Dislocation structures in 16MND5 pressure vessel steel generated in uniaxial tension at different temperatures from -196DC up to 25DC
Résumé
Bainitic pressure vessel 16MND5 steel was strained in uniaxial tension at different temperatures, from liquid nitrogen temperature up to room temperature, using specimens with a uniform gauge section. The TEM observations of the deformed material show that the dislocations are distributed homogeneously at low applied plastic strain and gradually condense into high density structures, with increasing deformation. Dislocation condensation takes place in the form cell walls or tilt boundaries at temperatures T et8805; 0DC, in the form of sub-lath size clusters at temperature T et8804; -90DC. Unlike in pure iron, screw dislocation motion in bainite is rough. Such motion is accompanied with the emission dislocation loop debris, whose accumulation can produce 3D, polarized dislocation structures.