LAUSR

ABSTRACT The Ni-Cr-Mo steel samples carburised by surface mechano-chemical case carburising treatment (SMCT) were subjected to post low temperature annealing to relieve excessive residual stress and to induce carbide formation of untransformed carbon in the subtract. Samples were DSC analysed before and after 30 and 60 minutes of SMC treatment to investigate and understand the stability of the nano grains and phase changes. From DSC analysis, it is found that the onset of body-centred cubic iron (α-Fe) into face-centred cubic iron (γ-Fe) transformed at a temperature of 732°C. However, samples subjected to SMCT showed a different behaviour especially at a temperature range of 100–450°C. i.e. an exothermic reaction in this regime.