Research progress in failure behavior of alloys for hot-section components in thermal power plant boilers under synergism of fireside corrosion and stress

Abstract

In response to the China's target of carbon peaking before 2030 and carbon neutralization before 2060, the steam parameters like steam temperature and pressure of thermal power generation need to be further increased to improve its thermal efficiency and reduce carbon emissions, which challenges the safety operation of thermal power plant. It is an important factor that the synergistic effect of high-temperature fireside corrosion and stress leads to the failure of alloys used for boiler, which is quite distinctive from the conventional stress corrosion cracking (SCC) since promising materials such as Ni-based superalloys are not sensitive to SCC tendency under the service condition of fireside corrosion coupled stress. Unfortunately, those impacts are often studied independently. The fireside corrosion mechanism and the stress failure of alloys were summarized in this paper, and the influential factors were pointed out from the materials (metal types, alloy elements and metal surface state) and the environments (temperature, corrosion atmosphere and coal-ash composition) that affect the corrosion performance of alloys. Furthermore, the failure mechanism of alloys from the perspective of the interaction between corrosion and stress was reviewed. On the one hand, the corrosion products deteriorate the creep rupture life of materials; additionally, the defects caused by stress will change the corrosion process of materials. Therefore, this paper focuses on the influence of the synergistic effect of high-temperature fireside corrosion and stress on the material performance, which is indicative for the design and performance of candidate materials for boiler environment of thermal power plants. As an example, the failure of Super304H under the fireside corrosion, creep and the synergism of fireside corrosion and stress were discussed. Finally, the prospect of future investigations on the interaction of fireside corrosion and stress was put forward, including the interaction between fireside corrosion and stress and the failure mechanism of materials under the synergistic effect.

Keywords

• fireside corrosion
• stress
• synergy
• failure
• thermal power plant