Several candidate materials were evaluated by corrosion testing in autoclaves containing white and black liquors for batch digesters. The relationship between corrosion rate and corrosion potential was determined for ASTM SA516-Grade 70 carbon steel, UNS S30403 (Type 304L) auatenitic stainless steel, UNS S3 1803 (“2205”) and UNS S32550 (“2605”) duplex stainless steels, and two stainless steel weld overlays, applied by the GMAW(’gasmetal arc welding)and SAW(submerged arc welding) processes. The tests revealed that SA5 16-Grade 70 carbon steel and type 304L stainless steel cm experience high rates of corrosion. For the duplex stainless steels and weld overlays, corrosion resistance ieuproved with chromium content. A chromium content of at least 25% was found to be necessary for good corrosion resistance.
Keywords: austenitic stainless steel, black liquor, carbon steel, corrosion testing, duplex stainless steel, pulp and paper, thermal spray, weld overlay, white liquor.