针对大棒材轧后冷却工艺中的尺寸效应问题,建立了42CrMo不同直径(φ25~φ150 mm)棒材轧后冷却过程温度—组织耦合非线性有限元模型。通过数值模拟,对比分析了空冷、风冷、雾冷和水冷条件下,棒材直径对工件内部温度场、温降速率和组织分布均匀性的影响规律,研究了大棒材轧后控冷工艺的尺寸效应,并通过冷却实验验证了数值模型的正确性,这能为线棒材轧后控冷工艺制定与优化提供重要依据。 Aiming at the problem of size effect in the cooling process of large bar rolling, a nonlinear finite element model of temperature-tissue coupling in cooling process of 42CrMo bar with different diameters (φ25 ~ φ150 mm) was established. Through numerical simulation, the effects of air-cooling, air-cooling, fog-cooling and water-cooling conditions on the temperature field, the rate of temperature drop and the distribution uniformity of the workpiece under the bar diameter were analyzed. The size effect is verified. The numerical simulation is validated by the cooling experiment, which can provide an important basis for the formulation and optimization of the controlled cooling process after wire bar rolling.