Fatigue performance of metastable β titanium alloys: Effects of microstructure and surface finish |
| |
Authors: | Kocan Marcin Wagner Lothar Rack H J |
| |
Affiliation: | (1) Institute of Materials Science and Engineering, Clausthal University of Technology, Agricolastrasse 6, 38678 Clausthal-Zellerfeld, Germany;(2) School of Materials Science and Engineering, Clemson University, 213 Olin Hall, 29634 Clemson, SC |
| |
Abstract: | This investigation examined the role of microstructure and surface finish on the high cycle fatigue (HCF) performance of TIMETAL
LCB (Ti-6.8Mo-4.5Fe-1.5Al). The as-received microstructure of LCB consisted of elongated β grains with a semicontinuous grain
boundary α layer. In contrast, a fine equiaxed β + spheroidized α LCB microstructure was achieved by hot swaging and solution
(recrystallization) anneal. The latter modification of the prior β grain structure, together with the size, morphology, and
distribution of the primary α phase, resulted in a significant enhancement in the tensile and HCF properties. Furthermore,
prestraining (PS), as would be expected during the fabrication of an automotive coil spring, and prior to aging for 30 min
at temperatures between 500 and 550 °C, led to additional increases in tensile strength. In contrast, the HCF performance
was always reduced when PS prior to aging was included in the overall processing procedure. Finally, shot-peening and roller-burnishing
both resulted in an increased fatigue life in the finite life regimen; however, significant reductions in the 107 cycle fatigue strengths were observed when these procedures were used. These observations have been explained by including
the effect of process-induced residual tensile stresses in the fatigue analysis, resulting in subsurface fatigue crack nucleation.
This paper was presented at the Beta Titanium Alloys of the 00’s Symposium sponsored by the Titanium Committee of TMS, held
during the 2005 TMS Annual Meeting & Exhibition, February 13–16, 2005 in San Francisco, CA. |
| |
Keywords: | fatigue crack nucleation residual stress roller-burnishing shot-peening |
本文献已被 SpringerLink 等数据库收录! |
|