Abstract
Double compression tests were performed on a Gleeble-3800 thermomechanical simulator to study the softening behaviors of deformed austenite in a V-N microalloyed steel. The static recrystallization volume fractions were calculated by stress offset method, and the kinetic model of static recrystallization was constructed. The effects of temperature, strain, and time interval on the softening behaviors were analyzed, and the interactions between precipitation and recrystallization were discussed. The results show that the softening behaviors of the deformed austenite at lower temperature or higher temperature are markedly different. At the temperature of 850°C or 800°C, pinning effects of the precipitates play the main role, and the recrystallization process is inhibited, which leads to the formation of plateaus in the softening curves. An increase in strain promotes the precipitation and recrystallization processes while reduces the inhibition effect of precipitation on recrystallization as well.
Highlights
Thermomechanical controlled processing is a well-known way to provide a good combination of strength, fracture toughness, and weldability in microalloyed steels [1]
Vanadium is known to be the microalloying element that can delay static recrystallization kinetics significantly by the formation of carbides, nitrides, and/or carbonitrides [2,3,4], which can be seen in the values of t0.5, activation energy, and static recrystallization critical temperature for higher vanadium additions [5]
It has been proved that vanadium can exhibit its potential by the applications of microalloying technology, and the steel products with high strength can be produced by lower vanadium and higher nitrogen additions
Summary
Thermomechanical controlled processing is a well-known way to provide a good combination of strength, fracture toughness, and weldability in microalloyed steels [1]. It has been proved that vanadium can exhibit its potential by the applications of microalloying technology, and the steel products with high strength can be produced by lower vanadium and higher nitrogen additions [8], which leads to a lower cost for steel industry. Few works on the steels with lower vanadium and higher nitrogen additions are reported It has been proved in Yang and Zhang’s [8, 9] and Bangming et al.’s [10] works that nitrogen is a very cost-effective microalloying element, which provides a new approach to produce high strength steels with low cost and high additional value. The softening behaviors of a microalloyed steel with low vanadium (0.05 mass%) and high nitrogen (0.018 mass%) additions were studied by performing double compression tests on a Gleeble-3800 thermomechanical simulator. The effects of the process parameters on recrystallized volume fraction, the precipitation and the interaction between precipitation, and recrystallization were analyzed to provide a reference for the prediction of the microstructural evolution and properties in the hot rolling process
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