采用微观组织观察和准静态拉伸试验分析了冷速对X80管线钢的淬火双相组织及其应变硬化行为的影响。结果表明：，X80管线钢通过淬火热处理获得铁素体+贝氏体的双相组织；随着冷速的降低，铁素体体积分数增加，强度降低，均匀伸长率增加；当铁素体体积分数不小于5.27%时，应变硬化指数与材料的均匀伸长率正相关，与屈强比负相关；当铁素体体积分数达到22.8%时，加工硬化率经历先快、后慢的两个下降阶段，后一阶段推迟了颈缩变形；淬火组织中的贝氏体随着冷速的降低，形貌由板条状转变为粒状，并生成了MA组元，通过位错强化、第二相强化机制的转换保证加工硬化性能，提高了均匀塑性变形能力。

In the investigation, the microstructural observation and quasistatic tension experiments of X80 pipeline steel were conducted so as to reveal the effects of the cooling rate on its quenched dual-phase microstructure formation and strain-hardening behavior. The results show that (1) a dual-phase microstructure including ferrite and bainite is obtained after X80 pipeline steel is quenched; (2) the ferrite volume fraction and the uniform elongation increase with the decrease of the cooling rate while the strength decreases; (3) when the ferrite volume fraction is not less than 5.27%, the strain-hardening exponent has a positive correlation with the uniform elongation but a negative correlation with the yield ratio; (4) when the ferrite volume fraction reaches up to 22.8%, the work-hardening rate decreases with a fast stage and then a slow stage, and the latter stagethe later stage delays the necking point; and (5) with the decrease of the cooling rate, the lath-like bainite in the quenched microstructure turns to be granular and MA phase forms, simultaneously, the strain-hardening performance of the quenched microstructure is guaranteed and the uniform plastic deformation ability is improved by means of the conversion of the dislocation strengthening to the second phase strengthening.