Сalculation and experimental studies of the residual resource of long-term strength of alloyed heat-resistant steels

The article is devoted to the fundamental research of the material for energy and chemical equipment in order to ensure operational reliability and long-term operation in conditions of high temperatures and corrosive environments. The paper presents a methodology for calculating the residual life of long-term strength of heat-resistant steels after their long-term operation at elevated temperatures to predict and determine the possibility of their further operation after the material’s service life has been exhausted without additional processing. For steel 10Kh2M, calculations are presented using the express method, tests are carried out for the long-term strength of this steel grade after its operation, and the obtained experimental and calculated data are analyzed. A study of the microstructure by optical metallography is presented, as a result of which the micro-damage of the material was assessed. The degradation score of the structure of samples of used material and samples after destruction during long-term strength tests of used steel was also determined. The changes in structure and the dependence character of the long-term strength of the used steel are analyzed, and the processes occurring during reuse are considered. Analysis of the data obtained indicates the restoration of the characteristics of the dependence of long-term strength at low loads and elevated operating temperatures, recommendations are given on the possibility of further usage of power and chemical elements equipment. In the process of carrying out the work, the possibility of using a statistical method for studying data on loads acting on metal at high temperatures was explored, which makes it possible to determine the negative consequences of operating conditions, increase the accuracy of predicting the residual service life of structural elements and use the obtained data for their reuse. The completed study was confirmed by the sufficient information content and reliability of the metallographic research method used to determine the damage to steel to make it possible to apply the proposed calculations to determine the residual life of steels.