The main goal of the presented research is to assess the technological damageability of the material, which can be used as a criterion for analyzing the technological route of product machining in the "blank-workpiece-final part" technological chain. This technological chain is examined in detail in the most important stages of the life cycles of mechanical engineering products in order to take into account the principles of technological inheritability of their characteristics and quality parameters. The technological inheritability of the properties of the surface layers of machines and mechanisms parts from steel during their machining evaluates and predicts the transformation of the structurally heterogeneous material obtained after the production of blanks into the structurally homogeneous material of the final parts. The procedure for evaluating the homogeneity of the processed material for each technological step by the LM hardness method is presented. The developed methodology was implemented and proven during the manufacturing process of the conveyor belt drive drum shaft.

The aim is to overcome the issues of high-hardness material welding by different additives used to achieve the desired improvements. The research is focused on Hardox 450 steel welding and factors to be considered in order to maintain the required mechanical properties of the weld. The selection of best suited welding materials or additives, including filler metals and shielding gases, are within the important factors to be taken into account. During the welding of Hardox 450 steel, cobalt, nickel, tungsten and titanium additives and cobalt and tungsten mixture additives were used and their influence on the microstructure and mechanical properties of the fusion and heat-affected zones was investigated. The microstructure of the weld zone is related to certain mechanical properties of the weld and heat-affected zone, such as hardness, tensile and bending strength, yield strength, strain at ultimate tensile strength, the Young’s modulus and elongation. Research has shown significant differences in the mentioned parameters depending on specific additives used in the welds. It can be concluded that tungsten, used as an additive, increased the hardness of the heat-affected and fusion zones up to 478 HV; the combined presence of cobalt and tungsten additives improves the strength of the seam up to 744 MPa during tensile; and in the case of bending, nickel, when used as an additive, increased ductility (the bending modulus reached the limit of 94 GPa) and at the same time, decreased the risk of cracking. The obtained results highlight the possibilities for strengthening the welded joint of Hardox 450 steel using different additives or their mixtures. The research conclusions and recommendations aim at improving the quality and mechanical properties of welded Hardox 450 steel joints in various applications.

The results of the computer simulation of the cutting process of gears by the power skiving method are presented. Following the kinematics of the process, a method for generating 3D geometric models of undeformed sheared layers were developed, and their parameters were analyzed. The influence of tool geometry and technological parameters on cutting conditions is investigated. The simulation results and calculation of the tangential force and torque on the tool axis and their influence on the error due to angular elastic deformation of the tool are given.