Dual-phase accelerated cooling (DPAC) was applied to X80 pipeline steel to obtain its microstructure with different amounts of bainite and ferrite. The microstructure, hardness, and polarization behaviors of the steel, cooled to different temperatures, were investigated. Results showed that, with decreasing cooling temperature, the amount of polygon ferrite (PF) increased while that of acicular ferrite (AF) decreased. The amount of bainite correspondingly decreased, except when cooled to 760°C. Moreover, the grain size of ferrite increased. The corrosion behaviors of different phases were distinct. Martensite/austenite (M/A) islands presented at the grain boundary of the PF phase caused small pits. Numerous micro-corrosion cells were formed in the AF and bainite phases, where micropores were prone to form. X80 pipeline steel cooled to 700°C had the best corrosion resistance in the simulated seawater. The decreased amount of the PF phase reduced the area of cathode, resulting in slight corrosion. About 40vol% of the bainite phase provided strength while the PF phase provided adequate ductility to the X80 steel. It was concluded that the appropriate cooling temperature was 700°C for ideal corrosion resistance and mechanical properties.

对X80管线钢进行了双相加速冷却（DPAC），以得到不同贝氏体和铁素体含量的组织。研究了冷却至不同温度的钢的组织，硬度和极化行为。结果表明，随着冷却温度的降低，多边形铁素体（PF）的数量增加，而针状铁素体（AF）的数量减少。贝氏体的量相应地减少，除非冷却到760℃。此外，铁素体的晶粒尺寸增加。不同相的腐蚀行为是不同的。出现在PF相晶界的马氏体/奥氏体（M / A）岛引起了小坑。在AF和贝氏体相中形成了许多微腐蚀孔，其中容易形成微孔。冷却至700°C的X80管线钢在模拟海水中具有最佳的耐腐蚀性。PF相的减少减少了阴极的面积，导致轻微的腐蚀。约40vol％的贝氏体相提供了强度，而PF相为X80钢提供了足够的延展性。结论是适当的冷却温度为700°C，以获得理想的耐腐蚀性和机械性能。