International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

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.

An aim of a research was to determine the reasons of fracture of aluminium alloy components used for spinning of chemical fibres and to improve spinning process by selecting material with better performance.

Analysis of material condition of side frames of freight trucks before and after thermal hardening was performed by combined analysis of Acoustic Emission (AE) and strain diagrams during tests of samples cut from the frames. The kinetic of damage accumulation during loading to failure in the material after normalizing or volume-surface hardening was analyzed. Changes in ductility and toughness resource of the metal was evaluated.