MATERIALS
Investgation properties of part – holder of breaking shoe beam made of SG60/SE300 steel cast
The main reason to perform this research investigation was to find a reason for appearing failures in exploratory condition of a part holder of breaking shoe beam. This part is incorporated in an assembly in railway wagon. This part together with few others was damaged in exploratory condition. It means that cracks were noticed on these parts. Some parts were completely broken. Because of that purchaser of parts complained of received parts to the producer. One of these parts was delivered to Prof Cvetkovski to find a reason and to give opinion about the reason for failure. The damaged parts are made of cast steel SG60/SE300. Many types of investigation was performed in order to solve this problem. As first visual control was done. After that, radiographic control was made. Investigations continued with determination of chemical composition and macro and micro metallography and determination of non-metallic inclusions. Finally mechanical testing like tensile testing, hardness measurement and impact toughness were performed too. Performed research confirmed that typical casting defects in the investigated part like the hot tears, slag inclusions, shrinkage porosity and segregation are the main reasons for failure of the delivered parts, holder of breaking shoes i.e. appearing of cracks or their completely fracture.