The　microstructure　changes　underwent　by　the　heat-affected　zones　(HAZ)　of　a　X100　pipeline　steel　and　the　corrosion　behavior　of　these　zones　and　the　base　steel　were　studied　in　a　simulated　alkaline　soil　solution.　The　coarse-grained　heat-affected　zone　(CGHAZ)　and　the　intercritically　reheated　coarse-grained　heat-　affected　zone　(ICCGHAZ)　were　simulated　by　a　Gleeble　thermomechanical　processing　machine　with　different　thermal　cycle　times,　peak　temperatures,　and　cooling　rates.　Open　circuit　potential　(OCP),　potentiodynamic　polarization,　electrochemical　impedance　spectroscopy　(EIS),　and　scanning　electron　microscopy　(SEM)　were　used　to　characterize　the　corrosion　behavior　of　the　X100　pipeline　steel　and　its　CGHAZ　and　ICCGHAZ　in　a　simulated　alkaline　soil　solution.　The　microstructures　of　the　CGHAZ　and　ICCGHAZ　were　found　to　be　significantly　different　than　that　of　the　base　steel.　The　X100　base　steel　showed　the　most　positive　OCP,　the　lowest　corrosion　current　density,　and　the　largest　polarization　resistance.　In　contrast,　the　ICCGHAZ　showed　the　most　negative　OCP,　the　highest　corrosion　current　density,　and　the　lowest　polarization　resistance.　The　CGHAZ　and　ICCGHAZ　underwent　corrosion　to　a　higher　extent　compared　to　base　steel　after　immersion　in　a　simulated　soil　solution　for　similar　periods　of　time.　Those　samples　containing　HAZ　and　base　steel　were　found　to　present　significant　galvanic　corrosion.　The　CGHAZ　and　ICCGHAZ　of　a　X100　pipeline　steel　immersed　in　a　simulated　alkaline　soil　solution　exhibited　lower　corrosion　resistance　than　the　base　steel.