Gu Ji, Zhang Lixin, Ni Song, Song Min
State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, PR China.
State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, PR China.
Micron. 2018 Feb;105:93-97. doi: 10.1016/j.micron.2017.12.003. Epub 2017 Dec 11.
In this paper, two grain sized 304 austenitic steel rods (coarse-grained steel with an average grain size of ∼20μm and ultra-coarse-grained steel with an average grain size of ∼1mm) were treated by pre-torsional deformation. Gradient microstructures with "dislocations→stacking faults→nanotwins" along the radial direction were formed in the ultra-coarse-grained specimen, and this type of gradient microstructures is beneficial to the mechanical properties. The results also showed that grain size affects the onset of twinning. Under the same strain the onset of twinning in the ultra-coarse-grained specimen was postponed compared to the coarse-grained specimen, and the postponed onset of twinning further affected the martensite transformation. This work showed that applying pre-torsional treatment on large grain sized structural materials is beneficial to the overall mechanical properties.
在本文中，对两根不同晶粒尺寸的304奥氏体钢棒材（平均晶粒尺寸约为20μm的粗晶粒钢和平均晶粒尺寸约为1mm的超粗晶粒钢）进行了预扭转变形处理。在超粗晶粒试样中沿径向形成了具有“位错→层错→纳米孪晶”的梯度微观结构，这种梯度微观结构有利于力学性能。结果还表明，晶粒尺寸会影响孪晶的起始。在相同应变下，与粗晶粒试样相比，超粗晶粒试样中孪晶的起始被推迟，而孪晶起始的推迟进一步影响了马氏体转变。这项工作表明，对大晶粒尺寸的结构材料进行预扭转处理有利于整体力学性能。
