Precipitation of vanadium carbides in 0.8% C-13% Mn-1% V austenitic steel

Abstract

The precipitation mechanism of vanadium carbides in 0.8% C-13% Mn-1% V austenitic steel was investigated by transmission electron microscopy and energy dispersive X-ray spectroscopy techniques. The precipitate size and nucleation sites were observed to differ with different heat-treatment cycles applied. Carbide particles were mainly seen to precipitate on grain boundaries, in the matrix and in association with stacking faults, depending on the ageing conditions. Characteristic stacking fault contrast was observed after ageing at low temperatures and stacking fault precipitation occurred in the samples that were water quenched and aged at high temperatures; whereas samples which were not water quenched showed only local matrix precipitation. Energy dispersive X-ray spectroscopy showed that the carbide particles are rich in vanadium. The observations suggest that the nucleation of these particles on stacking faults depends on the point defect concentration and dislocation density in the matrix, prior to ageing.