ABSTRACT The effects of cooling modes (air, furnace and water) on the variation of microstructure and mechanical properties of medium carbon steel were investigated. SEM, TEM and EBSD techniques were used to observe the microstructure. The observed results show that the effect of cooling mode on the grain size is insignificant. The average sizes of ferrite grain obtained under different cooling modes were little different. Moreover, in all the cases, most of the cementite lamellas were transformed into cementite particles, except for some of the residual cementite lamellas which were present on the original pearlite colonies. It has also been found that the ferrite substructure and precipitation of cementite particles are significantly affected by the cooling modes. Compared to other cooling modes, the furnace cooling is beneficial to the homogeneity of microstructure. The particles are distributed on the ferrite matrix more homogeneously after furnace cooling which results in a better combination of strength and ductility.

中文翻译：

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冷却方式对中碳钢温轧后组织和力学性能的影响

摘要 研究了冷却方式（空气、炉和水）对中碳钢组织和力学性能变化的影响。SEM、TEM和EBSD技术用于观察微观结构。观察结果表明，冷却方式对晶粒尺寸的影响不显着。不同冷却方式下获得的铁素体晶粒平均尺寸差别不大。此外，在所有情况下，除了一些残留在原始珠光体群上的渗碳体片层外，大部分渗碳体片层都转变为渗碳体颗粒。还发现铁素体亚结构和渗碳体颗粒的析出受冷却方式的显着影响。与其他冷却方式相比，炉冷有利于显微组织的均匀性。炉冷后，颗粒更均匀地分布在铁素体基体上，从而使强度和延展性更好地结合在一起。