Solute Cr atom distribution and fracture behaviour of MANET steel

The effects of heat treatments at 700°C on the toughness behaviour have been investigated in MANET steel by means of Charpy impact tests and SEM observations with microanalysis. The ductile to brittle transition temperature, the upper shelf energy and the slope in the ductile to brittle transition depend strongly on the time of heating as a consequence of the different fracture mechanisms evolving with the thermal treatment. The transition, from fracture mainly conditioned by lath boundaries to fracture depending mainly on processes at the PAG boundaries, appears correlated with the specific characteristics of the distribution of the Cr atoms in solution.