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Modelling of plastic deformation via segmented voce curves, linked to characteristic LEDS's which are generated by LEDS transformations between workhardening stages

1995; Wiley; Volume: 149; Issue: 1 Linguagem: Inglês

10.1002/pssa.2211490110

1521-396X

D. Kuhlmann‐Wilsdorf,

Metal Alloys Wear and Properties

The LEDS theory is briefly surveyed and is shown to predict 1, that the partitioning of stress-strain curves into the commonly recognized workhardening stages is caused by LEDS transformations which lower the energy per unit length of discolation line in accordance with the LEDS hypothesis; 2. that, to a first approximation, the rate of glide dislocation trapping decreases linearly with the applied stress; 3. that such trapping is the dominant cause of workhardening and that therefore the workhardening coefficient tends to decrease linearly with the flow stress; 4. that this behavior gives rise to tensile true stress-true strain curves which are sequences of Voce curves, correlated with specific LEDS types; 5. that therefore the Voce parameters can be connected with measurable parameters of the dislocation microstructure; 6. that superimposed on the Voce curves are gradual changes of the "frictional" stress, τ, composed of Hall-Petch, solid solution and particle hardening; 7. that the Hall-Petch relationship has a simple general basis independent of the specific prevailing LEDS structure; 8. that other components of τ, specifically due to solid solution and precipitation hardening, should not catch the bulk of attention as in the past, since in fact the corresponding physical effects can greatly influence the Voce parameters and thus dwarf the respective contributions to τ; 9. that simple regularities exist regarding the Voce parameters which can be studied via a combination of TEM investigations plus slip line determinations, X-ray studies and calorimetry as may be suitable; 10. that by means of such directed studies the construction of equations of state within wide ranges of strain, strain rates and temperature, will become possible.