Effect of Melting Temperature on the Wear Characteristics of Austenitic Manganese Steel

The practice in most manganese steel melting furnace is to raise the melting and pouring temperatures to 1500C and above so as to enhance fluidity of the molten metal and ease removal of slag. High temperature promotes micro and macro carbide segregation of alloy elements and formation of embritting transformation products. The presence of segregation at the grain boundaries, acts as barrier to dislocation movement. This could be responsible for uneven, inconsistent wear rate and pattern of the steel.

inconsistent wear rate and pattern. The segregation around grain boundaries acts as barrier and impedes the movement of dislocation around the grain boundaries where the Cr-C segregation is highly pronounced. The increased metallic inclusion through back charging with foundry returns depreciates the ratio of mobile dislocation to immobile dislocation to a value lower than unity. This ratio translates to higher densities of immobile dislocation and subsequently poor work hardening property of the AMS. Thus, the material is favoured to fail by cracking when the energy of the mobile dislocation becomes lower than the energy of the immobile dislocation. The pouring temperatures of 1400 - 1450C will promote uniform dispersion of carbide particles within the structure and thereby enhancing the wear property of the jaw crusher. However, the low pouring temperatures diminish the fluidity of the molten metal and results in casting defects, low yield put and high operational costs. This phenomenon of segregation, arising from high temperature pouring can be reduced by using neutral refractory to line the lip pouring ladles as against the current practice of using CO2 sand. This will conserve heat in the ladle and reduce the rate of temperature drop. In the alternative, the use of bottom-pour ladle should be considered.