Abstract: 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.

Key words: solid mechanics, tube tension, crack propagation, stress-strain