Effect of initial grain size (I.G.S.) on static recrystallization softeningin Cr steel (0.77 wt. percent Cr) has been investigated through the use of interrupted hotcompression tests and stress relaxation curves from ...Effect of initial grain size (I.G.S.) on static recrystallization softeningin Cr steel (0.77 wt. percent Cr) has been investigated through the use of interrupted hotcompression tests and stress relaxation curves from Gleeble 1500. Initial grain sizes were variedbetween 20 and 93 microns. Stress strains curves for Cr steel for different initial grain sizes andrecrystallization times have been highlighted. Similar observation was made for metadynamicrecrystallization with shorter retardation times. Statically recrystallized grain size alsoincreased as initial grain size increases. It is found that the values of initial grain size havesignificant effects on the mean flow stress and static recrystallization kinetics as well as thepeak strain values to initiate dynamic recrystallization.展开更多
The influences of initial grain size(IGS)with 20μm and 50μm on the hot flow behavior and microstructural changes of pure copper were investigated using hot compression tests at a temperature range of 623–1073 K and...The influences of initial grain size(IGS)with 20μm and 50μm on the hot flow behavior and microstructural changes of pure copper were investigated using hot compression tests at a temperature range of 623–1073 K and strain rate range of 0.001–0.1 s^(-1).The effects of critical stress and corresponding critical strain were studied based on the internal and external processing parameters.The critical stress and strain decreased with increasing temperature and decreasing strain rate.The investigation results of the microstructure and true strain–stress diagrams showed that dynamic recovery,dynamic recrystallization(DRX),and twinning mechanisms were caused during the hot deformation of pure copper.Microstructure evolution indicated some DRXed fine-grain took place around grain boundary of hot deformed samples with IGS of 20μm whereas DRXed fine-grain took place in interior grains for samples with larger IGS.The results also showed that grain growth is also dependent on IGS as the grain growth rate for samples with the larger IGS is greater than the smaller IGS.The critical strain rate and the temperature were obtained at 0.01 s^(-1) and 973 K,respectively,for the sudden change in the grain growth rate.Also,twinning highly depended on IGS which almost did not happen in fine grain size while the volume fraction of twinning increased with increasing grain size.展开更多
文摘Effect of initial grain size (I.G.S.) on static recrystallization softeningin Cr steel (0.77 wt. percent Cr) has been investigated through the use of interrupted hotcompression tests and stress relaxation curves from Gleeble 1500. Initial grain sizes were variedbetween 20 and 93 microns. Stress strains curves for Cr steel for different initial grain sizes andrecrystallization times have been highlighted. Similar observation was made for metadynamicrecrystallization with shorter retardation times. Statically recrystallized grain size alsoincreased as initial grain size increases. It is found that the values of initial grain size havesignificant effects on the mean flow stress and static recrystallization kinetics as well as thepeak strain values to initiate dynamic recrystallization.
文摘The influences of initial grain size(IGS)with 20μm and 50μm on the hot flow behavior and microstructural changes of pure copper were investigated using hot compression tests at a temperature range of 623–1073 K and strain rate range of 0.001–0.1 s^(-1).The effects of critical stress and corresponding critical strain were studied based on the internal and external processing parameters.The critical stress and strain decreased with increasing temperature and decreasing strain rate.The investigation results of the microstructure and true strain–stress diagrams showed that dynamic recovery,dynamic recrystallization(DRX),and twinning mechanisms were caused during the hot deformation of pure copper.Microstructure evolution indicated some DRXed fine-grain took place around grain boundary of hot deformed samples with IGS of 20μm whereas DRXed fine-grain took place in interior grains for samples with larger IGS.The results also showed that grain growth is also dependent on IGS as the grain growth rate for samples with the larger IGS is greater than the smaller IGS.The critical strain rate and the temperature were obtained at 0.01 s^(-1) and 973 K,respectively,for the sudden change in the grain growth rate.Also,twinning highly depended on IGS which almost did not happen in fine grain size while the volume fraction of twinning increased with increasing grain size.
