Studies were conducted on a zinc coating produced on the surface of ductile iron grade EN-GJS-500-7 to determine the eutectic grain

effect. For this purpose, castings with a wall thickness of 5 to 30 mm were made and the resulting structure was examined. To obtain a

homogeneous metal matrix, samples were subjected to a ferritising annealing treatment. To enlarge the reaction surface, the top layer was

removed from casting by machining. Then hot dip galvanising treatment was performed at 450°C to capture the kinetics of growth of the

zinc coating (in the period from 60 to 600 seconds). Analysing the test results it was found that within the same time of hot dip

galvanising, the differences in the resulting zinc coating thickness on samples taken from castings with different wall cross-sections were

small but could, particularly for shorter times of treatment, reduce the continuity of the alloyed layer of the zinc coating.

The FMEA (Failure Mode and Effects Analysis) method consists in analysis of failure modes and evaluation of their effects based on

determination of cause-effect relationships for formation of possible product or process defects. Identified irregularities which occur

during the production process of piston castings for internal combustion engines were ordered according to their failure rates, and using

Pareto-Lorenz analysis, their per cent and cumulated shares were determined. The assessments of risk of defects occurrence and their

causes were carried out in ten-point scale of integers, while taking three following criteria into account: significance of effects of the defect

occurrence (LPZ), defect occurrence probability (LPW) and detectability of the defect found (LPO). A product of these quantities

constituted the risk score index connected with a failure occurrence (a so-called “priority number,” LPR). Based on the observations of the

piston casting process and on the knowledge of production supervisors, a set of corrective actions was developed and the FMEA was

carried out again. It was shown that the proposed improvements reduce the risk of occurrence of process failures significantly, translating

into a decrease in defects and irregularities during the production of piston castings for internal combustion engines.