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Title

ELEVATED TEMPERATURE DEFORMATION BEHAVIORS AND MICROSTRUCTURE EVOLUTIONS OF SA508-4N STEEL

Authorship

Shang, Xuekun; Du, Xiaowei; Wang, Xitao

Shang, Xuekun

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Du, Xiaowei

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Wang, Xitao

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DOI

10.5151/9785-9785-32309

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Abstract

The deformation behaviors under both tensile and compressive forces and microstructure evolutions of cast SA508-4N steel were investigated at elevated temperatures. True stress-strain data were obtained from hot deformation experiments performed on a Gleeble-3500 thermal-simulator under different temperatures (750-1200 ºC) and strain rates (0.001-10 /s). The reduction of area decreases as a function of temperature from 750 ºC to 900 ºC and then increases. At 1200 ºC, the reduction of area reaches more than 99% with the strain rates of 0.5 /s and 1.0 /s. The dynamic recrystallization under compressive stress occurs at 800 ºC under low strain rate and a complete dynamic recrystallization can be observed when the temperature reaches above 1100 ºC. The value of the thermal deformation recrystallization activation energy is 407.34 kJ. A “two-stage” flow stress constitutive model concerned with dynamic recovery and dynamic recrystallization was established based on the true stress-strain data. This model shows good agreement with experiment results. Moreover, a dynamic recrystallization model was developed to predict dynamic recrystallization fraction and grain size using thermal processing parameters.

Keywords

SA508-4N, Recrystallization, flow stress, constitutive model, hot deformation