Effect Of Forging Process Parameters On Fatigue Life Of Ti-6Al-4V Alloy

Due to its excellent comprehensive properties,Ti-6A1-4V alloy is widely used in aerospace,marine ships and large-scale nuclear power fields as an important structural material for its core components.Most of these parts are formed by forging.The severe service environment and high standard service requirements make the fatigue life of Ti-6A1-4V alloy more and more important.Due to the low thermal conductivity,strain rate sensitivity and narrow forging temperature range of Ti-6A1-4V alloy,the forging process of Ti-6A1-4V alloy is very difficult,which will easily lead to the instability of forging quality and threaten the safety and reliability of service parts.Therefore,it is very important to study the influence of different forging parameters on fatigue behavior of Ti-6A1-4V alloy,and then establish the complex mapping relationship between forging process parameters and fatigue life.In this paper,the relationship between the process parameters and the fatigue life of the forging samples of Ti-6A1-4V alloy under the different forging process is revealed by physical experiments,simulation and regression analysis.The main research contents are as follows:(1)According to the investigation of engineering practice,the key forging process parameters are determined,and the reasonable forging experiment scheme and relevant mechanical property test scheme are formulated.Based on the physical experiment data,the fatigue life simulation model of Ti-6A1-4V alloy forging sample is established and modified by ABAQUS and Fe-safe software.(2)The existing fatigue life prediction theory and mathematical model were analyzed and verified.Combined with the fatigue experimental data under the background of relevant engineering application in the research content(1),the appropriate life prediction method is selected and further modified,which is the basis for the subsequent establishment of the relationship model for forging process parameters on fatigue life,and the required characteristic parameters in the life prediction method are defined.(3)Based on the room temperature tensile test data of forgings,the influence of forging technology on the above characteristic parameters is analyzed.The mapping relationship between forging process parameters and characteristic parameters is determined by multivariate nonlinear regression.Combined with the life prediction method selected before,the fatigue life prediction model based on forging process parameters is established,and from this,it is determined that the fatigue life requirements of Ti-6Al-4V alloy forgings can be achieved by the corresponding optimal forging process parameter group.The fatigue life prediction model based on forging process parameters established in this paper plays a positive role in guiding the optimization of forging process and improving the fatigue performance of forgings.And it has an important guiding significance for further improving the forging plastic forming technology.