In　recent　years,　many　accidents　caused　by　alternating　current　(AC)　corrosion　have　been　reported.　AC　corrosion　has　become　a　serious　potential　damage　to　buried　steel　pipelines.　The　X100　pipeline　steel　is　a　very　promising　material　for　long-distance　gas　pipelines,　and　Korla　soil　is　a　typical　saline-alkali　soil　of　West　China.　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　through　different　thermal　cycle　times,　peak　temperatures,　and　cooling　rates.　Electrochemical　corrosion　measurements,　immersion　experiments　and　surface　analysis　techniques　were　used　to　characterize　the　corrosion　behavior　of　the　base　metal,　CGHAZ,　and　ICCGHAZ　of　the　X100　pipeline　steel　in　simulated　Korla　soil　solution　under　AC　interference.　The　X100　pipeline　steel　base　metal,　CGHAZ,　and　ICCGHAZ　exhibited　active　dissolution　in　the　simulated　Korla　soil　solution　under　AC　interference,　and　the　average　corrosion　rate　increased　with　the　increase　in　AC　density.　The　amplitude　of　the　polarization　potential　oscillation　caused　by　AC　interference　and　the　microstructure　had　an　important　influence　on　the　corrosion　rate　and　corrosion　morphology　of　the　X100　pipeline　steel　base　metal,　CGHAZ　and　ICCGHAZ.　Under　the　interference　of　5　mA·cm-2　AC　density,　the　X100　pipeline　steel　base　material　shows　the　most　negative　corrosion　potential　and　the　largest　average　corrosion　rate,　while　the　ICCGHAZ　shows　the　most　positive　corrosion　potential　and　the　smallest　average　corrosion　rate.　Under　the　interferences　of　20　and　50　mA·cm-2　AC　densities,　the　ICCGHAZ　of　X100　pipeline　steel　shows　the　most　negative　corrosion　potential　and　the　largest　average　corrosion　rate,　while　the　base　metal　shows　the　most　positive　corrosion　potential　and　the　smallest　average　corrosion　rate.　Under　the　interference　of　20　mA·cm-2　AC　density,　the　X100　pipeline　steel　is　locally　corroded.　CGHAZ　and　ICCGHAZ　have　obvious　grain　boundary　corrosion,　whereby　GCHAZ　grain　boundary　corrosion　morphology　is　slit-shaped,　and　ICCGHAZ　grain　boundary　corrosion　morphology　is　continuous　pores.　©　2020,　Science　Press.　All　right　reserved.