Fracture Along Planar Slip Bands
MICHIGAN TECHNOLOGICAL UNIV HOUGHTON DEPT OF METALLURGICAL ENGINEERING
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The conditions for propagation of a crack along an inhomogeneous slip band is considered. Allowing slip to occur in the crack plane but restricting the shear displacement to the crack plane results in a relaxed elastic-plastic state of stress near the crack-tip. Calculations of the resulting crack-tip flow behavior indicate that once a crack with a co-planar shear band has formed, it becomes difficult to activate secondary slip with a shear displacement inclined to the crack plane and inhomogeneous slip prevails. The difficulty of activating non-coplanar secondary slip results in large hydrostatic and normal stress near the crack-tip. The combination of large shear strain due to the inhomogeneous shear band and large normal or hydrostatic stresses present near the crack-tip leads to easy crack propagation along such bands. Fracture along slip bands in Ni-, Al-, and Ti-base alloys is briefly discussed in terms of the model.
- Metallurgy and Metallography