Surface Strengthening of Ti-6A1-4V Alloy by Glow Plasma Carbonization Process

A glow plasma carburizing technique was applied to strengthen the surface of the Ti-6A1-4V alloy. The alloy was carburized at 950 degrees C and 30 similar to 35 Pa for 3 h using plasma of Ar gas. Graphite rod was employed as carbon supply to avoid the hydrogen brittleness which is common in traditional gas carbonization. The carburized layer was examined by an optical microscope (OM), field emission scanning electron microscope (FESEM), and X-ray diffractometer (XRD). The wear resistance under ring-block wear testing and the surface hardness were evaluated and compared to those for the untreated material. Results show that a carburized layer (416 mu m thick), mainly composed of TiC and V8C7, is found. These hard carbides contributed to the imrovement of the hardness and wear resistance.