Effect of high temperature thermal exposure on high cycle fatigue performance of Ti60 titanium alloy
Effect of high temperature thermal exposure on high cycle fatigue performance of Ti60 titanium alloy during room temperature rotational bending was studied.By analyzing the surface characteristics and internal structure of the samples,the reasons for the changes in fatigue performance were explained.The results show that after thermal exposure at 600 ℃ for 100 h,the room temperature strength of the alloy increases while the plasticity decreases,and the high cycle fatigue strength during the room temperature rotating bending increases from 470 MPa to 543.3 MPa.The changes in fatigue performance are caused by both surface characteristics and internal structural changes.Thermal exposure leads to the formation of an oxide film composed of TiO2 and Al2O3 on the surface of the specimen,resulting in an increase in surface roughness and a decrease in surface quality,which has an adverse effect on the fatigue performance.At the same time,thermal exposure causes an increase in the precipitation amount and size of α2 phase and silicides in the alloy,and the change in precipitates leads to an increase in the strength of the alloy and further enhances its fatigue strength.Taking into account both factors,the improvement of rotational bending high cycle fatigue strength caused by precipitated phases is larger than the adverse effects caused by surface roughness increase,which is the main factor for the improvement of fatigue performance.
NETL
NSTL
万方数据
