Development of Weldments for Sulfur-Containing Combustion Environments

Alloys Incology 800 H, RA 333 and Haynes 188 weldment materials were exposed in TVA 20-MW and Rocketdyne atmospheric fluidized bed combustors (AFBCs) at 849{degrees}C for 1261 and 871{degrees}C for upto 1980 h, respectively. Postexposure analyses were conducted at Argonne National Laboratory. All specimens experienced different degrees of internal oxidation/sulfidation. Among eight filler materials, Marathon 25/35R and Haynes 188 showed the least corrosion attack, i.e., less than 0.5 mm/yr. A high nickel content in the weldment was unfavorable for corrosion resistance in the AFBC environment. Differences in the coal/bed chemistry of the TVA and Rocketdyne systems yielded different corrosion behavior in the materials. Calcium sulfate deposits on the specimens significantly affected the internal oxidation/sulfidation of the alloys. The results of this study supplement the material data base, in particular that of weldment performance, and aid in materials selection for AFBC applications.