Effects of silicon and titanium on the corrosion of low-alloy steels in a simulated coal gasification environment at 600 degrees C

Results of corrosion tests carried out on a series of Fe-12% Cr alloys in c oal gasification environments at 600 degrees C were studied. Effects of Si and Ti on corrosion resistance were assessed using data obtained from a com mercial 12% Cr alloy, type 410 (UNS S41000), three specially cast "model" 1 2% Cr alloys containing 2.7% Si with Ti levels of 0%, 0.4% and 0.7%, respec tively, and a higher alloy (type 28 [UNS N08028]) heat exchanger steel. Cor rosion tests were carried out using a simulated dry-feed entrained slagging gasifier gas. The gas (64% carbon monoxide [CO], 3.8% carbon dioxide [CO2] , 0.8% hydrogen sulfide [H2S] and balance H-2 [in vol%]) was premixed and p assed over the test pieces at a rate high enough to prevent thermodynamic e quilibrium achievement Results showed that Si had a strongly beneficial inf luence on corrosion resistance. Ti, depending upon the amount added, exerte d a positive or negative influence on corrosion resistance and reduced prob lems associated with workability, The kinetics of corrosion. were presented in terms of weight-change and metal-loss measurements, the synergistic inf luences of Si and Ti were discussed, and corrosion resistance was compared with that exhibited by a commercial 12% Cr steel and type 28, the higher al loy material.