在840℃1 h固溶退火+480℃4 h时效处理条件下,不同晶粒度的T250马氏体时效钢力学性能比较试验表明,材料的性能和晶粒尺寸关系并不表现出明显的依存关系。相应的XRD和显微结构比较研究显示,马氏体时效钢的时效行为和晶粒尺寸相关。晶粒细小的马氏体钢时效时形成更多体积分数的逆转奥氏体,以膜状分布在晶界和亚晶界起到软化作用而有利于材料塑韧性的提高;同时产生更为细小弥散的沉淀相起到更为明显的强化作用。这可能是材料的力学性能和晶粒尺寸关系不明显的组织结构原因。 The comparison of the mechanical properties of T250 martensitic steel with different grain sizes under the conditions of 840 ℃ 1 h solution annealing and 480 ℃ 4 h aging shows that the relationship between material properties and grain size does not show obvious dependence relationship. The corresponding comparative study of XRD and microstructure shows that the aging behavior of martensitic steel is related to the grain size. Fine grain martensitic steel forms the reverse austenite with more volume fraction when aging, and distributes in film shape at the grain boundary and subgrain boundaries to soften the material, which is beneficial to improve the plasticity and toughness of the material; Diffusive sediment phase play a more significant enhancement. This may be the mechanical properties of the material and the relationship between grain size is not obvious organizational structure.