Introduction. The study is devoted to the analysis of the influence of the chemical composition of the 40КХНМ alloy on its hardness. The relevance of the work lies in the fact that mechanical tests require significant material and time costs. For the operational assessment of metal quality criteria, it is proposed to apply mathematical modeling in the work. Materials and methods. A study of the effect of the chemical composition on the hardness of the 40KHNM alloy, which meets the requirements of the state standard 51397, was carried out. The results of the experiment. In the course of research, it was found that changes in the chemical composition of the 40КХНМ alloy significantly affect its mechanical properties, including hardness and resistance to shock loads. An increase in the content of carbon, molybdenum and chromium in the alloy leads to an increase in its hardness. This is with the formation of stronger carbide and molybdenum phases in the structure of the alloy, which leads to an improvement in its mechanical properties. Increased hardness makes the alloy more resistant to wear and increases its durability in operating conditions. An increase in the nickel content in the alloy leads to an increase in its resistance to shock loads. This is caused by an increase in plasticity and impact toughness of the alloy with an increased nickel content. Higher resistance to shock loads makes the alloy suitable for use in conditions that require high resistance to shocks, for example, in the production of machine parts and equipment. A mathematical model of the dependence of the strength of the alloy on the percentage content of the components of the chemical composition was built, which allows to control the indicators of the strength of the alloy in the process of its manufacture. Conclusions. The research results confirm that changes in the chemical composition of the 40КХНМ alloy have a significant impact on its mechanical properties. As a result of the experiments, it was established that the chemical composition of the metal significantly affects the hardness of the material. By changing the composition of the metal, it was possible to achieve a significant increase in hardness to levels that meet the requirements of quality standards. These results are an important step in optimizing the production processes and improving the properties of the final products from the 40КХНМ alloy.