Effect of N addition on the microstructure and work-hardening behavior of a high Ti and W-alloyed cast steel

The present study proposes and analyzes the effect of N additions to promote the formation of (TiW)CxN1-x carbides to improve hardness and reduce the volume fraction of intergranular M₆C carbides. Metallographic characterization showed that N addition reduces the carbide size but increases the carbide count, producing a better distribution, which is attributed to the increase in the nucleation sites due to the presence of N during the primary carbide precipitation. A general increase in hardness is observed with a 0.13wt % N addition by the solid solution of N in the austenitic matrix and, at the same time, increases the work-hardening capability. The increase in the as-cast hardness and work-hardening behavior, coupled with the favorable modification of the finer and well-distributed reinforcing carbides, make this steel an excellent candidate for applications where high toughness and wear resistance in the as-cast condition are required, suppressing the need for heat treatment.