The static recrystallization behavior of low-alloy steel Q345B during double-pass hot compression deformation tests was investigated in the temperature range of 900-1000 ℃,the true strain range of 0.15-0.25 and the i...The static recrystallization behavior of low-alloy steel Q345B during double-pass hot compression deformation tests was investigated in the temperature range of 900-1000 ℃,the true strain range of 0.15-0.25 and the interpass time range of 0.5-50 s on Gleeble-3500 thermo-simulation machine.The results show that static recrystallization during the interpass time is observed.As the deformation temperature and strain increase,softening caused by static recrystallization is obvious.According to the analysis and calculation of thermo-simulation data,the static recrystallization activation energy was obtained and static recrystallization kinetics model was built.Finally,the error analysis of static recrystallization kinetics model proved that the model had good accuracy.Therefore,this model provides a theoretical basis for static recrystallization（SRX）and will contribute to the development of multipass hot rolling process,in order to control the rolling process more accurately.展开更多
Studying the thermo-mechanical behavior of ductile iron is necessary to develop the rolling process for ductile iron sheet/strip production, thus, extending its application by replacing steel in several fields such as...Studying the thermo-mechanical behavior of ductile iron is necessary to develop the rolling process for ductile iron sheet/strip production, thus, extending its application by replacing steel in several fields such as machine casing, constructional applications, etc. In order to predict the safe rolling conditions for producing sheets and strips, the thermo-mechanical behavior of a ductile iron alloy, with CE of 4.48, is studied by physical simulation of hot rolling process using Gleeble-3500 simulator. The test was conducted on specimens at a range of deformation temperatures from 800°C to 950°C while three different strain rates;namely 0.05, 0.1 and 0.5 s-1 were used. The results obtained, show minimum values of flow stresses at 850°C. By increasing the deformation temperature up to 900°C, the flow stresses increased to reach maximum values, beyond which the flow stress decreased again. A remarkable dynamic recrystallization is observed at the deformation temperatures of 850°C and 800°C with applied strain rates of 0.05 and 0.1 s-1. Gleeble test results are correlated with microstructure observations on samples quenched at their deformation temperatures, where the changes in structure and graphite morphology are reported. The deformation process at high temperatures namely 950°C and 900°C result in changing the graphite shape from a spheroidal-like to a saucer-like shape. However, by decreasing the deformation temperature to 850°C as well as 800°C, graphite with lamellar shape is observed. As a conclusion, ductile iron could be successfully deformed without cracking at the applied conditions.展开更多
基金Item Sponsored by Fok Ying Tung Education Foundation(101048)Natural Science Foundation of Hebei Province of China(E2008000835)
文摘The static recrystallization behavior of low-alloy steel Q345B during double-pass hot compression deformation tests was investigated in the temperature range of 900-1000 ℃,the true strain range of 0.15-0.25 and the interpass time range of 0.5-50 s on Gleeble-3500 thermo-simulation machine.The results show that static recrystallization during the interpass time is observed.As the deformation temperature and strain increase,softening caused by static recrystallization is obvious.According to the analysis and calculation of thermo-simulation data,the static recrystallization activation energy was obtained and static recrystallization kinetics model was built.Finally,the error analysis of static recrystallization kinetics model proved that the model had good accuracy.Therefore,this model provides a theoretical basis for static recrystallization（SRX）and will contribute to the development of multipass hot rolling process,in order to control the rolling process more accurately.
文摘Studying the thermo-mechanical behavior of ductile iron is necessary to develop the rolling process for ductile iron sheet/strip production, thus, extending its application by replacing steel in several fields such as machine casing, constructional applications, etc. In order to predict the safe rolling conditions for producing sheets and strips, the thermo-mechanical behavior of a ductile iron alloy, with CE of 4.48, is studied by physical simulation of hot rolling process using Gleeble-3500 simulator. The test was conducted on specimens at a range of deformation temperatures from 800°C to 950°C while three different strain rates;namely 0.05, 0.1 and 0.5 s-1 were used. The results obtained, show minimum values of flow stresses at 850°C. By increasing the deformation temperature up to 900°C, the flow stresses increased to reach maximum values, beyond which the flow stress decreased again. A remarkable dynamic recrystallization is observed at the deformation temperatures of 850°C and 800°C with applied strain rates of 0.05 and 0.1 s-1. Gleeble test results are correlated with microstructure observations on samples quenched at their deformation temperatures, where the changes in structure and graphite morphology are reported. The deformation process at high temperatures namely 950°C and 900°C result in changing the graphite shape from a spheroidal-like to a saucer-like shape. However, by decreasing the deformation temperature to 850°C as well as 800°C, graphite with lamellar shape is observed. As a conclusion, ductile iron could be successfully deformed without cracking at the applied conditions.
