PDF(Pubmed)
Abstract：
The plastic deformation of TWIP steel is greatly inhibited during the expansion process. The stress-strain curves obtained through expansion experiments and observations of fracture morphology confirmed the low plastic behavior of TWIP steel during expansion deformation. Through an analysis of the mechanical expansion model, it was found that the expansion process has a lower stress coefficient and a faster strain rate than stretching, which inhibits the plasticity of TWIP steel during expansion deformation. Using metallographic microscopy, transmission electron microscopy, and EBSD to observe the twin morphology during expansion deformation and tensile deformation, it was found that expansion deformation has a higher twin density, which is manifested in a denser twin arrangement and a large number of twin deliveries in the microscopic morphology. During the expansion deformation process, dislocation slips are hindered by twins, the free path of the slips is reduced, and dislocations accumulate significantly. The accumulation area is the initial point of crack expansion. The results show that the significant dislocation accumulation caused by the delivery of a large number of twins under expansion deformation is the main reason for the decrease in the plasticity of TWIP steel.
摘要：
TWIP钢的塑性变形在膨胀过程中受到很大的抑制。通过膨胀实验和断口形貌观察获得的应力-应变曲线证实了TWIP钢在膨胀变形过程中的低塑性行为。通过对力学扩展模型的分析,发现膨胀过程比拉伸具有更低的应力系数和更快的应变速率，这抑制了TWIP钢在膨胀变形过程中的塑性。使用金相显微镜，透射电子显微镜,和EBSD观察膨胀变形和拉伸变形过程中的孪晶形态，发现膨胀变形具有较高的孪晶密度，在微观形态上表现为更密集的孪生排列和大量的孪生传递。在膨胀变形过程中，位错滑移被双胞胎阻碍，单据的自由路径减少了，位错明显积累。堆积面积是裂纹扩展的初始点。结果表明，膨胀变形下大量孪晶的传递引起的显著位错堆积是TWIP钢塑性下降的主要原因。
