Surface mechano-chemical case carburising treatment (SMCT) of Ni-Cr-Mo steel: a post-annealing and differential scanning calorimetric (DSC) analysis

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.

KEYWORDS:

• Low temperature annealing
• surface mechano-chemical carburising treatment (SMCT)
• DSC
• nano grains
• thermal stability
• recovery
• re-crystallisation
• grain growth

Acknowledgments

Authors are thankful to Director MANIT, Bhopal for SMCT and different characterization process to carry out the research work and complete this study.

Disclosure statement

No potential conflict of interest was reported by the authors.