Investigation of the metal dusting attack on the temperature range 500−700 °C using X-ray tomography

Abstract A test rig consisting of a quartz tube placed in a horizontal furnace made of five independently regulated heating zones allowed the evaluation of the metal dusting attack of a FeNiCr alloy. Fifteen samples were exposed in a temperature gradient from 504° to 704°C, 1.1 bar, to a highly carburizing atmosphere for 1500 h. Below 561 °C the high density of pits led to uniform corrosion whereas localized pits developed at higher temperatures. In depth pit growth rate raised to a maximum at 632 °C, then decreased showing that it depends both on temperature and on the carbon activity gradient.