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

The paper presents the possibilities of renovation of worn functional surfaces of roll for continuous steel casting. The cylinder was made of steel 24CrMoV55 – DIN 17240. The lifetime of the continuous casting line roll is limited by the quality of their functional surface. The worn roll is decommissioned and the extent of its damage has been assessed. Cracks are a limiting factor in deciding on its renovation. Renovation of functional surfaces of roller from a diameter of ø 200 mm is realized by technology submerged arc welding (SAW). The article presents the results of research into the quality of newly formed cladding layers. Their quality was evaluated using non-destructive and destructive tests. Based on the performed experiments, it can be stated that the used surface renovation procedure is suitable for the renovation of functional surfaces of continuous steel casting rolls.

The paper presents the results of the research aimed at determining the quality of coatings applied by the HVOF spray coating technology and the advances in its application. WC-Co-Cr 86/10/4 nano covers were evaluated at two grain sizes. The effect of nano particle size on coatings quality was evaluated under abrasive wear conditions with bound abrasive in the initial state and after thermal cyclic loading. Coating thickness measurements, microhardness and structural analysis of the coatings were performed. As the number of thermal cycles increased, the hardness of the coatings increased. A thermal load between 600 and 800 ° C results in the crystallization of the amorphous phase, which leads to the precipitation of the WC phase from the Co-Cr matrix, and thus to an increase in the microhardness of the coating. The REM analysis of the structure of nano coatings confirmed that the exposure of the samples to the thermal load had an influence on their structural  composition. As the number of thermal cycles increased, the wear of the coatings under dry friction conditions increased.

The paper presents the results of the research of the evaluation of the overlay layers quality made by the fusible arc methods. By applying arc welding methods, it is possible to significantly extend the life of injection molds and thus significantly reduce production costs. The newly formed layers must meet a number of requirements so as not to degrade the advantages of high-pressure injection technology over conventional casting technologies. High pressure casting solves most of the problems of conventional casting technologies such as: porosity of the casting, high surface roughness, long casting time, inability to produce thin cross-sections and low dimensional accuracy. During exploitation, the mold surface is damaged, mostly by thermal cracking and combined adhesive-abrasive wear. Material used for high pressure die casting permanent mold is a medium alloyed hot tool steel Uddeholm Dievar. Layers were made using three types of filler materials on the Fronius TransTig 4000. To eliminate the effect of mixing, three layers were made. The quality of the deposits was assessed by non-destructive and destructive tests.

The paper presents results of quality evaluation of hardfacing layers applied to functional parts of dredger teeth. Layers were made by arc welding methods MMAW and FCAW. High-alloy types of filler materials were used in the experiment. Their chemical composition allows the production of overlay layers with a high content of carbide particles. These particles ensure high resistance to abrasive wear of the layers. Excavator teeth were made by casting high-grade manganese steels Grade B-3 A 128 / A128M-93. In the experiments, the presence of surface defects of the weld deposit was assessed by visual inspection. The resistance of the hard-facing layers to the effects of abrasive wear was assessed using a Di-1 experimental apparatus and evaluated on the basis of weight loss.