The examination of the effects of strontium content on the properties of cylinder heads

Abstract

During the experiments AlSi8Cu3 alloy was alloyed with strontium in different concentrations. The effect of strontium on the silicon in the eutectic structure was examined under operating conditions, in case of both higher (>100 ppm) amount of strontium content than usual in operating conditions and lower (~100 ppm) amount of strontium content, which is not used in practice. The extent of modification in the test bars casted during thermal analysis and in the final castings was determined with the help of cooling curves and by comparing them to images of reference standards. The reason for using these two methods was to determine the correlation between the levels of modifications determined by both the temperature of supercooling, which can be calculated from the cooling curves, and the structure evaluation methods. The mechanical properties of castings casted under the given cooling conditions were also examined. The fractures and microsections of the tensile test bars were examined with stereo microscope and scanning electron microscope.