A study on improvement of replication method by applying electrolytic polishing technique

摘要

Remaining life evaluation of fossil power plants and petrochemical industry has been considered important to ensure the integrity and safety for these industrial equipments. Among the known various life assessment methods,surface repli-cation technique which allows indirect observation and analysis of the metallographic microstructure of equipment is widely used to detect creep damage nondestructively,which widely occurs in high temperature components. One of the significant requirements at the inspection location is to make sure to conduct the right pre-treatment i.e.,to make the met-allographic microstructure not to be bothered by dust or other contaminated materials and to maintain the environment clean. In this study,as a candidate of the pre-treatment procedure electrolytic polishing technique is proposed. After ap-plying the electrolytic polishing the results of obtained microstructures were compared with those obtained by the conven-tional technique. Advantage and disadvantage of the proposed method were discussed. It was confirmed that the electro-lytic polishing can be successfully remove the problems of the conventional mechanical polishing and improve the results.I was possible to accurately determine the existence and nonexistence of the cavities which usually occur near the crack region. However,it should be noted that when quantitative life assessment method based on the number or the size of the creep cavity is applied,revised data should be applied in evaluation,not by the existing data obtained by the mechanical polishing method.