Dislocations
introduction
dislocations
strengthening of metals

Introduction 1

Diagram of yield caused by shear stresses By the end of this tutorial, you should have an understanding of:

  • the ideal strength of materials
  • what dislocations are
  • the role of dislocations in plastic deformation
  • strengthening methods such as solid solution strengthening, intrinsic lattice resistance, precipitation and dispersion strengthening, work hardening and grain size strengthening.

In materials such as metals, permanent (or plastic) deformation occurs at stresses much less than the ideal strength, through the movement of dislocations. The dislocations cause the material to deform by the process of SHEAR.

Yield occurs by shear stress because tensile and compressive stresses create shear stresses. The shear stress is at a maximum at 45 degrees to the axis of tension or compression.

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