The strain-hardening parameter h, measured during creep by means of small stress increments, is usually found to have values of 0.1–2G, where G is the shear modulus. Depending on material, the value can be stress-independent or can vary as the reciprocal of the stress. A model is proposed which can account for both the magnitude of h and its observed stress dependence. In the model it is assumed that dislocations, activated by a stress increment within subboundaries, can traverse the subcell diameter, d. The observed behaviour of h is dependent on the relationship between d and stress, and on the friction stress, σo, of the material.
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