Experimental studies on yield behavior of steel under rapid heating

The yield behavior of steels under different heating rates and pre-stress levels is studied experimentally. The yield temperatures are found to increase with the treating rates and decrease with the pre-stress values. Two remarkable changes in the microstructures of tested steels are the grain elongation along the loading direction owing to the plastic deformation, and the grain refineries owing to the recrystallization. The micrographic features prove the above remarks. An equation of plastic strain rates of metals can estimate the yield temperature of metals under various heating rates. An extended Johnson-Mehl equation of recrystallization is derived, which includes the influence of heating rates. (C) 2001 Elsevier Science Ltd. All rights reserved.