On the sources of work hardening in multiphase steels assisted by transformation-induced plasticity

The mechanisms effectively responsible for the enhancement of the work-hardening capabilities of multiphase steels assisted by transformation-induced plasticity are highlighted. Different microstructures, some containing a proportion of retained austenite with various mechanical stabilities, are studied. The dislocation density generated within ferrite by the mechanically induced martensitic transformation of retained austenite is shown to scale with the incremental work-hardening exponent. The acoustic emission generated during tensile straining was also measured. The acoustic emission was revealed to result mainly from dislocation motion, especially from the motion of the additional dislocation density generated in intercritical ferrite by the strain-induced martensitic transformation.