316LN不锈钢混晶组织微区不均匀塑性变形研究

Grain-level plasticity heterogeneities of the mixed-grain microstructure in 316LN stainless steel

针对核电主管道用钢316LN经常出现的混晶组织,通过实验与晶体塑性有限元分析了混晶组织的晶粒尺寸、取向等微观组织对微区塑性变形特点的影响规律。应用数字图像相关法(DIC)实验定量获得了6%变形条件下的微区变形分布,验证了晶体塑性有限元模型的正确性。通过大变形实验获得了晶粒变形结果和滑移带分布,并用晶体塑性有限元模拟再现了微区变形的不均匀性。研究发现,混晶组织的塑性变形是非常不均匀的,细晶组织具有明显的应力应变集中现象,并发生更明显的晶体转动,而粗晶的整体变形则相对较小,但局部区域亦表现出明显的应变集中和滑移带聚集。

For the mixed-grain microstructure of nuclear main pipeline steel 316LN,the influence of grain size and orientation of mixed-grain microstructure on the characteristics of grain-level plastic deformation was analyzed by experiments and crystal plasticity finite element simulation.Grain-level deformation distribution under 6%compression was quantitatively obtained by digital image correlation(DIC)experiment,by which the crystal plasticity finite element(CPFE)model was verified.Then the large deformation experiments were carried out to observe grain deformation and slip band distribution,and the CPFE simulations were implemented to investigate the inhomogeneity of grain-level deformation.It is found that the plastic deformation of the mixed-grain microstructure is highly heterogeneous.Fine grains generally show obvious stress and strain concentration,larger lattice rotations as well.While coarse grains show smaller overall deformation,but there is also obvious stain concentration and aggregation of slip bands in the local zone.