This work reported a comparison between the wear and fretting fatigue(FF) behaviors of a Cr-alloyed layer and a Cr-Ti solid-solution layer.The hardness and toughness of both layers were evaluated to support this comparison.The results showed that the Cr-alloyed layer had high surface hardness but poor toughness,while the Cr-Ti solid-solution layer had excellent toughness but low hardness.The FF properties of the modified Ti6A14 V alloy depended on the trade-off between two factors:wear resistance and fatigue resistance.Although the Cr-alloyed layer could effectively resist the wear in fretting areas,its poor toughness caused the fatigue resistance to drop sharply and hence led to a premature failure in FF test.Due to the relatively good fatigue resistance,the Cr-Ti solid-solution layer had slightly higher FF life than that of the Cr-alloyed layer;however,its low hardness resulted in severe wear in correspondence with the fretting area and thus a failure to improve the FF properties of Ti6A14 V alloy.When combined with shot peening post-treatment,the FF life of both layers increased by about three times compared to that of the Ti6A14 V alloy.A further study showed that the poor toughness or low hardness still exerted negative influence on combination-treated samples.
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