Three FeCrAl alloys (APMT, EF100 and EF101) from Kanthal® and the reference Ni-Cr Alloy 625 were used as weld cladding materials on tube shields in the evaporator tube bank of a waste-fired combined heat and power plant. For each alloy type, the overlay welded tube shields were placed in both roof and floor positions within the evaporator for 6 months. The metal-loss rate, the microstructure and hardness of the overlay welds before and after exposure and the corrosion products were analysed. The results showed higher metal-loss rates in the welds placed in the roof position, confirming heterogeneities in the evaporator bank environment. Alloys were ranked from higher to lower erosion–corrosion resistance as follows: APMT ≈ Alloy 625 > EF101 > EF100. The analysis of the corrosion attacks showed a significant variation among the alloys, from a primarily homogeneous corrosion attack on APMT to intergranular corrosion in EF100 and pit formation in EF101.
Alleima AB (formerly Sandvik Materials Technology AB), E.ON Värme Sverige AB and Kanthal AB are gratefully acknowledged for their participation and support in these research projects, and especially for providing the alloys, supporting the exposures in the boiler and valuable discussions. Eric Börjesson is acknowledged for performing valuable laboratory work at RISE and Kjell Hurtig is gratefully acknowledged for the preparation of the overlay welds at University West. Anna Jonasson is acknowledged for valuable planning and assistance regarding the exposure in the P14 plant at Händelö. This work was supported by the project, funded by the Stiftelsen för Kunskaps och Kompetensutveckling (KK‐stiftelsen) under Grant reference 20170316; and as part of the project KME‐802 , funded by the Swedish Energy Agency under Grant reference 46471‐1. HÖG‐FECRALCLAD Svetsbarhet och korrosionbeständinghet av nya FeCrAl‐legeringar Increased fuel flexibility and performance for boilers with challenging fuels