The influence of thermomechanical processing on the smooth fatigue properties of Ti-15V-3Cr-3Al-3Sn

This study has examined the potential for enhancing the fatigue performance of Ti-15V-3Cr-3Al-3Sn sheet through variations in heat treatment and thermomechanical processing procedures. Processing variants included conventional solution treatment and aging, solution treatment with duplex- and triplex-ages, and cold and warm rolling followed by aging. Tensile and smooth fatigue performance of each processing route were evaluated and compared to 'standard' commercial practice. These processing avenues provided a wide range of microstructures with tensile strengths ranging from 1070 to 1610 MPa. Enhancements in fatigue performance were dependent on processing and stress level. At high stresses, i.e. within the low cycle regime, a 15% improvement in the maximum stress for a fixed 30 000 cycle lifetime was achieved. At lower stresses, i.e. within the high cycle fatigue 'limit' regime, a 50% improvement relative to the standard heat treatment was achieved. A good correlation of fatigue and tensile strengths was observed; generally, the smooth fatigue properties improved as the tensile strength increased. (C) 1998 Elsevier Science S.A. All rights reserved.