Effect of Alloying Elements on the Transformation and Impact Property of Austenitic High Manganese Steels

Abstract

The 13% Mn steel are widely used for abrasion resisting materials. The effects of various alloying elements have ben examined with regard to increusing the mass and the operating life of the material. In the present investigation four types of commercial steels were chosen and the effects of C, Mn and Cr in 13% Mn, of Mo in 13% Mn-%Cr, of C, V and Ti in 12%Mn-2%Mo, and of Mn and Mo in 7%Mn-2%Cr on the isothermal transformation characteristics and thein influence on impact properties were examined. The results are summarized as follows:
1) The increase of C accelerates the formation of carbide and other transformation products, and in the excess of 1.2%C acicular carbide forms. Impact values are much reduced by this acicular carbide and pearlitic constituent, but less reduced by grain boundary carbide.
2) Decreasing Mn content below 10% promotes the formation of perlitic constituent, which causes the loss of impact values, but in the range of 10-15% Mn hardly affects the properties.
3) The addition of 2% Cr accelerates the precipitation of grain boundary carbide, but decelerates the precipitation of grain boundary carbide, but decelerates the formation of pearlitic constituent.
Thus Cr is effective in minimizing the loss of impact values due to grain boundary carbide.
4) Within 1%, Mo decelerates the formation of pearlitic constituent. Therefore Mo. when added together with Cr, is effective in improving the toughness of heavy section parts.
5) The addition of 0.1%V and 0.2%Ti slightly decelerates the formations of carbide and pearlitic constituent.