Phase transformation and microstructure evolution of pearlite heat-resistant steel during heating

The phase transformation and microstructure evolution of pearlite heat-resistant steel during heating were observed with an ultra-high temperature confocal scanning laser microscope. The alpha-ferrite completely disappeared earlier than Fe3C during the formation of gamma-austenite, which is inconsistent with the fact that the Fe3C should disappear completely earlier under equilibrium conditions. After the Fe3C + alpha ->gamma transformation, static recrystallisation of gamma-austenite occurred, accompanied by the dissolution of cementite. During the gamma ->delta transformation, the delta-cell first precipitated at the triple point of the gamma-austenite grain boundaries, and then the delta-cell platelet with one tip appeared in the gamma-austenite grain. The law of delta/gamma inter-phase boundaries was analysed based on inter-phase boundary types and element diffusion.