Influence of Mn on Solubility of C and Snoek Peak in Low Carbon Steels

Abstract

The influence of Mn on the solubility of C in ferrite equilibrium with cementite was investigated in low carbon steels containing Mn ranging from 0 to 1 mass % over a temperature range from 573 to 973 K. Internal friction method was employed together with chemical analysis of C by means of infrared absorption method after combustion.
It has been clarified that Mn hardly changes the solubility of C in ferrite in equilibrium with cementite (0.018 mass% at 973 K), whereas Mn reduces Snoek peak height despite the fact that the amount of C in solid solution is constant.
The proportionality constant K in the equation sol. C (ppm) = K × Q^-1 _max(10^-4) was experimentally determined as a function of Mn content. K increases with increasing Mn content, which is caused by the lattice strain introduced by Mn atom and/or the chemical interaction between Mn and C atoms.