Corrosion Behavior of X100 Pipeline Steel and Its Heat-Affected Zones in Simulated acidic Soil Solution

摘要

Different thermal cycle times, peak temperatures, and cooling rates were used in a Gleeblethermomechanical processing machine to simulate the coarse-grained heat-affected zones (CGHAZ) andinter-critically reheated coarse-grained heat-affected zones (ICCGHAZ) of X100 pipeline steel. Thecorrosion behavior of the X100 pipeline base steel and the heat-affected zones (HAZs) were studied ina simulated acidic soil solution. Open circuit potential (OCP) measurements, potentiodynamicpolarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM),energy dispersive x-ray spectroscopy (EDS), and weight loss testing were used to characterize thecorrosion behavior of X100 pipeline steel and its CGHAZ and ICCGHAZ in a simulated acidic soilsolution. The microstructures of the CGHAZ and ICCGHAZ were found to be significantly differentfrom that of the base steel. The original X100 pipeline steel showed the most positive OCP, the lowestpolarization resistance, and the highest corrosion rate. The ICCGHAZ showed the most negative OCP,but CGHAZ showed the highest polarization resistance and the lowest corrosion rate. The corrosionproducts of X100 pipeline steel base material, CGHAZ and ICCGHAZ all form a layer covered withcracks, which provides poor protection for the substrate. Immersed in a simulated acidic soil solution,the X100 pipeline steel base metal samples were uniformly corroded, while CGHAZ and ICCGHAZsuffered severe intergranular corrosion.