The structure and precipitates of 0.05C-0. 13Nb steel deformed by 50% at different temperature between 950~750 ℃ have been studied by Gleeble- 1500D thermal simulation machine
SEM and TEM. Results showed that with deforming temperature decreasing from 950 ℃ to750 ℃
the polygonal ferite content(volume percent)in 0.05C-0. 13Nb steel increased from 20% to 80% and grain size of polygonal ferrite decreased from 9 μm to4 μm; the deformed structure in steel consisted of polygonal ferite
grain bainite and 1~3 μm martensite/austenite island; and the amount of 1~10 nmprecipitates Nb (C
N) in steel increased with decreasing deformed temperature.