Microstructure, properties investigations and methodology of the state evaluation of T23 (2.25Cr-0.3Mo-1.6W-V-Nb) steel in boilers application

Purpose: The purpose of the paper is to work out the classification of the structure’s changes and the development of precipitation processes and the internal damages related to the exhaust degree of material working in creep conditions to use in the materials diagnostics. Design/methodology/approach: Examination results were made on materials in initial state, after long-lasting annealing and after creep trials. Investigations of the structure were made by the use TEM, and morphology of internal damages resulting from creep were made by the use of scanning electron microscope. Findings: The paper presents investigation results in the area of the changes of mechanical properties and structure of the T23 steel resulting from the long term impact of temperature and load in conditions corresponding to the service ones. The influence on mechanical properties and structure after long-lasting temperature and load exposition was estimated. Schemes of structure changes and inner failures after exposition in creep condition were worked out. Practical implications: The worked out methodology of evaluation of the material’s state after exploitation in creep conditions can be use in the material’s diagnostics of element working in power industry. Originality/value: Classification of the structure changes and development of precipitation processes and internal damages as a result of creep.