HCF Performance of the Shot Peened Ti-6246- Effects of Test Temperature

Author:  S. Yang, L. Wagner and M. Wollmann
Source:  Conf Proc 2014: ICSP-12 Goslar, Germany (pgs.96-101)
Doc ID:  2014057
Year of Publication:  2014
Abstract:  
The paper presents results on duplex microstructure of Ti-6246 which is used in compressor parts of aircraft engines. Shot peening (SP) was applied on axial fatigue specimens. Electrolytically polished specimens were prepared as reference. Surface properties of peened and reference conditions, such as surface roughness, cold work and residual stress (RS) were characterized using profilometer, microhardness tester and hole drilling method. High cycle fatigue behaviour of the peened specimens was examined under axial load at both room temperature (RT) and 450°C in contrast to the reference. It was found that shot peening could bring out a moderate enhancement in high cycle fatigue (HCF) strength at RT. With the increase in test temperature to 450 °C, fatigue limit in peened condition was maintained at the reference level, whereas lifetimes deteriorated at high stress amplitude regime. This is explained by the more marked effect of the increased surface roughness on acceleration of crack nucleation at elevated temperature where more than 40% RS relaxation occurred during the tests.