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本文研究了Ti-7Al-4Mo合金在扭转变形时剪切带的产生和扩展。实验观察表明:α-β型Ti-7Al-4Mo合金棒材在单次过载扭转实验时,试样的开裂和最终的断裂方式随热加工条件不同而显著不同。在β相区加工的试样是沿晶界α相与转变了β的交界处先形成剪切带,然后沿剪切带开裂;在两相区偏低的温度加工的试样是沿初生α与转变了β的交界处形成剪切带并在此开裂。轧制试样终轧温度低,试样有各向异性,容易发生纵向集中滑移(即剪切带);挤压试样终挤温度高,各向异性小,剪切带沿纵向、横向均匀分布。纵向集中滑移带剪切开裂、扩展、导致最终劈断;横向集中滑移带剪切开裂、扩展,导致最终平断。文中用位错连续分布和断裂力学原理分析了剪切开裂的现象,并讨论了剪切带的长大。
In this paper, the generation and propagation of shear band in Ti-7Al-4Mo alloy during torsional deformation were studied. The experimental observations show that the cracking and the final fracture mode of the α-β Ti-7Al-4Mo alloy bar during the single overload torsion test are significantly different with the thermal processing conditions. The samples processed in the β-phase region are formed along the shear band along the α-phase and the β-transformed interface, and then crack along the shear band. Samples processed at a low temperature in the two-phase region are formed along the primary α And the transformation of the junction of β shear zone and the formation of cracking in this. The final rolling temperature of the rolled sample is low, the sample is anisotropic, prone to longitudinal slip (ie, shear band); high extrusion end temperature extrusion, anisotropy, shear zone along the vertical and horizontal Evenly distributed. Longitudinal centralized slip band shear cracking, expansion, resulting in the final split; horizontal centralized slip band shear cracking, expansion, resulting in the final Pingbian. In this paper, the phenomenon of shear cracking is analyzed by the theory of dislocation continuity and fracture mechanics, and the growth of shear band is discussed.