Effect of the Rate and Temperature of Hot Deformation on Strain Resistance of Duplex Stainless Steel

The effect of the temperature and rate of hot deformation on the structure and strain resistance of duplex stainless steel DSS 2205 is considered. Tests for hot compression of specimens are conducted at a temperature of 1223 – 1473 K and deformation rate 0.01 – 30 sec –1 to a degree of 0.4 and 0.8. Maps of deformation mechanisms are plotted. It is shown that the strain resistance decreases after attaining a maximum value in the flow curve, and the flow stress increases with decrease of the temperature and increase of the rate of the deformation. The activation energy of the hot deformation is shown to vary in accordance with the partitioning of strain between the two phases (ferrite and austenite) in the structure of the steel. The rate and the temperature of the deformation affect the deformability of the duplex steel considerably. Continuous dynamic recrystallization of ferrite is activated strongly in the range of flow stability. The range of flow instability is characterized by weak continuous dynamic recrystallization in the ferrite and discontinuous dynamic recrystallization in the austenite.