Effect of microstructure on fretting fatigue and sliding wear of highly workable titanium alloy, Ti–4.5Al–3V–2Mo–2Fe

The effects of frictional wear characteristics and microstructural factors such as volume fraction and diameter of primary α phase on fretting fatigue strength of Ti–4.5Al–3V–2Mo–2Fe annealed at various temperatures were investigated in this study. The fretting fatigue life of Ti–4.5Al–3V–2Mo–2Fe is hardly affected by the volume fraction and diameter of the primary α phase in the low cycle fretting fatigue life region. The fretting fatigue limit of Ti–4.5Al–3V–2Mo–2Fe tends to increase with decrease in the volume fraction and average diameter of primary α phase. However, when volume fraction and average diameter of primary α phase are below certain values, the fretting fatigue limit is lowered by coarsening of the acicular α phase, which precipitates in the β phase region. The weight of wear debris that is swept out from the specimen surface in frictional wear test of Ti–4.5Al–3V–2Mo–2Fe tends to increase with decrease in hardness. The fretting fatigue life of Ti–4.5Al–3V–2Mo–2Fe tends to decrease with increase in the weight of wear debris that is swept out from the specimen surface in fretting fatigue test and increase in the depth of the crack growth zone caused by contact pressure.