分别采用计算法、膨胀法和差示扫描量热（DSC）法对热轧态Q345钢的临界点进行了测定与分析，系统讨论了3种测定方法的准确性、一致性和适用性。结果表明：计算法、膨胀法、DSC法所测定的临界点结果具有一致性，热轧态Q345钢的临界点A_c1和A_c3分别约为730℃和860℃；对于热轧态Q345钢临界点的测定，如使用膨胀法推荐依据YB/T 5127-1993的方法进行测定，如使用DSC法推荐以10~20℃ ·min^-1的升温速率进行测定。

The critical points of hot rolled Q345 steel were determined and analyzed by calculation method, expansion method and differential scanning calorimetry (DSC) method, respectively. The accuracy, consistency and applicability of the three measuring methods were discussed systematically. The results show that the critical points determined by calculation method, expansion method and DSC method were consistent. The critical points of A_c1 and A_c3 of hot rolled Q345 steel were about 730 and 860℃, respectively. For the determination of the critical points of hot rolled Q345 steel, the expansion method is recommended to be based on YB/T 5127-1993, and the DSC method is recommended to be used at the heating rate of 10-20℃ ·min^-1.