Effect of Decarburization Heat Treatment and Chromium Addition on Corrosion Behavior of Carbon Steel

Effect of decarburization heat treatment (DHT) and 0.3 wt% to 0.4 wt% chromium addition on corrosion behavior of ASME SA 106 (UNS K03006) carbon steel was investigated by performing electrochemical measurements. Optical microscopy, scanning electron microscopy, and energy-dispersive analysis spectroscopy were performed to clarify the change of microstructure caused by DHT and chromium addition. The experimental results show that DHT changes the microstructure consisting of two phases (pearlite and ferrite) to one phase (ferrite), and the ferrite phase coarsens as the time of heat treatment increases. These microstructural and compositional differences before and after the DHT and chromium addition change the electrochemical corrosion potential (ECP) and repassivation behavior of the SA 106 specimens.