Ni-1C二元合金宏观不均匀塑性变形与断裂行为研究

Investigation on Macroscopic Inhomogeneous Plastic Deformation and Fracture Behavior of Ni-1C Binary Alloy

研究了Ni-1C二元合金宏观不均匀塑性变形与断裂行为。通过对拉伸应力-时间和位移-时间曲线测量,分析了Ni-1C合金波特文-勒夏特利埃(Portevin-Le-Chatelier,PLC)效应锯齿波形和应力跌幅分布特征,利用三维数字图像相关法研究PLC变形带的形核增殖、时空演化以及断裂过程中裂纹的形成和扩展。结果表明,在3mm/min拉伸速率下,Ni-1C合金PLC效应表现为A型锯齿波,应力跌幅呈现幂率分布;PLC变形带在试样的夹头或标距段形核,向试样一侧连续增殖传播;裂纹萌生于试样标距段,逐渐扩展,导致韧性断裂,同时裂纹的萌生及扩展与PLC变形带之间没有关联。

The macroscopic inhomogeneous plastic deformation and fracture behavior of Ni-1C binary alloy were investigated.The type of serrations of Portevin-Le-Chateller effect and distributions of the stress drop magnitude of the Ni-1C alloy were analyzed according to tensile stress-time and displacement-time curves.The nucleation,propagation,temporal and spatial evolution of PLC bands together with fracture process of Ni-1C alloy were investigated by using three-dimensional digital image correlation method.The results reveal that the PLC effect of Ni-1C alloy shows A type of serrations and the power-law function of the statistical distributions of the stress drop magintudes at a strain rate of 3 mm/min.PLC band forms at the grip or gauge positions and propagates continuously.The crack is initiated at the gauge length of the sample and expands gradually,leading to ductile fracture.There is no correlation between the initiation and propagation of the crack and the PLC bands.