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Title: Residual Stress-induced Subsurface Fatigue Crack Nucleation In Shot Peened Titanium Alloys
Author: Maawad, Yi, Brokmeier, Wollmann, Wagner
Source: Conf Proc: ICSP-10 Tokyo, Japan 2008
Publication year 2008
Document number: 2008117
Number of pages: 6
Abstract:
ABSTRACT
High-cycle fatigue performance of shot peened titanium alloys is associated with subsurface fatigue crack nucleation. This phenomenon may be related to the presence of
process-induced residual tensile stresses necessarily present below the mechanically treated surface and required to balance the outer compressive stress field. Although an
analysis of these deeply located residual tensile stresses is quite difficult, there is evidence to what extent the HCF strength of the various titanium alloy classes can be
affected by residual tensile stresses. Most important are tensile mean stress and environmental sensitivities of the materials HCF strengths. Anomalous mean stress
sensitivities as observed in (á+â) titanium alloys as well as low environmental sensitivities as found in metastable â-alloys can result in drastic losses in HCF performance
relative to residual stress-free electropolished references. On the other hand, both normal mean stress sensitivity as well as high environmental sensitivity as typically
observed in á-titanium alloys can lead to marked enhancements in HCF performance. Applied stress gradients as present in bending tend to improve the HCF performance by
reducing the critical stress level at the subsurface fatigue crack nucleation sites.
KEY WORDS Subsurface fatigue cracks, residual tensile stresses, mean stress sensitivity, environmental sensitivity
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This page last revised: 03/22/2010