将X80管线钢加热到奥氏体化温度以上（920℃）并保温7 min后，在不同冷却介质（质量分数10% NaCl溶液、自来水、机油、空气，冷却速率依次降低）中冷却，研究了其显微组织和力学性能。结果表明：随着冷却速率的降低，试验钢的强度和硬度降低，塑性增大，冲击功先增大后减小；在较高速率下冷却（NaCl溶液和自来水）后，组织中生成了贝氏体铁素体和少量马氏体板条，马氏体板条内有大量位错结构和少量碳化物，试验钢具有高的强度和低的变形能力；在较低速率下冷却（空气）后，组织中形成了多边形铁素体、贝氏体铁素体和少量块状马氏体-奥氏体组织，试验钢的强度和冲击韧性较低；在适中冷却速率下冷却（机油）后，组织中形成了贝氏体和铁素体的双相组织，多位向分布的细小贝氏体和邻近贝氏体的高密度位错铁素体使得试验钢具有良好的综合力学性能和较高的抗大变形能力。

X80 pipeline steel was heated to above the austenitizing temperature (920℃), held for 7 min, and cooled in different cooling media (10wt% NaCl solution, tap water, engine oil, air, cooling rate decreased in turn). The microstructure and mechanical properties were studied. The results show that with decreasing cooling rate, the strength and hardness of the test steel decreased, the plasticity increased, and the impact energy increased first and then decreased. After cooling at relatively high rates (in NaCl solution and tap water), bainite ferrite and a few martensite laths were formed in the microstructure, and many dislocation structures and a few carbides were found in martensite laths; the test steel had high strength and low deformability. After cooling at a relatively low rate (in air), polygonal ferrite, bainite ferrite and a few block martensite-austenite structures were formed in the microstructure; the strength and impact toughness of the test steel were low. After cooling at a moderate rate (in engine oil), a duplex structure of bainite and ferrite was formed in the microstructure; the multitude direction distributed bainite and high density dislocation ferrite adjacent to bainite led to good comprehensive mechanical properties and high resistance to large deformation of the test steel.