is the qualitative estimation of efficiency of the compared modifiers. The method can be recommended to industrial enterprises, producing shaped castings for machine-building parts.