Structure of steel 0Kh12G14N4Yu2 after deformation under conditions of superplasticity

Conclusions

• 1. Plastic deformation greatly refines ferrite and austenite grains in steel 0Kh12G14NYu2 and changes the shape of austenite grains from lamellar to equiazed. The density of intragranular dislocations is low in both phases after thermoplastic treatment.

• 2. Deformation under conditions of superplasticity induces enlargement of the structural components of the steel; austenite grains form conglomerates of complex shape that consist of fragments larger than the original austenite grains but practically no different in shape; the shape of ferrite grains, on the contrary, changes greatly.

• 3. The dislocation density in ferrite grains decreases as the result of plastic flow and no dislocations at all are observed in some δ ferrite grains; the dislocation network in austenite grains is disrupted and dislocation rows restrained at the interphase boundaries are observed.

• 4. The results obtained point to the influence of both displacement and diffusional mechanisms of superplastic flow under the given conditions.