1Cr18Ni9Ti管材拉伸断裂过程中裂纹扩展的研究

在管材弯曲成形系列研究的基础上,尝试采用单向拉伸试验获取了1Cr18Ni9Ti 管形状态下材料的真实力学性能参数,推导出仅测试管外径即可计算得出均匀变形任意时刻真实拉伸应力的近似公式,得出裂纹扩展规律并结合有限元分析了颈缩过程中的应力应变分布。结果表明:颈缩过程中,内、外侧壁应力状态存在一定差异,裂纹最先产生在内侧壁附近,并最后扩展至外侧壁;同时,最大轴向应力因外侧壁发生一定卸载而产生在靠近内侧壁某一区域,最大轴向应变产生在最后破裂的外侧壁处。

Research on Crack Propagation in the Crack Process of 1Cr18Ni9Ti Tube Under Uniaxial Tension

Based on a series of explorations on tube bending, the true mechanical property parameters of 1Cr18Ni9Ti tube are obtained through uniaxial tensile test. An approximate equation of true tensile stress at any moment in the uniform deformation process is derived and the corresponding result could be obtained by merely measuring the outer diameter of tube. Crack propagation law and stress-strain distribution in the necking process are discussed by experiment and simulation. The result shows that there exists a discrepancy in the stress states in the inner and outer tube walls during necking. Crack occurs first in the area which is close to the inner tube wall and subsequently propagates to the outer tube wall. In the meanwhile, the maximum axial stress energes in an area close to the inner tube wall due to unloading in the outer tube wall and the maximum axial strain yields in the outer tube wall where the crack occurs last.