# Research on Roughness and Microhardness of C45 Material Using High-Speed Machining
## 1 Introduction  
Intensification and optimization of the machining process require a set of knowledge about the behavior of the material in the machining process, about the phenomena of mutual interaction between the tool and the workpiece, and about changes in the properties of the material in the machining process. The development of acquired knowledge and the formulation of scientific postulates leads to a rational choice of machining conditions characterized by minimal consumption of human labor, electrical and other types of energy, and tool material. Knowledge of the influence of cutting parameters on the formation of deformations in the cutting zone is essential from the point of view of all aspects of the production process. The significance and importance of this issue are confirmed by the publications of the authors at the global level. The authors [1] dealt with the issue of the influence of cutting parameters on chip compression and plastic deformation in the turning process of carbon and tool steel. From the conducted research, cutting parameters were selected, through which it is possible to achieve an increase in process efficiency for the investigated materials and, at the same time, an improvement in surface integrity with the identification of the lowest possible plastic deformation in the cutting zone. The same issue was investigated by the authors [2] but within the high-speed cutting process. In their research, they implemented the theory of stress waves to describe the mechanism of chip formation, followed by a quantitative DEM (discrete element method) analysis throughsimulation in comparison with experimentally obtained data. The authors [3] devoted themselves to investigating the influence of cutting parameters on chip formation for fiber-reinforced plastics. The research was carried out through real application parameters implemented in the industry. The achieved results pointed to the tendency of increased chip size when setting lower cutting speeds. The issue is investigated in connection with mechanical loading and chip formation [4; 5] and from the point of view of analyzing the microgeometry of the tool. The authors in [6] examined coated tools under different cutting conditions in terms of wear and topography. The research of the surface topography depending on the cutting parameters was also described in [7], where the microstructure, hardness, and roughness in the process of conventional titanium milling were investigated. The effects of microbrication and two alternatives of cryogenic cooling in the titanium hole-making process were also investigated [8], which is considered highly unsustainable, as it is disturbed by poor hole quality, high energy consumption, and is also accompanied by damage to tools, resulting in high costs for the production process. From the results, conclusions were identified with the determination of suitable parameters for the given machining processes, which ensured a higher overall efficiency of the production process. The same material was investigated, and the results of the performed experiment were described by the authors [9], but the authors focused on the study of surface topography in the process of high-speed machining. Based on the performed experiments, they came to the conclusion that the surface topography is significantly influenced by the depth of cut, while the feed rate and cutting speed do not have a significant effect on the topography. The issue of optimization of machining parameters of titanium alloys using the MOORA method (multi-objective optimization based on ratio analysis) is presented in the article by [PERSON] et al. [10], summarizing in the discussion part the knowledge about the possibilities of achieving a balance between achieving lower values of surface roughness at the highest possible permitted material removal rate.