T250马氏体时效钢晶粒尺寸对时效析出的影响

 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。

Relationship Between Grain Size and Aging Behavior of Co-Free Maraging Steel

After the heat treatment of 840 ℃×1 h+480 ℃×4 h, mechanical tests show that the properties of Co free maraging (T250) steel are not closely related to grain size. However, XRD analysis and corresponding microstructure observations reveal that the aging process is influenced by grain size obviously. Compared with coarse grain maraging steel, much more platelike reversed austenite is formed at boundary and sub boundary, which has a great deal contribution to toughness, and furthermore, very finer dispersive precipitates with prominently strengthening effect are formed in the matrix for fine grain maraging steel. These phenomena probably are the reasons why the strength as well as toughness of maraging steel is not influenced markedly by the prior austenite grain size.