Author/Authors :
Abbasi، .M نويسنده Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran , , Kermanpur، .A نويسنده Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran , , Najafizadeh، .A نويسنده Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran , , Saeedipour، .S نويسنده Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran , , Mazaheri، .Y نويسنده Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran ,
Abstract :
The formation of nano/ultrafine grained ferrite in low carbon steels containing different amounts of niobium
was investigated using thermomechanical treatment which consisted of annealing of 85% cold rolled martensite
with different parameters. The specimens were characterized by optical and scanning electron microscopy and
Vickers hardness test. A lamellar dislocation cell structure was formed during cold rolling. An increase in hardness
was found during annealing with the addition of the Nb element. The mean grain size of the specimens annealed at
550 ?C for 300 s was approximately similar (ranging from 79 to 87 nm) for both chemical compositions. Increasing
annealing temperature to 600 ?C or annealing time to 2.7 ks led to a severe grain growth in the steel without Nb,
but no considerable changes in Nb containing steel were observed.
