The influence of alloying elements on metal dusting behavior of nickel chromium alloys and their statistical correlation

The focus in this study is on very metal dusting resistant nickel chromium alloys with a high content of chromium (in the range of 22 to 33 wt.%), additions of aluminum (between 0 and 3 wt.%) and variable iron content (between 0.1 and 15 wt.%). All samples were exposed up to 5693 h at 600 °C in a 37 vol.% CO, 7 vol.% CO 2 , 46 vol.% H 2 , 9 vol.% H 2 O atmosphere at a total pressure 20 bar. The differences between the samples in terms of mass loss, pit depth and incubation time to first pit are evaluated by a statistical analysis and discussed in dependence of alloy composition. Only samples with combined chromium plus aluminum content of about 30 wt.% or more and an iron content of 0.6 wt.% or less do not show any pit formation during the exposure time, even on the edges. In contrast, samples with a similar combined chromium plus aluminum content, but with a higher iron content, do show pit formation due to metal dusting corrosion.