抄録
0.6C-Si-Mn steel has been studied to determine theeffects of bainitic transformation temperature in the range between 593 and 673K on the microstructure and tensile properties of Si-Mn steel.Carbide-free upper bainite whose individual ferrite was separated by the “thin-film” type of austenite appeared independent of temperature, while the ferrite width increased with increasing temperature. The “blocky” type of austenite was found with an increase in temperature. The carbon content decreased with increasing temperature and the thermal stability of the austenite decreased at and above 643K. Bainitic transformation at and above 643K followed by tempering at 473K significantly increased the percent elongation of the steel, as compared to bainitic transformation at and below 623K followed by tempering at 493K. From the true stress-true strain analysis, X-ray measurement and fractography, the improved ductility at and above 643K can be attributed to the transformation induced plasticity (TRIP) effect of austenite.
