In Situ Observation of the Evolution of Intragranular Acicular Ferrite at Ce-Containing Inclusions in 16Mn Steel

摘要

The effects of chemical compositions and austenitizing temperature on the formation of intragranular acicular ferrite (IAF) of 16Mn steel were systematically investigated, and the in situ observation of the evolution of IAF at Ce-containing inclusions was carried out using a high-temperature laser scanning confocal microscopy. The results show that trace amount of Ce can induce the IAF nucleation, while the optimum content of Ce is around 0.02 wt%. The appropriate austenitizing temperature is around 1200°C and the optimal prior austenite grain size is about 120 μm. The temperature range for IAF transformation is around between 557 and 623°C, and the time for which is about 13 s. The disregistries between Ce-containing inclusions and α-Fe are so small that may act as highly effective nuclei of IAF.